The Taurus Spitzer Survey: New Candidate Taurus Members Selected Using Sensitive Mid-Infrared Photometry

The Taurus Spitzer Survey: New Candidate Taurus Members Selected Using Sensitive Mid-Infrared Photometry

Abstract

We report on the properties of pre-main-sequence objects in the Taurus molecular clouds as observed in 7 mid- and far-infrared bands with the Spitzer Space Telescope. There are 215 previously-identified members of the Taurus star-forming region in our 44 square degree map; these members exhibit a range of Spitzer colors that we take to define young stars still surrounded by circumstellar dust (noting that 20% of the bonafide Taurus members exhibit no detectable dust excesses). We looked for new objects in the survey field with similar Spitzer properties, aided by extensive optical, X-ray, and ultraviolet imaging, and found 148 candidate new members of Taurus. We have obtained follow-up spectroscopy for about half the candidate sample, thus far confirming 34 new members, 3 probable new members, and 10 possible new members, an increase of 15-20% in Taurus members. Of the objects for which we have spectroscopy, 7 are now confirmed extragalactic objects, and one is a background Be star. The remaining 93 candidate objects await additional analysis and/or data to be confirmed or rejected as Taurus members. Most of the new members are Class II M stars and are located along the same cloud filaments as the previously-identified Taurus members. Among non-members with Spitzer colors similar to young, dusty stars are evolved Be stars, planetary nebulae, carbon stars, galaxies, and AGN.

stars: formation – stars: circumstellar matter – stars: pre-main sequence – infrared: stars
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1 Introduction

A complete inventory of all the coeval stars in a young stellar association, cluster, or group (hereafter “association”) enables studies of the initial mass function (IMF), disk fraction, and stellar rotational properties, among other pursuits. Information from associations with a range of ages enables understanding of the overall formation and evolution of young stars, including the change with time of disk fraction and stellar rotation rate. However, identifying all of the member stars of a given young association can be quite difficult. (By “member,” we mean objects that are clearly young, close to the same age, and often still associated with their natal cloud.) Finding all such members requires that one employ multiple observational techniques. These methods include but are not limited to X-ray surveys (e.g., Alcalá et al. 1996, Wolk et al. 2006), H surveys (e.g., Ogura et al. 2002), variability surveys (e.g., Carpenter et al. 2001, Rebull 2001), ultraviolet (UV) surveys (e.g., Rebull et al. 2000), and infrared (IR) surveys (e.g., Jørgensen et al. 2006, Rebull et al. 2007). At each wavelength, we can use the fact that stellar youth implies more flux at a given radiometric band (X-rays, H, UV, IR), or more flux variability, than older stars of comparable mass, allowing separation of association members from field contaminants. When we combine the information from surveys in multiple wavelengths, we must remember that the influence of extinction due to circumstellar matter and/or the molecular cloud is vastly different at different wavelengths; extinction affects UV and optical wavelengths much more strongly than IR. For young associations, many, but not all, legitimate members are identifiable using just one or a few survey methods.

There are advantages and disadvantages to studying nearby young associations. Identification of young members in an association is made easier if the objects are located at smaller heliocentric distances and therefore brighter on the whole. This is especially the case for low-mass members with very low luminosities; a complete census of these stars and brown dwarfs can be made only for very nearby star-forming regions. On the other hand, nearby star-forming molecular clouds cover large areas of sky and therefore require large investments of observing time. At just 137 pc (with a depth of 20 pc; Torres et al. 2007, 2009), the Taurus star-forming region is one of the closest large cloud complexes with hundreds of low-mass stars, ongoing star formation, and objects ranging in age up to 5 Myr. Studies of Taurus objects have significantly influenced our basic understanding of the star-formation process for decades (e.g., Herbig & Rao 1972, Kenyon et al. 2008). However, the Taurus Molecular Cloud is close enough that it subtends more than 100 square degrees of sky; surveying all or even most of it is difficult within typical telescope time allocations.

Infrared surveys led to the discovery that some stars have infrared excesses, interpreted as circumstellar matter (e.g., Aumann et al. 1984, Beichman et al. 1986). Most if not all low-mass stars form with circumstellar accretion disks, resulting in IR excesses for as long as the dusty circumstellar material survives (e.g., Hernandez et al. 2007). By using IR to survey a star-forming region, the stars with IR excesses are relatively easily distinguished from stars without such excesses. The Spitzer Space Telescope (Werner et al. 2004) provides an excellent platform for surveying star-forming regions in the mid-IR and far-IR, enabling stars with IR excesses to be identified; the member stars which do not have IR excesses must be recovered using different techniques such as the ones listed above. Because Spitzer relatively efficiently maps large regions of sky, it is a particularly useful tool for surveying large star forming regions.

We have conducted a large multi-wavelength imaging and spectroscopic survey of the Taurus Molecular Cloud (TMC) in order to test if our inventory of Taurus members with infrared excesses is, in fact, complete. The Spitzer imaging component is referred to as the Taurus Spitzer Survey, and is described by Padgett et al. (2008; hereafter P08) and Padgett et al. (2009; hereafter P09). It covers 44 square degrees from 3.6 to 160 m and is a Spitzer Legacy Project, so enhanced data products have been delivered back to the Spitzer Science Center (SSC), including the catalogs on which this present paper is based. In addition to the Spitzer component, there are four other major components to our Taurus survey. XMM-Newton was used by the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST) program (e.g., Güdel et al. 2007 and references therein), which mapped 5 square degrees, most of which was also mapped by the Spitzer observations; the XEST data include X-ray imaging but also include ultraviolet data from the XMM-Newton Optical Monitor (Audard et al. 2007). XEST was deliberately pointed towards aggregates of previously identified Taurus members. In the optical, the Canada-France-Hawaii Telescope (CFHT) survey (Monin et al. in preparation; Güdel, Padgett, & Dougados 2007) mapped 28 square degrees (all of which are encompassed by the Spitzer area), and the Sloan Digital Sky Survey (SDSS) (Finkbeiner et al. 2004; Padmanabhan et al. 2008) mapped 48 square degrees in two perpendicular strips, about half of which overlaps the Spitzer area. Finally, the Five College Radio Astronomy Observatory (FCRAO) millimeter wavelength survey (Goldsmith et al. 2008) mapped 100 square degrees in the CO(1-0) line, covering the Spitzer survey area entirely. The relative coverages of these surveys is shown in P09. Our extended collaboration has already begun to use this rich dataset to search for new members of Taurus; Scelsi et al. (2007,2008) identified new candidate members using the XEST data, and Guieu et al. (2006, 2007) identified new brown dwarf members using the CFHT data to study their disk properties using the Spitzer data. Ongoing investigations include searches for members via emission line spectra (Knapp et al., in prep), Herbig-Haro (HH) objects (Stapelfeldt et al. in prep), and transition disks (McCabe et al. in prep).

In this paper, we select new candidate Taurus members with infrared excesses using Spitzer and Two-Micron All-Sky Survey (2MASS; Skrutskie et al. 2006) data. We construct color-magnitude and color-color diagrams for point sources, then use the locations of previously-identified young stars in these diagrams to select new candidate members with infrared excesses. To discard obvious extragalactic sources, we examine the source morphology in all available bands of the multiwavelength Taurus survey. We construct spectral energy distributions (SEDs) from the photometry over all available bands, again discarding objects we believe to be galaxies. Follow-up spectroscopy has been obtained to assess whether or not our new candidate Taurus objects are likely Taurus members. We also present Spitzer flux densities for the 215 previously-identified members found in the region covered by our Spitzer survey. Note that (a) the 215 previously-identified objects include those members without infrared excesses identified via other mechanisms; (b) the 215 previously-identified objects are those covered by our Spitzer map – there are other legitimate Taurus members outside the region we observed, such as in L1551; (c) our new candidate member list is necessarily just those with IR excesses and exclusively within the regions covered by our Spitzer observations. Some objects are resolved in one or more of the Spitzer images, and extended source photometry may be a better representation of the complete flux from the object; many of the extended sources are discussed individually in other papers (e.g., Tobin et al. 2008, Stapelfeldt et al. in prep)

The observations, data reduction, and ancillary data are described in §2. Section 3 describes our young stellar object (YSO) selection process which is based on the colors of previously-identified Taurus members, also presented here. We describe 34 objects that we have, thus far, identified as new members of Taurus (plus 3 probable new members and 10 possible new members) in §4 and discuss the properties of the new objects in conjunction with (and comparison to) the previously-identified members of Taurus. Finally, we summarize our main points in §5. The Appendix contains spectral energy distributions and discussion of some specific objects.

2 Observations, Data Reduction, and Ancillary Data

2.1 Spitzer data

P08 and P09 present a comprehensive discussion of the Spitzer data acquisition, reduction, and bandmerging to the 2MASS data. In summary, we conducted the observations using IRAC (Infrared Array Camera; 3.6, 4.5, 5.8, & 8 m; Fazio et al. 2004) and MIPS (Multi-band Imaging Photometer for Spitzer; 24, 70, & 160 m; Rieke et al. 2004) in two epochs to enable removal of asteroids from the final point-source catalog. The observations were spread over three observing programs and three years, 2005 to 2007.

For IRAC, we used MOPEX (MOsaicking and Point source EXtractor; Makovoz & Marleau 2005) to find the sources, and IDL to perform aperture photometry at those locations. With our IRAC observations, we sacrificed redundancy for spatial coverage, and obtained just 2 IRAC frames per position (total integration time of 25.2 seconds), so instrumental artifacts are abundant. We discarded single-band (apparent) detections as likely artifacts. Objects that we measured to be brighter than the 0.6 sec saturation limits (630, 630, 4600, and 2500 mJy at the four IRAC channels) we took to be saturated, and these appear as lower limits in our catalog. The zero-points we used to convert between flux densities and magnitudes were as found in the IRAC Data Handbook on the SSC website: 280.9, 179.7, 115.0, and 64.13 Jy for IRAC’s four channels, respectively.

For MIPS, we used MOPEX point-response-function (PRF) fitting photometry at 24 and 70 m. The total integration time at 24 m was 30 seconds per position; the MIPS scan legs were interleaved to provide complete coverage at 70 m, and a total integration time of 15 seconds per position. We took objects brighter than 4.7 Jy at 24 m and 6.5 Jy at 70 m to be saturated (or at least non-linear). These objects appear in our catalog as having lower flux density limits. Following the MIPS Data Handbook on the SSC website, the zero-points that convert between flux densities and magnitudes are 7.14 and 0.775 Jy for MIPS-24 and 70.

The observations at 160 m present special challenges. All of the things that can affect the other bands (such as saturation, extended emission, confusion with the cloud background and nearby objects – whether they be Taurus or background objects – and instrumental artifacts), also affect this band. Because the Taurus cloud emission and instrumental effects are both very strong, and because the resolution is the poorest of all the Spitzer bands, these items are of particular concern at this bandpass. Additionally, due to scattered data gaps in our 160 m map (see P08,P09), measurements (or limits) at 160 m are missing or compromised for some sources. MOPEX does not detect any point sources automatically at 160 m, because all detected point-like objects appear to be slightly resolved. For 100 objects that were apparent by eye in the 160 m image (or for which limits were of interest for this paper), we performed aperture photometry on the cleaned image which was smoothed by a 4 pixel median filter to minimize the influence of holes in the map and image artifacts. We used a 32 aperture, an annulus from 64-128, and an aperture correction of 1.97 (valid for temperatures between 500 and 2000 K40). Based on a comparison of the flux densities obtained from the filtered image and the unfiltered image, we took the flux density uncertainties to be 20% below 5 Jy and 30% for higher flux densities. Some objects that fell in regions with too many missing flux density values (from saturation or gaps in the map) are not retrievable and thus do not have a measurement (or limits); in essence, they are off the edge of the map. Visual inspection of each 160 micron source was used in order to determine whether the object was clearly detected as a single point source, confused with another nearby source, or contaminated by data dropouts and/or saturation issues which would cause the reported flux density to be a lower limit; these are indicated in the data tables below. The zero-point for MIPS-160 is 0.159 Jy, again from the MIPS Data Handbook on the SSC website.

We extracted  data from the 2MASS point source catalog for our region, retaining flux densities only for those objects with high-quality 2MASS data flags. There were a handful of objects of interest for this paper for which we made the following manual modifications, and therefore these modified values were used for the color-magnitude diagrams (CMDs) and spectral energy distributions (SEDs) below. Measurements for five objects did not meet the data flag criteria we imposed on the 2MASS catalog, but their as-reported flux densities were completely consistent with the rest of their SED, so we adopted their measurements as good detections; these objects are SST Tau 041542.7+290959, 041542.7+290959, 042517.6+261750, 043835.4+261041, and 043354.7+261327. Flux densities for one or more bands for the following previously-identified Taurus members do not exist in the point source catalog, and thus the flux densities used below were taken from the extended source catalog: SST Tau 042757.3+261918, 044112.6+254635, 043535.3+240819, and 043316.5+225320.

We bandmerged all the available point sources between 2 and 70 microns using position matching alone, with a wavelength-dependent maximum matching radius. Sources between 2 and 8 m were matched over a radius of 1, and at 24 m, the matching radius to the rest of the catalog was 2. All matching radii are values empirically determined by inspection of histograms of nearest neighbors between bands, and spot-checking individual sources; histograms of positional offsets and additional discussion appears in P09. We pre-merged the 24 and 70 m catalogs before merging to the rest of the catalog using an empirically-determined radius of 10. Because the spatial resolution of the 70 m images is so much worse than the 2 m images, often more than one NIR (or optical) source can be matched to the 70 m source; however, it is extremely likely that if we detect a source at 70 m, it will also appear at 24 m, so by implementing the pre-merge of 24 and 70 m, we are preferentially matching the 70 m sources to a likely physical match.

We include here a brief aside on the accuracy of blind merging by position. In the generic case of surveys across wavelengths, relative astrometric accuracy and spatial resolution is paramount. In our case of a catalog primarily driven by Spitzer+2MASS sources, astrometric accuracy is not the dominant source of error, since each instrument is internally consistent and calibrated to the 2MASS coordinate system. For many star-forming regions studied with Spitzer, e.g., many of those observed by the Cores-to-Disks (c2d; Evans et al. 2003) and Gould’s Belt (Allen et al. in preparation) projects, the source surface density is high enough that blind merging by position causes an unacceptable rate of false matches, and multiple short-wavelength sources should in reality be assigned to a single long-wavelength source. However, the source surface density in Taurus is low enough (4 sources per square arcminute, compared to 20 in some star-forming regions) that source confusion in general is not as much of a concern. On the other hand, in Taurus, many objects are known to be close binaries, and we do not apportion the flux density we observe between the two objects; for close binaries, we have treated the object as single here. In any case, in three of the objects investigated in detail for this paper (1% of the objects investigated, 0.5% of the total number of 70 m sources in the entire catalog), we determined by individual inspection that the 24/70 flux densities were incorrectly matched to a nearby faint short-wavelength source, rather than the correct, bright, slightly farther away, short-wavelength source. In these cases, we manually tweaked the flux assignment; the position change is well within the expected uncertainties between the long- and short-wavelength catalogs. We are confident that for the large majority of the sources in our entire catalog, our blind merging by position works, but for any particular source not discussed here, the images and the flux assignment in our delivered catalogs should be carefully scrutinized.

In creating our Spitzer-centric catalog, we dropped any object without a Spitzer detection (e.g., sources off the edges of our maps) before proceeding and after each additional merging step below (e.g., when combining the SDSS catalog and the Spitzer catalog, we did not retain SDSS-only sources from off the edges of our map or whose SED falls so rapidly that they are too faint for our shallow Spitzer survey). There are nearly 700,000 sources in the catalog with Spitzer flux densities in at least one band. This does not include the asteroids, which will be discussed by Hines et al., in preparation. It also does not include sources that are substantially extended (except at 160 m, see below); many of those will be covered by Stapelfeldt et al., in preparation. The vast majority of the 700,000 sources are well behind the Taurus Molecular Cloud. Sources which are members are generally expected to be bright in the shorter bands and detected in multiple bands.

P09 discusses the survey sensitivity in detail. In summary, the 3.6 and 4.5 m sensitivities are quite comparable, and 98% of the objects detected in 3.6 m are also detected at 4.5 m. The 5.8 and 8 m channels are much less sensitive; only 22% of the objects detected at 3.6 m are also detected at 5.8 m, and just 17% of the objects detected at 3.6 m are also detected at 8 m (where nebulosity can also be a factor in point source identification and extraction). Our 24, 70, and 160 m sensitivity is a strong function of position in the image because of nebular and high Zodiacal dust emission contributions to the background. In part because of the varying background but also because of the effective sensitivity of the instrument to photospheres at the distance of Taurus given our exposure times, just 1.4% of the objects detected at 3.6 m are also detected at 24 m, and just 0.15% are detected at 70 m. The faintest independent 24 m detection is 10th mag (M2 spectral type photosphere at Taurus age and distance), and the histogram of detections turns over at 9.3 mags (e.g., there is a steep fall-off between [24]9.3 and 10, where the bracket notation denotes the magnitude at that band). Similarly, at 70 m, the faintest object is [70]3.5, and a more typical value is 2.5-2.7 (note that 70 m is much more strongly affected by nebular emission and instrumental effects than 24 m). Only O or B photospheres would be that bright at the distance of Taurus, so we can only detect legitimate Taurus objects at 70 (or 160) m which have substantial IR excesses.

A full completeness analysis is given by P09, but as another independent way of assessing our completeness, we examined by hand each of the images at each of the Spitzer bands for each of the previously identified Taurus members and new candidate Taurus members discussed here (see §3.1.1 and §3.1). If the object could be seen in the image but a flux density was not initially reported at that band, we made a manual assessment of the flux density or upper/lower limit, as appropriate. For IRAC, 1-2% (depending on the band) of the previously identified Taurus members and 4-11% of the new candidate members were missing photometry and were filled in manually (having lower signal-to-noise). The most common band in which flux densities were erroneously missing (e.g., not in the automatically generated catalog but visible in the images) was 5.8 m, which is not particularly surprising, as this is the least sensitive of the IRAC bands. For MIPS, 9% of the previously identified Taurus members were missing photometry in either 24 or 70 m, and 6% of the new candidate objects were missing photometry at 24 or 70 m. The lower fraction of missing photometry in the new candidate objects as compared to the previously identified objects is a reflection of the fact that our selection mechanism is somewhat biased towards objects with MIPS detections; see §4.1 below.

Many sources detected at shorter wavelengths are undetected at longer wavelengths, and it is important for our science analysis to obtain upper limits for our sources in the Spitzer photometric bands. For the list of coordinates of previously identified and new candidate Taurus members, at 24 m, we used MOPEX to look for a source whose photometry could be obtained via PRF-fitting at that location. If an object was detected, we took a weighted average flux density based on all detections (e.g., between epochs and tiles). If the final signal-to-noise ratio (SNR) was 3, we took the error to be the 1 upper limit, and multiplied by 3 to get the 3 limits found in the data tables below and SEDs in §A. If the PRF fitting failed, we performed aperture photometry at the location of the object (at each tile and epoch available), and took a weighted average of all the resultant positive aperture flux densities. If that average had a SNR 3, we took that weighted average to be a detection. For all objects that had SNR3, we took the upper limit to be the 1 limit (and multiplied by 3 to get the 3 limits found in the data tables and SEDs below). If all the measured aperture flux densities were negative, we took the 1 limit to be the straight average of the errors (and multiplied by 3 to get the 3 limits found in the tables and SEDs below). Finally, still at 24 m, the objects that cannot be resolved from a companion are reported as simply unknown, where the presence of a companion is known from shorter-wavelength higher-spatial-resolution observations. At 70 m, some objects are unresolved from a nearby object and are impossible to estimate (again, where the presence of a companion is known from shorter-wavelength higher-spatial-resolution observations). Upper limits at 70 m for all remaining undetected sources were obtained by performing aperture photometry at the expected source location, using a 35 aperture and a multiplicative aperture correction of 1.22, as discussed in the MIPS Data Handbook, available at the SSC website. These 1- errors were multiplied by 3 to get the 3- errors shown in the Tables and Figures here. Upper limits at 160 m were individually assessed using aperture photometry on the uncertainty image using the same parameters as for detected sources above (32 aperture, an annulus from 64-128, and an aperture correction of 1.97) to obtain 1- errors, and then multiplied by 3 to get the 3- errors shown in the Tables and Figures here.

2.2 Complementary survey photometric data

In §2.1, above, we discussed merging the 2MASS and Spitzer data. We also need to match our catalog to the other Taurus surveys, listed in §1 above. Again, we match by position, with a radial offset tolerance customized empirically to each band or catalog.

The extracted CFHT point sources (see Monin et al. in preparation or Guieu et al. 2006 for more details on the extraction process; also see Monin et al. 2007 or Guieu 2008) are merged first to 2MASS. Sources that are CFHT-only are then dropped in order to remove objects that are very statistically likely to be instrumental artifacts. The CFHT sources are then merged to the Spitzer catalog. The CFHT bandpass is converted to Cousins via the following equation:

(1)

and then converted to flux densities using the Cousins zero-point from Bessell (1979), W m Hz. For these points, we use the effective wavelength of 0.79 m. About 138,000 of the point sources in our catalog have CFHT magnitudes (20% of the entire catalog).

The SDSS photometry arrives from the SDSS pipeline with photometric measurements in in flux density units of nanomaggies41, which can be converted to the same flux density units as the rest of the catalog data. We retained only those flux density measurements with good quality flags, and we merged the source lists for each of the SDSS tiles to each other by position to remove duplicates before merging to the master Spitzer catalog. The effective wavelengths are 3590, 4810, 6230, 7640, and 9060 Å for , respectively. We also made note of whether the object appearing in the SDSS images was flagged by the pipeline as extended or not. There are SDSS -band flux densities for about 300,000 objects in our catalog (45% of the entire catalog). There are 6400 spectra available from SDSS, about 3400 of which overlap the Spitzer survey region; for each object, we matched by position to our Spitzer catalog, and accepted the spectral classification produced by the SDSS pipeline as a spectral classification of the object, unless another spectral classification was available in the literature (see below).

There are 1000 objects in our catalog (0.1% of the entire catalog) with X-ray measurements from the XEST survey (Güdel et al. 2007). The XEST catalog includes flux densities from the XMM-Newton Optical Monitor (OM). The OM has a field of view comparable to, but not exactly identical to, the main X-ray field of view; see Audard et al. (2007) for more discussion of the XEST-OM sample. These data are in one of three ultraviolet bandpasses (, UVW1, or UVW2). To convert these values to flux densities, we used the following equation, found in the XMM-Newton OM calibration document (Chen et al. 2004):

(2)

where is the reported magnitude (and the flux density) for a given object, = 18.259, 17.204, and 14.837, and = 1.94, 4.76, and 5.71 ergs cm s Å counts sec for , UVW1, and UVW2 (respectively). In the equation, is in units of Å, and is Å s The effective wavelengths are 0.344, 0.291, and 0.212 m for , UVW1, and UVW2. There are 1600 objects with XMM-Newton OM flux densities in our catalog (0.2% of the entire catalog).

We note that many of the X-ray detected XEST sources are likely background galaxies (see Güdel et al. 2007) and that XEST included regions not covered by our map, such as L1551.

The XEST team assembled a catalog of supporting data from the literature, such as optical photometric measurements, for all of the previously-identified Taurus members (see §3.1.1 below); we have included these photometric points in our database, converting Johnson magnitudes to flux densities using zero-points available in the literature (e.g., Cox 2001 and references therein).

The SEDs presented in this paper use all of these supporting data where available (except for the X-ray fluxes), and are presented as in cgs units (erg s cm), against in microns.

2.3 Spectroscopy

We obtained follow-up spectroscopy for 75% of the candidate YSOs discussed in this paper. Some previously identified Taurus members missing spectral types in our database (as discussed in §3.1.1 below) were also observed. Data were obtained over six runs between 2007 and 2009 at Keck and the Palomar 200. Most of the 200 spectra are low-resolution optical, obtained with the Double Spectrograph at Palomar (30 Nov - 3 Dec 2008) or LRIS at Keck (Feb 2007). Many spectra were taken in the infrared with Triplespec at Palomar (21-24 Nov 2008 and 21 Dec 2008) or NIRSPEC at Keck (Dec 2007 and Feb 2008). The infrared spectra will be discussed in a forthcoming paper; the optical spectra are discussed here.

The optical spectra from Palomar are taken in two segments, blue and red; the blue covered 3710-5660 Å at 2 Å/px and the red, 6230-8720 Å at 2.5 Å/px. Instrument settings were a 316 lines mm grating blazed at 7500 Å and used at grating angle 24.75 for the red side, and a 300 lines mm grating blazed at 3900 Å and used at grating angle 23.12 for the blue side. LRIS at Keck is also a double-barreled spectrograph which we used with a 400 lines mm grism blazed at 3400 Å in the blue and a 400 lines mm grating blazed at 8500 Å and positioned at grating angle 23.49 in the red. We obtained continuous wavelength coverage from the blue atmospheric cutoff to 9400 Å at 1.86 Å px. The Double Spectrograph and LRIS data were both reduced using the Image Reduction and Analysis Facility (IRAF)42 ccdred and onedspec packages. Images were trimmed, bias-subtracted, and flattened prior to spectral extraction with the IRAF task apall. Wavelength calibration was performed using a Fe-Th-Ar lamp in the blue and Th-Ar lamp in the red. The wavelength solution was applied using the IRAF task dispcor. The white dwarf Feige 34 was observed each night, providing an approximate flux calibration reference for all the scientific targets.

Spectral classification was obtained via visual examination of each spectrum and comparison to a standard grid composed of 60 stars ranging in types from B8 to M9. Four authors performed the classification independently to achieve an estimated accuracy of roughly a subclass.

The red spectra included H. For each spectrum, we used IRAF to measure an equivalent width for H, following the usual convention where negative values indicate emission (see §4.1). We also noted if the Ca IR triplet was in emission at the time of observation; this is indicated in the data tables below.

The spectroscopic data are sufficient to rule out redshifted galaxies, to classify stars, and to find stars with H in emission. However, our data are of insufficient resolution to, e.g., detect the presence of lithium, or determine surface gravities for most types. Section 4.1 discusses an analysis similar to that presented by Slesnick et al. (2008) which uses the TiO 8465 Å index and Na 8190 Å index to determine an estimate of the surface gravity of the star. Additional follow-up data will be required to assess membership for stars with no H in emission and a small IR excess at Spitzer bands, and/or types earlier than M1 where the gravity analysis is not applicable.

3 YSO candidate selection

3.1 Overview of YSO selection process

First, we establish two comparison samples from the literature, and then we discuss the process by which we selected new candidate YSOs in Taurus.

Template sample of previously-identified Taurus members

We first informed our search for new Taurus members by determining the regions of color space occupied by previously identified Taurus members. By “Taurus member,” we mean an object that is confirmed via multiple mechanisms to be young and associated with the Taurus Molecular Cloud and the other Taurus members, e.g., sharing communal properties such as stellar activity. By “previously identified,” we mean identified as a member by other authors in the literature using data sets other than the Taurus Spitzer Legacy Survey. However, in order to appear in our catalog, the object must be within the region we mapped with Spitzer. There are legitimate Taurus members outside our region, including, e.g., those in the L1551 region.

The core of our sample of previously-identified Taurus members is the list assembled by the XEST team for their analysis (see Güdel et al. 2007 and references therein). We have updated this list with more recently confirmed objects (e.g., Scelsi et al. 2008), as well as scattered additional previously-identified Taurus members found in the literature. Kenyon et al. (2008) also report previously identified Taurus objects, with 30 more objects in our Spitzer field of view, which we have also included (but see Appendix B.7 for one object from Kenyon et al. (2008) which we rejected). We have thus defined our sample of previously identified Taurus members as basically an updated XEST+Kenyon et al. list convolved with our survey coverage. There are 215 previously-identified Taurus members in our Spitzer maps. There are 100 more objects from Kenyon et al. which are outside our mapped region. Binary objects that are unresolved in any of our Spitzer maps are regarded here as a single object (e.g., FS Tau Aab, whose separation is ). We discuss the overall Spitzer properties of this list in some detail below. We note here that all of these 215 previously-identified Taurus members were detected by Spitzer, but not all of them have IR excesses; this list includes the young stars without IR excesses (e.g., mostly weak-lined T Tauri stars, WTTS) discovered by other means.

Hartmann et al. (2005) report IRAC observations of a set of previously identified members covered by IRAC guaranteed time observation (GTO) team observations. This region of the sky is also covered by our shallower map, to the same depth as the rest of our survey. Our photometry agrees within the errors expected from photometry methodology and from the intrinsic variability of the stars.

We do not include the objects reported by Luhman et al. (2006, 2009a,b) as previously known objects because they were found with an independent analysis of the same data used here – our Taurus Legacy data, in part along with the XEST data – and the derived values agree.

Scelsi et al. (2008) present spectroscopic follow-up on potential new Taurus members discovered by the XEST survey (Scelsi et al. 2007). Three confirmed new Taurus members from Scelsi et al. (2008) were independently discovered and confirmed by us using Spitzer data (SST Tau 043456.9+225835 = XEST 08-003, SST Tau 043542.0+225222 = XEST 08-033, and SST Tau 042215.6+265706 = XEST 11-078). Since we report these in the list of new Taurus members, these do not appear in the list of previously identified Taurus members; they are noted in the tables below. The new members reported there that we did not rediscover are included in our list of previously identified Taurus members. A complete discussion of the Spitzer properties of all of the candidate members found using XEST X-rays that were presented by Scelsi et al. (2007) will appear in Audard et al., in preparation.

Template sample of non-members

Aside from previously-identified Taurus members, there are a large variety of other previously-identified objects in our survey region. Many of these are clearly not Taurus members, but some are more ambiguous. The previously-identified objects include known extragalactic objects, named objects of unknown nature, confirmed non-members, and potential (unconfirmed) members of Taurus.

To construct this list, we first searched in SIMBAD over our entire field to obtain a list of 8000 known objects. For objects that did not already have high-precision coordinates, we went back to the original article reporting the discovery of the object and attempted re-identification of the object using finding charts and 2MASS images. If no finding charts were available, the brightest close object from 2MASS was assigned to the object’s name. Some objects are not recoverable, but most were identified; nearly 90% of the entire 8000-object list has high-accuracy coordinates in the end. New coordinates were reported back to the SIMBAD team for inclusion in their database.

We also included the results from several papers from the literature reporting specifically confirmed non-members. These confirmed non-members can be candidate member objects from other Taurus surveys such as Luhman et al. (2006) or Scelsi et al. (2008), that failed a spectroscopic test for membership. They can also be spectroscopically confirmed background giants from studies of the ISM (e.g., studies of the Taurus dark cloud). These confirmed non-members have not necessarily been ingested into SIMBAD, since they were not the primary scientific result of the paper. Note that we did not list as non-members those objects merely assumed but not confirmed (via spectroscopy) to be background giants.

We merged this list by position with our master catalog to identify objects seen in our survey. For each object for which a match was found in our catalog, we went back to the original literature in an attempt to identify it as a known extragalactic object, a named object of unknown nature (e.g., objects from an all-sky survey where no specific follow-up has been done), a confirmed non-member (as defined immediately above), or a potential (unconfirmed) member of Taurus. In the case of objects from the literature listed as potential but unconfirmed Taurus members, we noted and bookkept these objects separately, and we mention them where relevant below; some are indeed recovered here by our Spitzer-based searches for YSOs.

Thus, the sample of Taurus non-members is certainly biased and far from comprehensive and is defined to include mixtures of stars, other Galactic objects (such as planetary nebulae), and extragalactic objects. This sample can be indicative of some typical colors to expect from a variety of types of infrared-bright non-member objects.

As a further diagnostic for non-members (including extragalactic objects), we merged by position to the 2MASS extended object catalog. Objects in this catalog are likely but not guaranteed to be all extragalactic objects – 11 (out of 215) previously identified Taurus members are also 2MASS extended objects (due to, e.g., scattered light from extended dust structures), but 107/148 previously-known galaxies are 2MASS extended objects. 2MASS extended object identifications, if relevant, are noted in the data tables and SEDs below.

The Process

In order to find new candidate Taurus members, we first examined various color-color and color-magnitude spaces using our entire Taurus catalog, highlighting the locations of the previously identified objects (both members and non-members). We compared these diagrams to discussions in the literature also seeking to identify YSOs from Spitzer photometric measurements (e.g., Allen et al. 2004, Padgett et al. 2008b, Rebull et al. 2007, Harvey et al. 2007, Gutermuth et al. 2008). There is no single color selection criterion that is 100% reliable in separating members from non-member contaminants. Exactly which color selection criteria work best can be a strong function of the relative bandpass sensitivities and saturations, since 2MASS, IRAC, and MIPS do not all detect the same faintest objects (due not only to sensitivities but also degree of interstellar reddening and embeddedness of the young protostellar objects), or saturate for the same brightest objects. After extensive empirical investigation using diagrams from the literature as well as new diagrams, we selected four color-magnitude diagrams (CMDs) and one color-color diagram (CCD) which provided the best diagnostics for YSOs, and we used them to construct an initial list of new candidate YSOs. In each diagram, we define regions most likely to harbor YSO candidates, and regions most likely to contain galaxies or other non-members; these are listed in detail in §3.1.5.

By imposing these color selections, we are selecting objects that have infrared excesses (e.g., flux densities above that expected for a photosphere) and whose overall brightness is consistent with objects at the Taurus distance. We interpret these excess objects as dusty objects, with circumstellar disks and/or envelopes. We do not select objects without infrared excesses.

One aspect of our survey which makes it different from many of the Spitzer-based surveys in the literature is our extensive optical imaging. While the SDSS and CFHT imaging data do not cover every square arcminute of the Spitzer maps, they cover most of it. The SDSS spatial resolution is only slightly better than the IRAC resolution at 1.4, but the CFHT data has much better spatial resolution at . We examined the images at all available bands for each of the nearly 900 objects meeting the color-color or color-magnitude criteria (plus many more objects in the process of establishing these color spaces). At any band, if the object is a resolved galaxy, or projected in the vicinity of a galaxy cluster, we dropped it from further consideration. Some of the objects that are resolved are actually previously-identified YSOs. Many of the objects that have Spitzer colors similar to YSOs turn out to be resolved galaxies when examined with SDSS or CFHT. These optical imaging data have been crucial to our ability to distinguish galaxies from YSO candidates.

If the candidate object meets the color criteria in any one of the color-magnitude spaces we investigated and passes the imaging/spatial resolution test, we regard it as a provisional YSO candidate, pending additional scrutiny discussed below. Objects meeting the color criteria but failing the imaging/spatial resolution test are “candidate non-members” and appear separately in the Figures below.

Gradations of Confidence for YSO candidates

Previously identified Taurus members tend to be bright, because previous infrared (and optical) surveys were shallower than our surveys. True new Taurus members are also likely to be generally bright. Very red (embedded or cool) objects could also be members, especially since this survey goes fainter in the infrared than any prior survey of the region (excepting the Spitzer GTO observations in the various core regions, Hartmann et al. 2005). However, the fainter objects are also statistically more likely to be galaxies, especially over our survey area of more than 44 square degrees at galactic latitude. Thus, we specifically focused our attention on bright and/or red objects meeting our color selection criteria. Faint red objects meeting our color selection criteria were also considered but are statistically more likely to be galaxies than YSO Taurus members.

In addition to the easily quantifiable Spitzer magnitude and color criteria, we also individually assessed each candidate YSO using qualitative judgments. These include but are not limited to: morphology in imaging data in each available band; relative brightness at all bands from to 160 m (e.g., infrared excess, but optical too bright to be a Taurus member); amplitude of excess; shape of SED; apparent (projected) proximity to other previously identified Taurus members; apparent (projected) proximity to clearly-identifiable galaxies (e.g., appearing to be part of a galaxy cluster); resolvable spiral arms or tidal tails; previous identifications (e.g., with the 2MASS extended source catalog); estimated  from the 160 m map (e.g., objects seen in high extinction regions are likely Taurus members); and star counts (a similar criterion to proximity to galaxies or estimated ). These assessments were done over several weeks by groups of co-authors and resulted in increased appreciation of the range of contaminants, and more objects being identified as new likely galaxies. (See the Appendix discussion on “8 m pop-up objects,” §B.7, for an example of a class of objects we rejected.) We looked critically at the shape of the excess above the photosphere, and if the excess appeared only at one band (8 or 24 m), we retained the object as a YSO candidate only if it was more than 4 above the photosphere (see §B.5 for many of the rejected low-significance sources). For the surviving YSO candidates, based on all of the available information from any wavelength (spectroscopic as well as photometric, plus derived information such as placement in a theoretical Hertzprung-Russell Diagram – see §4.6) as well as all the criteria listed above, we assigned a letter grade, A/B/C, with grades of “A” as more likely members than those with grades of “C.”

These qualitative criteria can fail to recover some of the previously-identified Taurus members. Several of the previously-identified Taurus members do not have IR excesses and are therefore not recoverable by our search. Seven of the previously-identified Taurus members (e.g., 042146.3+265929 or 042307.7+280557) would probably have been rejected because in the optical images, these objects are in front of a field of galaxies, i.e., they appear to be part of a galaxy cluster, and are not in a high  region. One additional previously identified member, the well-known edge-on disk IRAS 04302+2247 (=SST Tau 043316.5+225320), was temporarily identified as a galaxy because its appearance was so unusual in the optical image. While our process is clearly imperfect, we are confident that, working as a group and using all of the available multi-wavelength information, we have identified a reasonably high-confidence sample of candidate Taurus members present in our photometric catalog.

Our approach for finding YSOs is customized to our data set. This labor-intensive process is not one that can be blindly applied to other regions, even regions where similar extensive supporting optical data are available. While our color selection can be easily applied to any Spitzer+2MASS catalog, the manual examination of each object is not necessarily easily duplicated and certainly automating this process is not currently possible. However, because our survey is wide-area, and the contamination rate is high, this process is unavoidable and has been crucial to our YSO selection. The time we spent in vetting the candidate list enabled more efficient use of our follow-up spectroscopic telescope time, e.g., there was little time wasted in taking spectra of contaminants.

The Figures and Sample Selection Criteria

sample selected via… YSO selection faint flag
24/70 CMD either [24]7 OR [24][70]6 [24]7
/24 CMD 14 AND [24]1 13.5
8/24 CMD [8][24]0.5 AND [8]9.5
( ([8][24]4 and [8]10) or ([8][24] 4 and [8]2.5([8][24])) )
4.5/8 CMD [4.5] 6 AND [4.5]11
( [4.5] 6 and [4.5] 11.5
and [4.5][8] 0.4) OR ( [4.5] 11.5 and [4.5] 0.6944([4.5][8])+11.22)
IRAC CCD [3.6][4.5] 0.15 and [5.8][8] 0.3 and [3.6] 13.5
Table 1: Sample Selection Criteria

The color-color and color-magnitude spaces we have chosen to use (see §3.1.3 for overview) are the following: [24] vs. [24][70] (§3.2.1),  vs. [24] (§3.2.2), [8] vs. [8][24] (§3.2.3), [4.5] vs. [4.5][8] (§3.2.4), and finally, [3.6][4.5] vs. [5.8][8] with an additional [3.6] brightness cutoff (§3.2.5). Table 1 summarizes the details of the sample selection criteria for each parameter space. Our final selection includes objects selected in any of these parameter spaces (not just objects selected in all of them); this will be discussed in more detail in §4.1. (We explicitly compare this selection method to others from the literature in §4.7 below.) We discuss each of these parameter spaces, in the order given above and in Table 1, in §3.2.1-3.2.5; for each, there is a figure (Figures 1-5) consisting of 6 panels. Each of the panels contains either a subsample or a comparison sample to clearly demonstrate our selection techniques. In the remainder of this section, we discuss each of the panels in introductory terms only.

In the upper left of each Figure is the SWIRE (Spitzer Wide-area Infrared Extragalactic Survey; Lonsdale et al. 2003) ELAIS N1 extragalactic field43 (the c2d reduction – see Evans et al. 2007 – is used here, as in Rebull et al. 2007 and Padgett et al. 2008b). The ELAIS N1 field is a 6 square degree field centered on 16h08m44s +56d26m30s (J2000), or galactic coordinates () of 86.95, +44.48 (to be compared with the Taurus map center of 173,15). The SWIRE sample is expected to be essentially entirely galaxies and foreground stars, and as such provides a visual guide to the locations where such objects appear in the corresponding diagram. Note that this is just the 6 square degree field, as observed; it has not been scaled up to represent 44 square degrees of Taurus data, because in this case we are primarily interested in the range of colors sampled by the galaxies, not the overall numbers. As we will see below, many newly discovered extragalactic objects in our survey have colors very similar to many certifiable YSOs, and different than the colors of objects found in SWIRE. Note also the Galactic latitude difference; this difference in Galactic latitude is likely to dominate the source counts in IRAC bands 1 and 2. More discussion of relative source counts will appear in P09.

In the upper right panel of each Figure, our entire Taurus catalog is represented, so that various sub-samples can be seen in the context of the larger catalog. The Taurus catalog is expected to consist of YSOs, foreground/background stars (and other non-stellar galactic objects such as planetary nebulae), and background galaxies (recall that the asteroids have already been removed). To first order, then, the objects in the Taurus catalog that do not resemble the objects found in SWIRE are the YSOs. However, the populations are not necessarily well-separated, as can be seen in the remaining panels of the Figures.

The remaining 4 panels in each Figure are subsets of the Taurus catalog. The second row of plots contains YSOs, both the previously identified Taurus members (left) and new candidate Taurus members (right), those selected by that particular diagram () as well as others selected from other diagrams (grey dots). The distribution of previously identified Taurus members includes those selected based on infrared excess and those selected via other mechanisms, and thus includes objects without IR excesses; of course, we will not find objects like the latter using Spitzer. Note also that the distribution of previously identified Taurus members often includes objects that have colors resembling galaxies. This is not surprising, since the galaxies are indeed undergoing star formation; thus, these color selection mechanisms are successfully finding star formation, just not necessarily in Taurus. The set of new candidate Taurus members is constructed from a color and magnitude cut on the entire sample, and then examining all of the available data for each of the candidates, dropping the likely galaxies (§3.1.4).

The third and final row contains the distributions for non-members, both previously identified and newly identified here. The left panel is the sample of previously identified non-members which, as discussed in §3.1.2, includes stars identified via proper motions, background giants, and galaxies identified in the literature. The last panel is the sample of all objects identified as possibly YSOs based on Spitzer colors but then rejected as such, based primarily on inspection of the optical images and SEDs; see §3.1.4. Objects which passed all the other tests to be YSO candidates but failed the spectroscopic test (see §2.3) are indicated in the last two panels of the Figures by grey stars. (Note that, having been selected by the other tests, they also appear in the 4th panel as candidate YSOs.)

Thus, for the color-magnitude or color-color space represented by each Figure, one can examine and compare the distribution of galaxies (SWIRE, previously identified non-members, new non-members), the distribution of YSOs (previously identified Taurus members), the distribution of foreground/background stars (SWIRE, previously identified non-members), and the distribution of new candidate Taurus members.

sample 24/70 /24 8/24 4.5/8 IRAC ANY objects identified
CMD CMD CMD CMD CCD objects identified in ALL diag.
initial sample size 447 357 381 334 266 883 103
Entire sample
# previously identified YSOs (all) 89 135 124 102 102 144 65
      (% out of CMD selection ) 19 37 32 30 38 16 63
      (% out of 215 previously identified YSO sample) 41 63 58 47 47 67 30
# new candidate YSOs (all) 34 85 81 65 57 148 16
      (% out of CMD selection ) 7 23 21 19 21 16 15
      (% out of 148 new candidate YSO sample) 22 57 55 44 39 100 11
# previously identified NM (all) 47 51 33 38 30 98 10
      (% out of CMD selection ) 10 14 8 11 11 11 9
      (% out of 821 previously identified NM sample) 6 6 4 5 4 12 1
# new NM (all) 270 92 147 121 72 487 12
      (% out of CMD selection ) 60 25 38 36 27 55 11
      (% out of 489 new NM sample) 55 19 30 25 15 100 2
# SWIRE (all; for comparison) 57 29 20 42 7 109 1
      (% out of entire SWIRE sample ) 3 1 0.9 2 0.3 5 0.04
Just the faint sample
# previously identified YSOs (faint) 0 3 15 5 1944 245
      (% out of CMD selection ) 0 0.8 3 1 246 147
      (% out of 215 previously identified YSO sample) 0 1 7 2 948 149
# new candidate YSOs (faint) 6 9 21 32 5650 451
      (% out of CMD selection ) 4 3 6 10 852 553
      (% out of 148 new candidate YSO sample) 4 6 14 22 3854 355
# previously identified NM (faint) 8 16 6 32 4956 857
      (% out of CMD selection ) 1 4 1 9 558 759
      (% out of 821 previously identified NM sample) 1 2 0.7 4 560 161
# new NM (faint) 156 43 110 111 37162 1163
      (% out of CMD selection ) 34 12 28 33 4264 1065
      (% out of 489 new NM sample) 32 9 22 23 7666 267
# SWIRE (all; for comparison) 40 15 13 24 107 1
      (% out of entire SWIRE sample ) 2 0.7 0.6 1 568 0.0469
Table 2: Sample properties I.70
property prev. ident. YSOs71 prev. ident. YSOs, bright72 new candidate YSOs new candidate YSOs, bright
total (fraction)73 total (fraction) total (fraction) total (fraction)
total sample size 215 (1.00) 196 (1.00) 148 (1.00) 92 (1.00)
having IRAC 3.6 m 193 (0.90) 174 (0.89) 142 (0.96) 86 (0.93)
having IRAC 4.5 m 189 (0.88) 170 (0.87) 145 (0.98) 90 (0.98)
having IRAC 5.8 m 212 (0.99) 193 (0.98) 147 (0.99) 91 (0.99)
having IRAC 8.0 m 206 (0.96) 187 (0.95) 147 (0.99) 92 (1.00)
having MIPS 24 m 173 (0.80) 154 (0.79) 135 (0.91) 82 (0.89)
having MIPS 70 m 95 (0.44) 89 (0.45) 35 (0.24) 17 (0.18)
having all 4 IRAC 187 (0.87) 168 (0.86) 141 (0.95) 86 (0.93)
having all 4 IRAC+MIPS 24 154 (0.72) 135 (0.69) 128 (0.86) 76 (0.83)
having both MIPS 89 (0.41) 83 (0.42) 35 (0.24) 17 (0.18)
having 209 (0.97) 194 (0.99) 140 (0.95) 92 (1.00)
having prior name 215 (1.00) 196 (1.00) 65 (0.44) 46 (0.50)
Table 3: Sample properties II.

3.2 Implementation of the Spitzer Selection Criteria

Selection via [24] vs. [24][70]

Figure 1: [24] vs. [24][70] for (TOP) the SWIRE sample (essentially all galaxies; contours at 1,2,4,8,16 objects), the entire Taurus sample (YSOs+contaminants; contours at 1,2,5,15,35; dotted line indicates region considered for YSO candidacy), (MIDDLE) the sample of previously-identified Taurus members, and the sample of all new candidate members ( = objects selected in this color-magnitude space; grey dots=objects selected based on other color-magnitude spaces; dotted line indicates region considered for YSO candidacy; dashed line indicates cutoff for “faint” flag), and (BOTTOM) the sample of previously-identified non-members (stars and galaxies) and the sample of new candidate non-members(stars and galaxies) ( = objects selected in this color-magnitude space; grey stars=objects selected as YSOs but spectroscopically confirmed to be non-members; dotted line indicates region considered for YSO candidacy).

The [24] vs. [24][70] diagram has been used before to find new candidate YSOs (e.g., Padgett et al. 2008b, Rebull et al. 2007). Figure 1 shows this color-magnitude diagram for the 6 samples mentioned in §3.1.5 above (left to right, top to bottom): SWIRE (expected to be essentially entirely galaxies), the entire Taurus sample, previously identified Taurus members, new candidate Taurus members, previously identified non-members (stars identified via proper motions, background giants, and galaxies identified in the literature), and new candidate non-members identified here.

By inspection of Figure 1, we find that objects with [24]7 and [24][70] between about 4 and 7 are statistically likely to be galaxies. Unadorned photospheres (e.g., old foreground stars) will be bright and have [24][70]0; an A3 ZAMS photosphere has [24]7 at the distance of Taurus, and for a median Taurus-age member, [24]7 corresponds to mid-K. Compared to the SWIRE catalog, the entire Taurus catalog contains many objects with similar colors, but also many objects that are similarly red and much brighter at [24], and therefore are candidate dusty young stars.

Based on the properties of the previously identified member and non-member samples, the properties of the SWIRE sample, and discussions in the literature, the selection we impose to search for new candidate YSOs is either [24]7 or [24][70]6. Statistics on this sample are given in Table 2 (along with statistics from the SWIRE sample for comparison); in summary, this cut yields 450 objects, each of which we investigated at all our available imaging bands; 20% of them are previously identified Taurus members, 7% of them survive the tests to be potential new YSOs, and 70% are previously identified or new non-member objects. Nearly all of the previously identified Taurus members that appear in this plot have [24]7. This is a likely bias in that all of the previous infrared surveys searching for Taurus members were much shallower than this Spitzer survey – the IRAS sensitivity limit was about 0.3 Jy, so we are going 7 magnitudes fainter than IRAS. However, in order to appear in this plot, the objects have to have been detected at 70 m as well, so the sensitivity of the 70 m survey is usually the limiting factor. Of the entire sample of previously identified Taurus members within our survey, 80% are detected at 24 m (see Table 3), and just 45% are detected at 70 m; 5% of the previously identified Taurus members are saturated in MIPS-24 and 3% are saturated in MIPS-70.

In this diagram, the set of previously-identified Taurus objects is generally distinguished from the distribution of faint objects found in the SWIRE sample. Fainter Taurus objects ([24]7) could exist, but objects that faint are statistically likely to be galaxies; their properties at other bands could suggest otherwise. Objects surviving the imaging test (and other qualitative criteria – see §3.1.4) but with [24]7 are therefore further identified as “faint.” About 17% of the 35 potential new YSOs in this parameter space are faint. Many of the other faint objects selected by our color/magnitude cut indeed resolve into galaxies when examined using the CFHT or SDSS imaging – 60% of all of the objects selected in this space are new galaxy candidates. About 100 of the brighter objects selected by this color cut resolve into galaxies, so faintness alone is insufficient for locating and identifying galaxies. As can be seen in Figure 1, most of the previously-identified non-members and new candidate non-members resemble the colors of objects found in SWIRE. Figure 1 and the statistics in Table 3 also demonstrate that our sample of candidate new YSOs is on average redder and fainter than the sample of previously identified YSOs.

As discussed above (§2.3), we have obtained Palomar and/or Keck spectroscopy of many of our candidate objects. Because this color selection uses bandpasses far from optical, these objects are often very faint indeed at optical or NIR bands. We have spectroscopy for about 70% of the 34 new candidate YSOs selected in this color space. So far, almost 90% of those are stellar (e.g., YSOs or stars that could still be shown to be foreground stars or background giants), and just 4 are confirmed to be extragalactic objects.

Selection via  vs. [24]

Figure 2:  vs. [24] for (TOP) the SWIRE sample (galaxies & foreground stars; contours at 1,2,4,8,16 objects), the entire Taurus sample (YSOs+contaminants; contours at 1,5,50,100,200 objects; dotted line indicates region considered for YSO candidacy), (MIDDLE) the sample of previously-identified Taurus members, and the sample of all new candidate members ( = objects selected in this color-magnitude space; grey dots=objects selected based on other color spaces; dotted line indicates region considered for YSO candidacy; dashed line indicates cutoff for “faint” flag), and (BOTTOM) the sample of previously-identified non-members (stars and galaxies) and the sample of new candidate non-members(stars and galaxies) ( = objects selected in this color-magnitude space; grey stars=objects selected as YSOs but spectroscopically confirmed to be non-members; dotted line indicates region considered for YSO candidacy).

As for [24] vs. [24][70], the  vs. [24] diagram has been used previously to find new candidate YSOs (e.g., Padgett et al. 2008b, Rebull et al. 2007). Figure 2 shows this color-magnitude diagram for the same samples as Fig. 1 (see §3.1). The SWIRE sample clearly (more obviously than the previous diagram) consists of both galaxies (14 and [24] between about 4 and 8) and stars (10 and [24]0). As before, the entire Taurus catalog has many objects with colors similar to the SWIRE sample, but also many objects that have properties different than the SWIRE sample, e.g., redder than [24]1 and brighter than 14, as well as redder than [24]8. Note that the lack of sources in the lower left of each panel is an artifact of the sensitivity limits of the survey.

The sample of previously identified Taurus members, for the most part, have 14, which generally avoids the region populated by galaxies in the SWIRE sample, but there are legitimate YSOs mixed in with the galaxies in this parameter space. Here too, the historical bias towards brighter objects in prior surveys can be seen, and faint red objects could be legitimate YSOs. Essentially all of the previously identified YSO sample has a  measurement in our database, but as mentioned above, just 80% are cleanly detected at 24 m (see Table 3). As above, fainter objects are statistically likely to be galaxies.

The selection we impose on this parameter space to search for new candidate YSOs is that 14 and [24] 1. Again, Table 2 summarizes the sample sizes; 360 objects meet these criteria, including most of the (detected) previously identified Taurus members; note that there are some stars without apparent IR excess (e.g., likely WTTS) with [24]0, and there are YSOs that have colors resembling galaxies. Note also that late-type stars do not have [24]=0 (Gautier et al. 2007). Objects with 13.5 are further identified as “faint” and thus statistically likely to be galaxies. Previously identified Taurus members compose 135 of the objects meeting the basic color criteria; about 50 are previously identified non-member objects, most of which are 2MASS extended sources (which could be galactic or extragalactic objects). By inspection of the individual images, about 100 of the objects selected here are clearly resolved galaxies. Besides the previously identified Taurus objects, 85 objects are indistinguishable from point sources, or have morphologies consistent with YSO candidates, and meet all the other qualitative criteria (see §3.1.4) for potential new YSOs selected via this color space; a quarter of these were already found via the 24/70 color magnitude diagram above.

In this parameter space, there is still a bias (relative to the previously identified Taurus member sample) towards finding red and faint objects, but this appears to be not nearly as strong as it was in the 24/70 space above. Of the 85 candidate YSOs found in this space, we have already obtained Palomar and/or Keck spectroscopy (see §2.3) for 85% of them. All of them except for 1 are stellar (e.g., YSOs or stars that could still be shown to be foreground stars or background giants); just 1 is rejected outright as a galaxy.

A relatively high fraction of literature background giants appear as selected in this parameter space. Because there is a large difference in wavelength between  and [24], this search is particularly sensitive to objects with small excesses, which could be interesting transition disk candidates. However, these objects could also be subject to reddening from the Taurus cloud that is high enough to significantly affect  but not 24 m, or Taurus cloud emission affecting the 24 m but not the  photometry – background giants are therefore potentially selected in this space. Several objects presented in the literature as candidate background objects based on shorter-wavelength photometric observations (i.e., without confirming spectroscopy) appear here as objects with potential excesses only at the longer wavelengths. With the information we have, we are unable to distinguish currently between transition disk candidates (i.e., Taurus objects with excesses only at 24 m) and confirmed background giants. These objects are all identified in Table 5 as candidate non-members which we have promoted to low-grade candidate YSOs. The SEDs that appear in Appendix A reveal that several of our candidate objects indeed have  values significantly affected by reddening and some candidate objects with clear cloud emission at 8 and/or 24 m are indicated in Table 7; also see §B.5 for discussion of objects with very small excesses, usually just at 24 m. We expect that several of the objects we have identified here will turn out to be background giants. Some candidate transition disk objects will be discussed in McCabe et al. (2009).

We note here that for surveys where the IRAC and MIPS coverage is well-matched, using [3.6] or even [4.5] in place of  for this color-magnitude space is likely to be a better choice for searching for YSOs for two reasons: (a) minimizing the influence of reddening on  (3.6 or 4.5 m is less affected by reddening than ; see Padgett et al. 2008b for more discussion on the influence of ), and (b) minimizing the intrinsic range of star colors – the intrinsic [24] color of M stars is not zero (Gautier et al. 2007) whereas [3.6][24] or [4.5][24] is zero for those stars. Specifically for our survey, the overall  towards Taurus is low, and all young stars at the distance of Taurus should be visible to 2MASS unless they are edge-on substellar objects. Moreover, using [3.6] or [4.5] in place of  does not reveal any YSO candidates not already selected by the color spaces used here, and finds in total only 2 more extragalactic objects. Had we used either [3.6] or [4.5] in place of , however, we would have found a factor of 4 fewer objects that we believe (based on inspection and our qualitative criteria) to be likely reddened background giant contaminants.

Selection via [8] vs. [8][24]

Figure 3: [8] vs. [8][24] for (TOP) the SWIRE sample (galaxies & foreground stars; contours at 1,2,4,8,16 objects), the entire Taurus sample (YSOs+contaminants; contours at 1,5,50,100,200 objects), (MIDDLE) the sample of previously-identified Taurus members, and the sample of all new candidate members ( = objects selected in this color-magnitude space; grey dots=objects selected based on other color spaces; dotted line indicates region considered for YSO candidacy; dashed line indicates cutoff for “faint” flag), and (BOTTOM) the sample of previously-identified non-members (stars and galaxies) and the sample of new candidate non-members(stars and galaxies) ( = objects selected in this color-magnitude space; grey stars=objects selected as YSOs but spectroscopically confirmed to be non-members; dotted line indicates region considered for YSO candidacy).

While essentially all of the previously identified YSOs have 2MASS detections at , some fainter legitimate YSOs may be embedded enough that the relatively shallow 2MASS survey will not detect the objects at , whereas they will be detected by our IRAC survey. Thus, we chose to investigate the [8] vs. [8][24] parameter space; see Figure 3.

The morphology of this space is similar to the  vs. [24] space, except the region occupied primarily by galaxies is now more elongated in color and has a more prominent slope towards fainter and redder objects. In order to select specifically for objects redder than most galaxies, the selection criteria we used consist of three line segments: (a) [8][24]0.5 to avoid the stars without excesses; and (b) ([8][24]4 and [8]10) to catch the bright stars in the middle of the plot; OR ([8][24] 4 and [8]2.5([8][24])) to obtain the reddest stars. Objects with [8]9.5 are statistically likely to be galaxies, and thus those are further identified as “faint” in Table 5.

About 380 objects in the catalog meet these criteria, 120 of which are previously identified YSOs, 180 of which are non-members (previously identified or new), and 80 of which survive the imaging test (and other qualitative criteria – see §3.1.4) and remain potential YSOs. Of these, 25 were already found using the [24] and [70] selection criteria (§3.2.1), 55 were found using  and [24] (§3.2.2), and 20 were found in all three color-magnitude planes.

There is an apparent gap in the last panel of Figure 3 inside the “galaxy blob” at [8][24]4 and [8]10. This is a direct result of our selection methodology. The fainter, bluer part of the distribution are largely those objects that were not obviously point sources in the optical imaging, and the redder part of the distribution closely tracks the (dotted) dividing line we used for our selection criteria. This population is composed of objects we rejected as candidate YSOs based on the qualitative criteria listed in §3.1.4 above.

We have followup spectroscopy (see §2.3) for 80% of the 81 new candidate YSOs selected in this color space. Nearly all (95%) of these are stellar; just 3 are rejected as galaxies.

Selection via [4.5] vs. [4.5][8]

Figure 4: [4.5] vs. [4.5][8] for (TOP) the SWIRE sample (galaxies & foreground stars; contours at 1,2,4,8,16 objects), the entire Taurus sample (YSOs+contaminants; contours at 1,10,100,1000,2000 objects; dotted line indicates region considered for YSO candidacy), (MIDDLE) the sample of previously-identified Taurus members, and the sample of all new candidate members ( = objects selected in this color-magnitude space; grey dots=objects selected based on other color spaces; dotted line indicates region considered for YSO candidacy; dashed line indicates cutoff for “faint” flag), and (BOTTOM) the sample of previously-identified non-members (stars and galaxies) and the sample of new candidate non-members(stars and galaxies) ( = objects selected in this color-magnitude space; grey stars=objects selected as YSOs but spectroscopically confirmed to be non-members; dotted line indicates region considered for YSO candidacy).

To this point, we have required MIPS-24 detections for YSO candidate selection, which strongly biased our sample of new potential YSOs towards the generally brighter and/or larger excess objects (by comparison to the rest of the catalog). As an example of how many YSOs we may be missing by requiring 24 m, just 80% of the previously identified YSOs are detected at 24 m. This results from a combination of intrinsic disk properties (where disk emission makes the objects easier to detect at 24 m) and the Spitzer sensitivity relative to low-mass photospheres at the Taurus distance (for those YSOs without disks). By loosening this restriction and not requiring MIPS-24, we extend the sample of potential objects, but also the potential contamination. We now investigate the [4.5] vs. [4.5][8] parameter space; see Figure 4. This parameter space, on its own, provides the largest possible initial sample size we have yet investigated, as 17% of the entire catalog is detected in these two IRAC bands (compared with just 2% of the entire catalog detected at MIPS-24; see P09 for additional similar statistics). To first order, the morphology of this space is similar to the other spaces we have investigated, with the photospheres clustering around [4.5][8]0 and the galaxies in a red and faint grouping. There are some new features apparent in this space, however. Saturation at 4.5 m occurs at 650 mJy (6.1 mags), so the locus of colorless objects is truncated at that level. In the sample of previously identified Taurus members, there is a clear distinction between the disked and non-disked population (a gap near [4.5][8]=0.5) which is not seen when considering the entire catalog.

The selection criteria we used to find candidate YSOs in this space selected the brighter and redder objects; we did this by stitching together several line segments. They are: (a) [4.5] 6 AND (b) ([4.5] 6 and [4.5] 11.5 and [4.5][8] 0.4) OR (c) ([4.5] 11.5 and [4.5] 0.6944([4.5][8])+11.22). About 335 objects meet these basic criteria, 100 of which are previously identified YSOs, and 160 of which are new or previously identified non-members. About 65 objects survive the imaging test (and other qualitative criteria – see §3.1.4) and are new candidate YSOs. The distribution of these objects in this color-magnitude space is very different than that for the previously identified members; these new objects are distinctly fainter and redder on the whole than the previously identified sample. Objects with [4.5]11 are given the “faint” flag in Table 5.

About a third of the new candidate YSO sample selected here are also retrieved from the 24/70 space above and about two-thirds are also retrieved from the /24 and 8/24 spaces above.

About 65% of these 65 candidate Taurus objects have Palomar and/or Keck spectroscopy (see §2.3), and nearly all are stellar; just 4 are dropped as galaxies.

Selection via IRAC color-color diagram

Figure 5: [3.6][4.5] vs. [5.8][8] for (TOP) the SWIRE sample (galaxies & foreground stars; contours at 1,2,4,8,16 objects), the entire Taurus sample (YSOs+contaminants; grey contours at 1,10,100,1000,2000 objects; solid line contours are for the entire Taurus sample with an additional [3.6]13.5, same contour limits as the grey contours), (MIDDLE) the sample of previously-identified Taurus members, and the sample of all new candidate members ( = objects selected in this color-color space; grey dots=objects selected based on other color spaces; dotted line indicates region considered for YSO candidacy), and (BOTTOM) the sample of previously-identified non-members (stars and galaxies) and the sample of new candidate non-members(stars and galaxies) ( = objects selected in this color-color space; grey stars=objects selected as YSOs but spectroscopically confirmed to be non-members; dotted line indicates region considered for YSO candidacy). An additional [3.6] brightness cut was also imposed on the YSO selection in this color space; see text.

As our final selection mechanism, we use the IRAC color-color diagram (as seen in, e.g., Allen et al. 2004). This parameter space, on its own, provides an initial sample size comparable to the previous 4.5/8 color selection, as 13% of the entire catalog is detected in all 4 IRAC bands (to be compared with just 2% of the entire catalog being detected at MIPS-24, and 17% detected at 4.5 and 8 microns; see P09 for additional similar catalog statistics). However, by using the IRAC color-color diagram on its own, we are blind to any luminosity information about the sources. This information was present previously because we were using color-magnitude, not color-color, diagrams. Given the surface density of galaxies, as well as the fact that the galaxy/YSO separation is not as vivid in this parameter space, the luminosity information is crucial. We imposed a requirement of [3.6] 13.5, and the cut we used on the IRAC color-color space was (based on literature discussions) [3.6][4.5] 0.15 and [5.8][8] 0.3. This approach is different than in our consideration of the above parameter spaces, where we specifically called out YSO candidates fainter than a specific level.

Using these criteria, 265 objects are selected, 100 of which are previously identified Taurus members, 100 of which are non-members (previously identified or new), and 65 of which are new candidate YSOs. Of those, 35% were also found using 24/70, 60% were found using /24 or 8/24, and 80% were found using 4.5/8. (More on objects selected using all CMDs in §4.1 below.)

As can be seen in Figure 5, the previously identified Taurus members roughly fall into two groups – those with little or no IRAC excess, and those with substantial excesses. Among our new candidate members, we have some objects with little or no IRAC excess (selected from other parameter spaces), as well as objects with more substantial excesses, but the division is not as clean, suggesting contaminants in our YSO candidate list. We have also selected some objects that are very red in [5.8][8] but nearly colorless in [3.6][4.5]. These could be disks with large inner holes, or galaxies.

A little more than half of these 57 candidate objects have spectroscopy (see §2.3) from Palomar and/or Keck; just 4 are galaxies.

3.3 Tables of objects

Now that we have used the Spitzer properties of the previously-identified Taurus member sample to select a new candidate YSO sample, we present the data tables with observed and derived properties of both sets of objects. In this section, we review the contents of Tables 48. The contents of Tables 4 and 5 are similar but not identical, as are the contents of Tables 6 and 7. Table 8 summarizes the new members, sorted by confidence level.

Tables 4 and 5 present, for each of the previously identified Taurus members and the new candidate Taurus members identified here, respectively, SST Tau names (note, as IAU-compliant names, the Right Ascension and Declination as given in the name are truncated, not rounded), a common name from previous studies (if applicable), and measurements in the Spitzer bands. For most of these objects, this is the first time that MIPS flux densities have appeared in the literature. Since many of the previously identified and new candidate Taurus members appear as having YSO-like colors in more than one of the color-magnitude and color-color diagrams of Table 1 and Figures 1-5, Tables 4 and 5 also present the color criteria that are met by each object individually, for each of the color spaces we use here to identify YSO candidates. Objects appearing faint and red (see §3.1.4 above) are indicated as such. SEDs for each of the previously identified members and new candidates appear in Appendix A; the SED properties of the sample as whole will be discussed in §4.5 below. Table 5 additionally contains notes about individual objects. These tables are sorted by SST Tau name, effectively sorted by RA and then Dec.

Additional information about each of the previously identified Taurus members and the new candidate Taurus members identified here appears in Tables 6 and 7, respectively. Both of these tables start by repeating the SST Tau name, and a previous common name (if applicable). Table 7 then lists the grade ranking (see §3.1.4 above) that we assigned each of the candidate objects. Note that these tables are still sorted by position; Table 8 later presents the candidate Taurus members in order of confidence.

We compare our search method to others in the literature in §4.7 below; in preparation for that, Tables 6 and 7 indicate, for each of the previously identified Taurus members, how (or if) the c2d (Harvey et al. 2007) or Gutermuth et al. (2008) criteria for YSOs identified the object. (NB: whether or not our search recovered each previously identified object can be found in Table 4.)

Tables 6 and 7 contain a YSO classification. The near- to mid-IR slope of each SED, , is what we used for determining a YSO classification for these objects. For each of the previously identified and new candidate objects in our survey, we performed a simple ordinary least squares linear fit to all available photometry (just detections, not including upper or lower limits) between 2 and 24 m, inclusive. Note that errors on all of the infrared points are so small as to not affect the fitted SED slope, and that a forthcoming paper will investigate the (small) effects of fitting a line to all available points within a different wavelength range, e.g., 3.6 to 24 m. In the spirit of Wilking et al. (2001), we define , where for a Class I, 0.3 to 0.3 for a flat-spectrum source, 0.3 to 1.6 for a Class II, and 1.6 for a Class III. We realize that the precise definition of can vary, resulting in different classifications for certain objects; detailed discussion of this issue is beyond the scope of this paper. Classification via this method is provided for all previously identified and new candidate objects specifically to enable comparison within this paper via internally consistent means.

Adopted spectral types appear in Tables 6 and 7. This spectral type comes from the literature (see §3.1.1) or from our spectra (§2.3); if the latter, it is indicated as such in the “notes” column. If we obtained a spectrum for the object, and if H was measurable, we report the equivalent width in these Tables (see §2.3 for analysis details). If the Ca infrared triplet was in emission at the time of our observation, it is noted in the “notes” column.

Tables 6 and 7 include an estimate of the star’s luminosity () and an estimate of the ratio of the infrared excess luminosity to the star’s total (photospheric+infrared) luminosity (, where ). We describe briefly our procedure to determine the infrared luminosity. Many faint sources were undetected at the longest wavelengths; we extrapolated missing data points for wavelengths longer than 8.0 m. We used the longest wavelength available data point as a reference and assumed that its flux density corresponded to blackbody emission peaking at that wavelength. We then used this blackbody function to estimate the missing fluxes at the longer wavelengths. We compared the measured colors and the expected photospheric colors (as tabulated in Chapter 7 of Allen’s Astrophysical Quantities; Cox 2001), attributing any difference to extinction, , and we corrected the photometric fluxes for it. We obtained a spline curve through the corrected fluxes in , space on a wavelength grid from 0.1 Å to 1000 Å with a  Å. To determine the infrared excess, we determined the underlying stellar photospheric emission using PHOENIX stellar atmosphere models for  K and Kurucz models for  K and matched the stellar atmosphere model to the corrected -band fluxes. The infrared luminosity was calculated by measuring the difference between the spline curve and the stellar atmosphere model. We emphasize that care was taken to ensure that we included only adequate excess luminosity contributions at each wavelength of the grid (e.g., if the stellar atmosphere model showed a drop in flux between the  and m fluxes, and the spline curve was above but there was no obvious sign of infrared excess at those wavelengths, the contribution to the infrared luminosity was not included). We also only included contributions if the spline curve was at least 1.5 times larger than the stellar atmosphere contribution. Finally, we determined if the calculated infrared luminosity was an upper limit by checking that at least one of the corrected photometric fluxes beyond m were real and not extrapolated. If the latter, the infrared luminosity was indicated as an upper limit. Note that this method is subject to several caveats: (a) objects that do not have spectral types (particularly common in the list of new candidate objects) do not have a calculated , and therefore no or ; (b) this method of dereddening using ignores the potential for near-IR excess (as well as veiling and the H-opacity minimum at 1.6 m) and therefore this method can overestimate ; (c) YSOs intrinsically vary at essentially all the wavelengths used here, and the photometry across the SED for each object was not obtained contemporaneously. Our values for are probably good to a factor of 2, and are sufficient to determine if a source has an envelope, is an optically thick disk only, a highly flattened / thinning disk, or a debris-like system. (See §4.6 for more discussion.) This approach is demonstrably inaccurate in comparison to more complex methods, such as those employing bolometric corrections to reddening-corrected flux densities in well-calibrated passbands. However, more detailed modeling is beyond the scope of this paper.

For the 148 new candidate Taurus members, Table 7 also contains an adopted membership classification indicating whether or not we regard the object as a Taurus member. This classification combines information from all of the available photometric and optical spectroscopic data (see §4.1 and §3.1.4). Extragalactic objects are noted as “xgal.” Objects that we believe to be reliable new members are indicated as “new member.” Objects that we think are likely to be new members but there is still some doubt are listed as “probable new member.” Objects with the next gradation of confidence are “possible new members.” Objects for which we have spectra but cannot determine clear membership are listed as “needs additional followup” and, finally, objects with no spectroscopic data yet are “pending followup.” There are 34 new members, 3 probable new members, 10 possible new members, 7 extragalactic objects, 2 other objects, 60 stars needing additional follow-up observations, and 33 pending any follow-up observations. Note that while all the “new members” are also grade A objects, not all grade A objects are “new members”, because of the need for additional data in many cases.

A final data table, Table 8, lists the new members in order of quality, sorted by their category (new member, probable new member, possible new member, needs additional followup, or pending followup), and then by our rank (and then by catalog number), such that the objects we grade as most likely to be new members appear at the top of the list. Table 8 also contains the projected angular separation from to the nearest previously-identified Taurus object.

SST Tau name common name [3.6] [4.5] [5.8] [8] [24] [70] [160] ident. in ident. in ident. in ident. in ident. in notes
(mag) (mag) (mag) (mag) (mag) (mag) (mag) 24/70 /24 8/24 4.5/8 IRAC
CMD CMD CMD CMD CCD
041314.1+281910 LkCa 1 8.54 0.05 8.50 0.05 8.41 0.05 8.43 0.05 8.28 0.08 1.30 no no no no
041327.2+281624 Anon 1 7.23 0.05 7.24 0.05 7.17 0.05 7.08 0.05 6.95 0.05 1.27 no no no no
041353.2+281123 IRAS04108+2803 A 9.02 0.05 8.37 0.05 7.67 0.05 6.57 0.05 3.44 0.04 0.19 -2.05 yes yes yes yes b
041354.7+281132 IRAS04108+2803 B 9.38 0.05 8.03 0.05 6.96 0.05 5.78 0.05 1.38 0.04 -1.84 0.22 -1.94 yes yes yes yes yes b
041357.3+291819 IRAS04108+2910 7.48 0.05 6.84 0.05 6.26 0.05 5.54 0.05 3.13 0.04 1.15 0.22 -3.39 yes yes yes yes yes
041411.8+281153 J04141188+2811535 10.93 0.06 10.40 0.05 10.12 0.07 8.99 0.06 5.76 0.01 1.03 yes yes yes yes
041412.2+280837 IRAS04111+2800G 13.19 0.06 11.90 0.06 11.19 0.06 10.39 0.06 3.47 0.04 -0.33 0.22 yes yes–faint yes–faint yes
041412.9+281212 V773 Tau ABC 6.62 6.10 5.13 0.05 4.38 0.05 1.69 0.04 0.27 0.22 yes yes yes
041413.5+281249 FM Tau 8.09 0.05 7.67 0.05 7.36 0.05 6.42 0.05 2.92 0.04 1.07 0.22 yes yes yes yes yes
041414.5+282758 FN Tau 7.59 0.05 7.17 0.05 6.71 0.05 5.75 0.05 2.03 0.04 -0.25 0.22 yes yes yes yes yes
041417.0+281057 CW Tau 6.62 6.10 5.08 0.05 4.51 0.05 1.75 0.04 -0.42 0.22 yes yes yes
041417.6+280609 CIDA-1 8.67 0.05 8.13 0.05 7.59 0.05 6.71 0.05 3.53 0.04 1.28 0.22 yes yes yes yes yes
041426.2+280603 IRAS04113+2758 A 6.62 6.10 4.63 0.05 3.79 0.05 0.45 -2.54 0.22 -4.35 0.34 f
041430.5+280514 MHO-3 7.22 0.05 6.49 0.05 5.75 0.05 4.53 0.05 0.45 -1.06 0.22 -4.15 0.34 yes yes
041447.3+264626 FP Tau 8.11 0.05 7.86 0.05 7.60 0.05 7.27 0.05 4.25 0.04 1.22 0.22 yes yes yes yes yes
041447.8+264811 CX Tau 8.48 0.05 8.13 0.05 7.68 0.05 6.63 0.05 3.35 0.04 1.23 0.22 yes yes yes yes yes
041447.9+275234 LkCa 3 AB 7.28 0.05 7.33 0.05 7.27 0.05 7.23 0.05 7.07 0.05 1.17 no no no no
041449.2+281230 FO Tau AB 7.53 0.05 7.17 0.05 6.72 0.05 5.92 0.05 2.83 0.04 0.79 0.22 yes yes yes yes yes
041505.1+280846 CIDA-2 8.90 0.05 8.79 0.05 8.71 0.05 8.68 0.05 8.45 0.11 1.31 no no no no
041514.7+280009 KPNO-1 13.23 0.13 12.72 0.22 12.94 0.09 12.81 0.10 10.61 0.90 no no
041524.0+291043 J04152409+2910434 11.86 0.05 11.79 0.05 11.66 0.06 11.48 0.06 10.06 1.14 no no
041612.1+275638 J04161210+2756385 9.38 0.05 9.04 0.05 8.71 0.05 8.30 0.05 5.37 0.04 1.55 0.22 yes yes yes yes yes
041618.8+275215 J04161885+2752155 10.88 0.05 10.78 0.05 10.67 0.06 10.68 0.06 9.95 1.26 no no
041628.1+280735 LkCa 4 8.18 0.05 8.17 0.05 8.04 0.05 8.05 0.05 7.94 0.07 1.20 no no no no
041639.1+285849 J04163911+2858491 10.50 0.05 10.14 0.05 9.86 0.05 9.41 0.05 7.22 0.05 1.24 yes yes yes yes
041733.7+282046 CY Tau 7.87 0.05 7.53 0.05 7.27 0.05 6.72 0.05 4.42 0.04 1.87 0.22 -1.41 yes yes yes yes yes
041738.9+283300 LkCa 5 8.93 0.05 8.80 0.05 8.66 0.09 1.61 no
041749.5+281331 KPNO-10 10.82 0.05 10.36 0.05 9.81 0.05 8.89 0.05 5.96 0.04 1.92 0.22 yes yes yes yes yes
041749.6+282936 V410 X-ray 1 8.41 0.05 7.85 0.05 7.42 0.05 6.47 0.05 3.78 0.04 2.95 0.22 yes yes yes yes yes
041807.9+282603 V410 X-ray 3 10.04 0.05 9.94 0.05 9.90 0.06 9.80 0.05 9.27 0.21 1.79 yes yes–faint no no
041817.1+282841 V410 Anon 13 10.23 0.05 9.94 0.05 9.49 0.05 8.81 0.05 6.04 0.04 -0.57 yes yes yes yes
041822.3+282437 V410 Anon 24 9.84 0.05 9.54 0.05 9.34 0.05 9.38 0.05 9.29 0.10 1.60 1.50 yes no no no
041829.0+282619 V410 Anon 25 8.87 0.05 8.64 0.05 8.46 0.05 8.39 0.05 8.15 0.08 1.67 0.12 yes no no no
041830.3+274320 KPNO-11 10.71 0.05 10.59 0.05 10.60 0.06 10.50 0.06 10.01 1.46 no no
041831.1+282716 V410 Tau ABC 7.36 0.05 7.34 0.05 7.34 0.05 7.25 0.05 7.14 0.06 1.65 no no no no
041831.1+281629 DD Tau AB 6.62 6.10 5.29 0.05 4.48 0.05 1.75 0.04 -0.04 0.22 yes yes yes
041831.5+281658 CZ Tau AB 8.46 0.05 7.63 0.05 6.62 0.05 5.00 0.05 1.96 0.04 1.45 0.22 yes yes yes yes yes
041832.0+283115 IRAS04154+2823 7.57 0.05 7.07 0.05 6.12 0.05 5.52 0.05 1.91 0.04 -0.38 0.22 yes yes yes yes yes
041834.4+283030 V410 X-ray 2 8.35 0.05 8.09 0.05 7.80 0.05 7.55 0.05 3.41 0.04 0.31 0.22 yes yes yes yes no
041840.2+282424 V410 X-ray 4 8.91 0.05 8.64 0.05 8.44 0.05 8.43 0.05 8.09 0.08 1.60 -2.59 yes no no no
041840.6+281915 V892 Tau 6.62 6.10 3.61 0.05 3.52 0.45 -2.30 -4.90 c d
041841.3+282725 LR1 9.50 0.05 8.92 0.05 8.44 0.05 7.95 0.05 4.65 0.04 0.38 0.22 -0.29 yes yes yes yes yes
041842.5+281849 V410 X-ray 7 8.73 0.05 8.61 0.05 8.35 0.05 8.09 0.07 5.15 0.01 -0.30 -2.88 yes yes yes no
041845.0+282052 V410 Anon 20 11.01 0.05 10.74 0.05 10.55 0.06 10.57 0.06 10.20 0.49 -3.20 no no
041847.0+282007 Hubble 4 7.09 0.05 7.04 0.05 6.95 0.05 6.96 0.05 6.78 0.01 0.18 -4.19 no no no no
041851.1+281433 KPNO-2 12.25 0.05 12.11 0.06 12.02 0.06 11.84 0.07 9.59 1.59 no no
041851.4+282026 CoKu Tau/1 10.22 0.05 9.02 0.05 7.72 0.05 5.87 0.05 1.07 0.04 -0.98 0.22 -2.55 yes yes yes yes yes c
041858.1+281223 IRAS04158+2805 9.23 0.05 8.54 0.05 7.85 0.06 6.84 0.05 2.73 0.04 -0.07 0.22 -2.51 0.22 yes yes yes yes yes
041901.1+281942 V410 X-ray 6 8.76 0.05 8.67 0.05 8.54 0.05 8.26 0.05 3.82 0.04 0.69 0.22 yes yes yes yes no
041901.2+280248 KPNO-12 13.97 0.06 13.61 0.06 13.23 0.08 12.75 0.08 10.13 1.74 -0.54 no no
041901.9+282233 V410 Tau X-ray 5a 9.64 0.05 9.55 0.05 9.43 0.05 9.39 0.05 8.88 0.12 1.59 -1.28 yes yes no no
041912.8+282933 FQ Tau AB 8.78 0.05 8.42 0.05 8.12 0.05 7.41 0.05 4.85 0.04 2.16 0.22 yes yes yes yes yes
041915.8+290626 BP Tau 7.27 0.05 6.90 0.05 6.65 0.05 5.71 0.05 2.52 0.04 0.71 0.22 yes yes yes yes yes
041926.2+282614 V819 Tau 8.20 0.05 8.29 0.05 8.11 0.05 8.06 0.05 6.29 0.05 yes yes no no
041935.4+282721 FR Tau 9.42 0.05 8.93 0.05 8.25 0.05 7.27 0.05 4.84 0.04 3.14 0.22 yes yes yes yes yes
041941.2+274948 LkCa 7 AB 8.11 0.05 8.11 0.05 8.04 0.05 7.99 0.05 7.75 0.06 1.94 no no no no
041942.5+271336 IRAS04166+2706 12.84 0.06 11.32 0.05 10.49 0.06 9.75 0.06 2.93 0.04 -1.92 0.22 -4.53 0.34 yes yes–faint yes–faint yes
041958.4+270957 IRAS04169+2702 8.41 0.05 7.15 0.05 6.29 0.05 5.33 0.05 0.66 0.04 -2.30 -5.40 0.34 yes yes yes yes
042025.5+270035 J04202555+2700355 10.99 0.05 10.77 0.05 10.44 0.06 9.74 0.05 6.13 0.04 2.49 0.22 yes yes yes–faint yes yes
042039.1+271731 2MASS J04203918+2717317 9.42 0.05 9.39 0.05 9.35 0.05 9.29 0.05 8.83 0.10 1.50 no no no no
042107.9+270220 CFHT-19 7.54 0.05 6.66 0.05 6.01 0.05 5.10 0.05 1.61 0.04 -1.18 0.22 -3.27 yes yes yes yes yes c
042110.3+270137 IRAS04181+2654B 9.03 0.05 8.24 0.05 7.60 0.05 6.70 0.05 2.69 0.04 -0.47 0.22 -3.97 yes yes yes yes yes b c
042111.4+270109 IRAS04181+2654A 8.60 0.05 7.56 0.05 6.71 0.05 5.71 0.05 1.64 0.04 -1.04 0.22 -4.21 0.34 yes yes yes yes yes b
042134.5+270138 J04213459+2701388 9.86 0.05 9.65 0.05 9.35 0.05 8.98 0.05 7.18 0.05 1.64 yes yes yes yes
042146.3+265929 CFHT-10 11.54 0.05 11.32 0.05 11.05 0.06 10.45 0.06 7.26 0.05 1.45 yes no yes–faint yes
042154.5+265231 J04215450+2652315 13.22 0.06 13.12 0.06 12.90 0.07 12.80 0.08 10.50 0.22 1.66 yes–faint no no no
042155.6+275506 DE Tau 7.07 0.05 6.73 0.05 6.40 0.05 5.78 0.05 2.58 0.04 -0.19 0.22 yes yes yes yes yes
042157.4+282635 RY Tau 6.62 6.10 3.60 0.05 3.52 0.45 -2.30 -4.24 0.34
042158.8+281806 HD283572 6.86 0.05 6.86 0.05 6.81 0.05 6.78 0.05 6.76 0.05 1.24 no no no no
042200.6+265732 FS Tau B 9.66 0.05 8.40 0.05 7.23 0.05 5.95 0.05 1.58 0.04 -0.68 0.22 -4.14 yes yes yes yes yes b c
042202.1+265730 FS Tau Aab 6.75 0.05 6.30 0.05 5.81 0.05 4.99 0.05 1.33 0.04 0.05 yes yes yes yes
042203.1+282538 LkCa 21 8.26 0.05 8.22 0.05 8.14 0.05 8.06 0.05 8.06 0.09 1.23 no no no no
042216.4+254911 CFHT-14 11.48 0.05 11.34 0.05 11.28 0.06 11.23 0.06 9.51 1.16 no no
042216.7+265457 CFHT-21 7.77 0.05 7.26 0.05 6.85 0.05 6.30 0.05 3.29 0.04 1.18 0.22 yes yes yes yes yes
042224.0+264625 2MASS J04222404+2646258 9.52 0.05 9.40 0.05 9.34 0.05 9.33 0.05 9.07 0.12 1.56 no no no no
042307.7+280557 IRAS04200+2759 8.43 0.05 7.81 0.05 7.28 0.05 6.44 0.05 3.23 0.04 0.76 0.22 yes yes yes yes yes
042339.1+245614 FT Tau 7.93 0.05 7.46 0.05 7.19 0.05 6.29 0.05 3.15 0.04 0.28 0.22 yes yes yes yes yes
042426.4+264950 CFHT-9 11.16 0.05 10.88 0.05 10.51 0.06 9.83 0.05 6.78 0.05 0.77 yes yes–faint yes yes
042444.5+261014 IRAS04216+2603 8.08 0.05 7.57 0.05 7.14 0.05 6.32 0.05 3.53 0.04 0.16 0.22 -2.47 0.22 yes yes yes yes yes
042445.0+270144 J1-4423 10.21 0.05 10.15 0.05 10.06 0.06 10.11 0.06 9.49 1.05 no no
042449.0+264310 RXJ0424.8 7.73 0.05 7.70 0.05 7.69 0.05 7.65 0.05 7.40 0.06 1.02 no no no no
042457.0+271156 IP Tau 7.77 0.05 7.45 0.05 7.24 0.05 6.60 0.05 3.48 0.04 0.74 0.22 yes yes yes yes yes
042517.6+261750 J1-4872 AB 8.21 0.05 8.20 0.05 8.08 0.05 8.06 0.05 7.77 0.07 1.10 no no no no
042629.3+262413 KPNO-3 11.41 0.05 10.99 0.05 10.49 0.06 9.72 0.05 6.86 0.05 1.09 yes yes–faint yes yes
042630.5+244355 J04263055+2443558 12.57 0.05 12.21 0.06 11.76 0.06 11.08 0.06 8.87 0.15 1.09 yes no no yes
042653.5+260654 FV Tau AB 6.62 6.10 5.23 0.05 4.56 0.05 1.54 0.04 -0.45 0.22 yes yes yes
042654.4+260651 FV Tau/c AB 8.01 0.05 7.58 0.05 7.05 0.05 6.29 0.05 3.88 0.04 0.72 -1.64 yes yes yes yes
042656.2+244335 IRAS04239+2436 7.61 0.05 6.32 0.05 5.38 0.05 4.50 0.05 0.45 -2.25 0.22 -4.63 0.34 yes yes
042657.3+260628 KPNO-13 8.75 0.05 8.33 0.05 7.99 0.06 7.35 0.05 5.32 0.04 0.93 -2.25 yes yes yes yes
042702.6+260530 DG Tau B 8.77 0.05 5.88 0.05 5.24 0.05 0.78 0.04 -2.24 0.22 -5.12 0.34 yes yes yes b
042702.8+254222 DF Tau AB 6.62 6.10 5.08 0.05 4.50 0.05 2.19 0.04 0.70 0.22 yes yes yes
042704.6+260616 DG Tau A 6.62 6.10 4.67 0.05 3.55 0.05 0.45 -2.30 -4.46 b c
042727.9+261205 KPNO-4 12.57 0.05 12.37 0.06 12.21 0.06 12.08 0.06 10.66 0.28 1.05 yes no no no
042745.3+235724 CFHT-15 13.24 0.06 13.15 0.06 13.25 0.07 13.05 0.10 10.55 1.06 no no
042757.3+261918 IRAS04248+2612 AB 9.83 0.06 9.10 0.05 8.28 0.05 7.10 0.05 2.27 0.04 -1.52 0.22 -4.39 0.34 yes yes yes yes yes
042838.9+265135 LDN 1521F-IRS 15.33 0.08 14.25 0.07 13.45 0.10 12.04 0.07 6.16 0.04 0.57 0.22 -4.28 0.34 yes yes–faint no no
042842.6+271403 J04284263+2714039 AB 9.76 0.05 9.53 0.05 9.21 0.05 8.83 0.05 6.21 0.05 0.88 yes yes yes yes
042900.6+275503 J04290068+2755033 12.30 0.05 11.99 0.05 11.60 0.06 10.92 0.06 8.06 0.07 0.88 yes no no yes
042904.9+264907 IRAS04260+2642 10.08 0.05 9.40 0.05 8.83 0.05 8.07 0.05 3.60 0.04 0.06 0.22 yes yes yes yes yes
042920.7+263340 J1-507 8.56 0.05 8.55 0.05 8.47 0.05 8.46 0.05 8.29 0.10 1.04 no no no no
042921.6+270125 IRAS04263+2654 8.06 0.05 7.67 0.05 7.31 0.05 6.69 0.05 3.41 0.04 1.11 0.22 yes yes yes yes yes
042923.7+243300 GV Tau AB 6.62 6.10 3.49 3.52 0.45 -2.30 -1.49 c d
042929.7+261653 FW Tau ABC 9.09 0.05 9.01 0.05 8.88 0.05 8.88 0.05 7.52 0.06 1.07 yes yes no no
042930.0+243955 IRAS04264+2433 10.21 0.05 9.43 0.05 8.60 0.05 6.72 0.05 1.12 0.04 -1.37 0.22 -1.94 yes yes yes yes yes
042941.5+263258 DH Tau AB 7.63 0.05 7.33 0.05 7.20 0.05 6.86 0.05 3.37 0.04 0.82 0.22 yes yes yes yes yes
042942.4+263249 DI Tau AB 8.21 0.05 8.22 0.05 8.14 0.05 8.11 0.05 0.72 no no
042945.6+263046 KPNO-5 11.05 0.05 11.02 0.05 10.94 0.06 10.83 0.06 9.71 0.90 no no
042951.5+260644 IQ Tau 6.81 0.05 6.37 0.05 6.07 0.05 5.53 0.05 2.82 0.04 0.32 0.22 yes yes yes yes yes
042959.5+243307 CFHT-20 9.02 0.05 8.55 0.05 8.32 0.05 7.84 0.05 4.91 0.04 2.06 0.22 yes yes yes yes yes
043007.2+260820 KPNO-6 13.12 0.06 12.77 0.06 12.42 0.06 11.58 0.06 9.20 0.19 1.01 yes–faint no no yes
043023.6+235912 CFHT-16 13.23 0.06 13.15 0.06 13.04 0.08 12.99 0.09 10.54 1.00 no no
043029.6+242645 FX Tau AB 7.22 0.05 6.96 0.05 6.69 0.05 5.97 0.05 3.03 0.04 1.09 0.22 yes yes yes yes yes
043044.2+260124 DK Tau AB 6.62 6.10 5.52 0.05 4.78 0.05 1.85 0.04 0.08 0.22 0.57 0.22 yes yes yes
043050.2+230008 IRAS04278+2253 6.62 6.10 3.49 3.52 0.45 -1.87 0.22 -3.88 0.34
043051.3+244222 ZZ Tau AB 8.08 0.05 7.90 0.05 7.61 0.05 6.94 0.05 4.53 0.04 0.72 -4.46 yes yes yes yes b
043051.7+244147 ZZ Tau IRS 8.11 0.05 7.38 0.05 6.73 0.05 5.78 0.05 2.01 0.04 -0.99 0.22 -3.61 0.22 yes yes yes yes yes b
043057.1+255639 KPNO-7 12.62 0.05 12.28 0.05 11.99 0.06 11.25 0.06 8.62 0.12 1.23 yes no no yes
043114.4+271017 JH56 8.72 0.05 8.75 0.05 8.66 0.05 8.60 0.05 6.76 0.02 0.75 yes yes no no
043119.0+233504 J04311907+2335047 11.66 0.05 11.53 0.05 11.56 0.06 11.46 0.06 10.59 0.86 no no
043123.8+241052 V927 Tau AB 8.52 0.05 8.47 0.05 8.38 0.05 8.38 0.05 8.19 0.09 0.91 no no no no
043126.6+270318 CFHT-13 12.90 0.06 12.75 0.06 12.72 0.07 12.70 0.07 10.72 0.29 0.68 yes no no no
043150.5+242418 HK Tau AB 7.71 0.05 7.35 0.05 7.10 0.05 6.58 0.05 2.31 0.04 -0.81 0.22 -3.02 0.22 yes yes yes yes yes
043158.4+254329 J1-665 9.35 0.05 9.29 0.05 9.24 0.05 9.22 0.05 9.04 0.17 1.08 no no no no
043203.2+252807 J04320329+2528078 10.30 0.05 10.20 0.05 10.13 0.06 10.09 0.06 9.67 1.03 no no
043215.4+242859 Haro6-13 6.62 6.10 5.49 0.05 4.85 0.05 0.88 0.04 -1.43 0.22 -4.02 0.34 yes yes yes
043217.8+242214 CFHT-7 AB 9.98 0.05 9.87 0.05 9.76 0.05 9.72 0.05 9.30 0.28 0.86 yes no no no
043218.8+242227 V928 Tau AB 7.86 0.05 7.82 0.05 7.72 0.05 7.64 0.05 7.54 0.06 0.84 no no no no
043223.2+240301 J04322329+2403013 10.89 0.05 10.83 0.05 10.79 0.06 10.67 0.06 9.82 0.91 no no
043230.5+241957 FY Tau 7.18 0.05 6.76 0.05 6.50 0.05 5.99 0.05 3.67 0.04 yes yes yes yes
043231.7+242002 FZ Tau 6.62 6.10 5.27 0.05 4.58 0.05 2.06 0.04 0.31 0.22 yes yes yes
043232.0+225726 IRAS04295+2251 8.63 0.05 7.72 0.05 6.83 0.05 5.32 0.05 1.40 0.04 -1.32 0.22 -3.93 0.34 yes yes yes yes yes
043243.0+255231 UZ Tau Aab 6.62 6.10 5.63 0.05 4.79 0.05 1.54 0.04 -0.69 0.22 -2.15 0.22 yes yes yes b
043249.1+225302 JH112 7.41 0.05 7.12 0.05 6.83 0.05 5.89 0.05 2.53 0.04 0.72 0.22 yes yes yes yes yes
043250.2+242211 CFHT-5 10.46 0.05 10.27 0.05 10.09 0.06 10.07 0.06 9.56 0.29 1.16 -1.44 yes no no no
043301.9+242100 MHO-8 9.32 0.05 9.21 0.05 9.14 0.05 9.09 0.05 8.92 0.15 0.88 no no no no
043306.2+240933 GH Tau AB 7.08 0.05 6.77 0.05 6.50 0.05 6.03 0.05 3.17 0.04 0.43 0.22 yes yes yes yes yes
043306.6+240954 V807 Tau AB 6.62 6.21 0.05 5.96 0.05 5.57 0.05 2.96 0.04 0.36 0.22 yes yes yes yes
043307.8+261606 KPNO-14 9.78 0.05 9.67 0.06 9.60 0.05 9.58 0.05 9.04 0.12 1.44 -1.91 yes yes–faint no no
043309.4+224648 CFHT-12 10.86 0.05 10.63 0.05 10.34 0.06 9.95 0.06 8.25 0.07 1.16 yes yes–faint yes yes
043310.0+243343 V830 Tau 8.41 0.05 8.41 0.05 8.37 0.05 8.32 0.05 8.14 0.08 1.03 no no no no
043314.3+261423 IRAS04301+2608 12.05 0.05 11.72 0.05 11.29 0.06 9.54 0.05 3.28 0.04 1.12 0.22 -0.95 yes yes yes–faint yes–faint yes
043316.5+225320 IRAS04302+2247 10.29 0.05 9.88 0.05 9.72 0.05 9.71 0.06 3.57 0.04 -1.88 0.22 -4.51 0.34 yes yes yes–faint no no
043319.0+224634 IRAS04303+2240 6.62 6.10 4.77 0.05 3.73 0.05 1.43 0.04 -0.11 0.22 yes yes yes
043334.0+242117 GI Tau 6.87 0.05 6.31 0.05 5.79 0.05 5.12 0.05 2.15 0.04 yes yes yes yes
043334.5+242105 GK Tau 6.62 6.10 5.79 0.05 5.14 0.05 1.70 0.04 -0.23 0.22 yes yes yes
043336.7+260949 IS Tau AB 7.85 0.05 7.46 0.05 6.94 0.05 6.03 0.05 3.65 0.04 2.08 0.22 -0.83 yes yes yes yes yes
043339.0+252038 DL Tau 6.95 0.05 6.37 0.05 5.92 0.05 5.13 0.05 2.19 0.04 -0.25 0.22 -2.44 0.22 yes yes yes yes yes
043342.9+252647 J04334291+2526470 12.76 0.06 12.63 0.06 12.52 0.07 12.47 0.07 11.05 1.43 no no
043352.0+225030 CI Tau 6.99 0.05 6.53 0.05 6.17 0.05 5.33 0.05 2.37 0.04 -0.80 0.22 yes yes yes yes yes
043352.5+225626 2MASS J04335252+2256269 8.79 0.05 8.71 0.05 8.63 0.05 8.60 0.05 8.32 0.09 1.41 no no no no
043354.7+261327 IT Tau AB 7.35 0.05 6.98 0.05 6.63 0.05 6.05 0.05 3.53 0.04 0.83 0.22 -1.28 yes yes yes yes yes
043410.9+225144 JH108 9.30 0.05 9.27 0.05 9.19 0.05 9.17 0.05 8.88 0.12 1.15 no no no no
043415.2+225030 CFHT-1 11.23 0.05 11.10 0.05 10.98 0.06 11.02 0.06 9.94 1.00 no no
043439.2+250101 Wa Tau 1 7.83 0.05 7.79 0.05 7.75 0.05 7.73 0.05 7.67 0.07 0.85 no no no no
043455.4+242853 AA Tau 7.29 0.05 6.84 0.05 6.44 0.05 5.65 0.05 2.81 0.04 -0.14 0.22 -2.47 0.22 yes yes yes yes yes
043508.5+231139 CFHT-11 11.19 0.05 11.12 0.05 11.04 0.06 10.99 0.06 10.23 0.20 0.37 yes no no no
043520.2+223214 HO Tau 8.90 0.05 8.52 0.05 8.38 0.05 7.73 0.05 4.85 0.04 2.43 0.22 yes yes yes yes yes
043520.8+225424 FF Tau AB 8.45 0.05 8.44 0.05 8.42 0.05 8.36 0.05 8.15 0.09 1.26 no no no no
043527.3+241458 DN Tau 7.47 0.05 7.16 0.05 6.78 0.05 6.03 0.05 3.04 0.04 0.44 0.22 0.04 yes yes yes yes yes
043535.3+240819 IRAS04325+2402 A 9.93 0.05 9.28 0.05 9.06 0.05 8.54 0.05 1.43 0.04 -2.26 0.22 -5.07 0.34 yes yes yes yes yes
043540.9+241108 CoKu Tau/3 AB 7.43 0.05 6.95 0.05 6.48 0.05 5.64 0.05 3.31 0.04 1.33 0.22 -2.14 yes yes yes yes yes
043541.8+223411 KPNO-8 11.64 0.05 11.54 0.05 11.43 0.06 11.46 0.06 10.71 1.12 no no
043545.2+273713 J04354526+2737130 13.18 0.06 13.11 0.06 12.93 0.07 13.07 0.11 10.62 1.47 no no
043547.3+225021 HQ Tau 6.62 6.10 5.61 0.05 4.47 0.05 1.65 0.04 -0.18 0.22 yes yes yes
043551.0+225240 KPNO-15 9.79 0.05 9.72 0.05 9.66 0.05 9.65 0.05 9.71 0.11 0.72 no no no no
043551.4+224911 KPNO-9 13.63 0.06 13.52 0.06 13.70 0.12 13.41 0.17 10.93 0.86 no no
043552.0+225503 2MASS J04355209+2255039 9.56 0.05 9.52 0.05 9.39 0.05 9.35 0.06 0.50 no no
043552.7+225423 HP Tau AB 6.62 6.20 0.05 5.65 0.05 4.88 0.05 1.49 0.04 -1.93 0.22 -4.48 0.34 yes yes yes yes
043552.8+225058 2MASS J04355286+2250585 9.46 0.05 9.36 0.05 9.28 0.05 9.29 0.05 9.10 0.13 0.93 no no no no
043553.4+225408 HP Tau/G3 AB 8.62 0.05 8.60 0.05 8.51 0.05 8.47 0.06 -0.03 -2.19 no no
043554.1+225413 HP Tau/G2 7.19 0.05 7.17 0.05 7.11 0.05 7.02 0.05 -0.03 -2.35 no no
043556.8+225436 Haro 6-28 AB 8.61 0.05 8.18 0.05 7.85 0.05 7.14 0.05 4.39 0.04 0.70 -2.24 yes yes yes yes
043558.9+223835 2MASS J04355892+2238353 8.15 0.05 8.19 0.05 8.10 0.05 8.06 0.05 1.12 no no
043610.3+215936 J04361030+2159364 13.02 0.06 12.74 0.06 12.41 0.06 11.74 0.06 9.01 0.18 1.07 yes–faint no no yes
043610.3+225956 CFHT-2 11.63 0.05 11.43 0.05 11.34 0.06 11.32 0.06 10.61 1.48 -3.51 no no
043619.0+254258 LkCa 14 8.52 0.05 8.54 0.05 8.51 0.05 8.45 0.05 8.24 0.10 0.99 -0.98 no no no no
043638.9+225811 CFHT-3 11.79 0.05 11.69 0.05 11.59 0.06 11.57 0.06 8.55 1.12 no no
043649.1+241258 HD 283759 8.32 0.05 8.25 0.05 8.30 0.05 8.20 0.05 6.64 0.05 1.10 0.22 0.51 yes yes yes no no
043800.8+255857 ITG 2 9.60 0.05 9.47 0.05 9.37 0.05 9.31 0.05 9.17 0.19 0.96 -2.05 no no no no
043814.8+261139 J04381486+2611399 10.80 0.05 10.21 0.05 9.64 0.05 8.92 0.05 4.98 0.04 0.80 -1.11 yes yes yes yes
043815.6+230227 RXJ0438.2+2302 9.69 0.05 9.69 0.05 9.64 0.05 9.60 0.05 9.35 1.08 no no
043821.3+260913 GM Tau 9.27 0.05 8.77 0.05 8.43 0.05 7.81 0.05 5.33 0.04 0.97 -1.31 yes yes yes yes
043828.5+261049 DO Tau 6.62 6.10 5.26 0.05 4.77 0.05 1.09 0.04 -1.37 0.22 -3.92 0.34 yes yes yes
043835.2+261038 HV Tau AB 7.65 0.05 7.59 0.05 7.49 0.05 7.46 0.05 0.72 -3.65 no no
043835.4+261041 HV Tau C 11.33 0.14 10.74 0.05 10.22 0.05 9.38 0.04 3.52 0.04 -0.09 0.22 yes no yes yes yes e
043858.5+233635 J0438586+2336352 10.51 0.05 9.84 0.05 6.39 0.05 0.85 yes
043901.6+233602 J0439016+2336030 9.76 0.05 9.18 0.05 6.28 0.05 2.30 yes
043903.9+254426 CFHT-6 10.75 0.05 10.45 0.05 10.02 0.06 9.14 0.05 6.51 0.05 0.47 -0.54 yes yes yes yes c
043906.3+233417 J0439064+2334179 10.73 0.05 10.62 0.06 9.32
043913.8+255320 IRAS04361+2547 AB 8.00 0.05 7.08 0.05 6.46 0.05 4.82 0.05 0.45 -2.30 -4.73 yes yes
043917.7+222103 LkCa 15 7.61 0.05 7.41 0.05 7.23 0.05 6.64 0.05 3.11 0.04 -0.40 0.22 -2.47 0.22 yes yes yes yes yes
043920.9+254502 GN Tau B 6.99 0.05 6.58 0.05 6.21 0.05 5.42 0.05 2.82 0.04 1.59 0.22 -2.43 yes yes yes yes yes
043935.1+254144 IRAS04365+2535 7.22 0.05 6.10 4.87 0.05 4.16 0.05 0.45 -2.17 0.22 -3.82 c
043947.4+260140 CFHT-4 9.54 0.05 9.07 0.05 8.60 0.05 7.78 0.05 4.95 0.04 0.91 -4.76 yes yes yes yes
043953.9+260309 IRAS 04368+2557 13.39 0.11 11.15 0.08 10.09 0.07 9.73 0.08 2.69 0.04 -2.30 -4.40 yes–faint yes–faint yes c d
043955.7+254502 IC2087 IRS 6.62 6.10 3.49 3.52 0.45 -2.17 0.22 -5.41 c
044001.7+255629 CFHT-17 AB 10.15 0.05 9.96 0.05 9.87 0.05 9.82 0.06 9.10 0.18 0.74 -2.26 yes yes–faint no no
044008.0+260525 IRAS 04370+2559 7.96 0.05 7.38 0.05 6.93 0.05 5.93 0.05 2.43 0.04 0.75 0.22 -1.78 yes yes yes yes yes
044039.7+251906 J04403979+2519061 AB 9.84 0.05 9.68 0.06 9.62 0.05 9.57 0.05 7.55 0.05 1.00 -2.43 yes yes–faint no no
044049.5+255119 JH223 8.90 0.05 8.60 0.05 8.24 0.05 7.74 0.05 5.13 0.04 2.20 0.22 0.93 yes yes yes yes yes
044104.2+255756 Haro 6-32 9.66 0.05 9.56 0.06 9.49 0.05 9.46 0.06 9.59 0.33 0.70 -0.83 no no no no
044104.7+245106 IW Tau AB 8.13 0.05 8.15 0.05 8.08 0.05 8.03 0.05 7.97 0.07 1.08 no no no no
044108.2+255607 ITG 33 A 9.68 0.05 9.05 0.05 8.49 0.05 7.73 0.05 4.60 0.04 0.67 0.73 yes yes yes yes
044110.7+255511 ITG 34 10.78 0.05 10.35 0.05 9.92 0.06 9.22 0.05 6.48 0.05 0.74 -1.25 yes yes yes yes
044112.6+254635 IRAS04381+2540 9.15 0.05 7.76 0.05 6.72 0.05 5.75 0.05 1.43 0.04 -1.92 0.22 -4.33 0.34 yes yes yes yes yes
044138.8+255626 IRAS04385+2550 8.24 0.05 7.74 0.05 7.13 0.05 6.05 0.05 1.86 0.04 -0.90 0.22 -2.73 0.22 yes yes yes yes yes
044148.2+253430 J04414825+2534304 11.43 0.05 10.93 0.05 10.50 0.06 9.54 0.05 6.33 0.05 1.02 -4.57 yes yes–faint yes yes
044205.4+252256 LkHa332/G2 AB 7.99 0.05 7.87 0.05 7.74 0.05 7.70 0.05 7.18 0.05 -4.69 yes yes no no b
044207.3+252303 LkHa332/G1 AB 7.65 0.05 7.62 0.05 7.53 0.05 7.51 0.06 0.51 -2.34 no no b
044207.7+252311 V955 Tau Ab 6.99 0.05 6.58 0.05 6.15 0.05 5.40 0.05 2.76 0.04 -0.56 0.22 -2.07 yes yes yes yes yes b
044221.0+252034 CIDA-7 9.51 0.05 9.11 0.05 8.65 0.05 7.79 0.05 4.20 0.04 1.13 0.22 -1.18 yes yes yes yes yes
044237.6+251537 DP Tau 7.57 0.05 6.90 0.05 6.34 0.05 5.37 0.05 1.90 0.04 0.54 0.22 -1.70 yes yes yes yes yes
044303.0+252018 GO Tau 8.90 0.05 8.64 0.05 8.21 0.05 7.42 0.05 4.30 0.04 1.03 0.22 0.53 yes yes yes yes yes
044427.1+251216 IRAS04414+2506 9.56 0.05 9.00 0.05 8.36 0.05 7.43 0.05 4.25 0.04 1.76