A mid-infrared imaging catalogue of post-AGB stars

A mid-infrared imaging catalogue of post-AGB stars1

Abstract

Post-AGB stars are key objects for the study of the dramatic morphological changes of low- to intermediate-mass stars on their evolution from the Asymptotic Giant Branch (AGB) towards the Planetary Nebula stage. There is growing evidences that binary interaction processes may very well have a determining role in the shaping process of many objects, but so far direct evidence is still weak. We aim at a systematic study of the dust distribution around a large sample of Post-AGB stars as a probe of the symmetry breaking in the nebulae around these systems. We used imaging in the mid-infrared to study the inner part of these evolved stars to probe direct emission from dusty structures in the core of Post-AGB stars in order to better understand their shaping mechanisms. We imaged a sample of 93 evolved stars and nebulae in the mid-infrared using VISIR/VLT, T-Recs/Gemini South and Michelle/Gemini North. We found that all the the Proto-Planetary Nebulae we resolved show a clear departure from spherical symmetry. 59 out of the 93 observed targets appear to be non resolved. The resolved targets can be divided in two categories. The nebulae with a dense central core, that are either bipolar and multipolar. The nebulae with no central core have an elliptical morphology. The dense central torus observed likely host binary systems which triggered fast outflows that shaped the nebulae.

keywords:
circumstellar matter – infrared: stars.
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1 Introduction

According to our current understanding of stellar evolution, all stars with main sequence mass in the range 1-8 M   evolve via the asymptotic giant branch (AGB) phase to the planetary nebula stage (PN). As they ascend the AGB, their mass-loss rate increases from solar-like values ( M/yr) up to M/yr. This mass loss is an essential component of galactic evolution, as these are the main sources of s-process elements in the Universe (Gustafsson & Ryde, 1996) and are the main productors of carbon. AGB stars are also the main contributors to the dust phase of the Interstellar Medium, which is important for the energy balance in Galaxies. During the last stages of the AGB, the remains of the convective hydrogen envelope are ejected during final violent and sporadic mass-loss events. Dust grains and molecules, predominantly CO, condense in their winds, forming substantial circumstellar envelopes detectable in the infrared and millimetric domains.

A departure from spherically symmetric mass-loss is observed in a substantial fraction of suspected transition objects. In particular, multipolar structures are often associated with Proto-Planetary Nebulae (PPNe) sources (Sahai, 2002). The observed morphology of these objects are projected on the sky, making it difficult to know what is the intrinsic morphology of PPNe and PNe. But it is estimated that around 80% of all PNe show aspherical morphologies (e.g. Manchado 1997). Hubble Space Telescope observations of PNe, for example, shows a large range of morphologies, including elliptical, bipolar, multipolar or round nebulae (e.g. Sahai & Trauger, 1998). Hydrodynamical models explain many of the observed structures from a structure-magnification mechanism, where a fast wind from the central star of the PN ploughs into the earlier slow Asymptotic Giant Branch (AGB) wind (Kwok et al. 1978), amplifying any density asymmetry already present (Balick, Preston & Icke 1987; Frank & Mellema 1994): the Generalized Interacting Stellar Wind model or GISW. Another model has also been proposed by Sahai & Trauger (1998) to explain the shaping of PNe. In their model the shaping of the PNe occurs at the end of the AGB phase when fast collimated jets are triggered and shape a bipolar nebula. If the direction of the jets changes with time, then multipolar nebulae can be formed. Such jets could be formed through interaction with a companion, e.g. in an accretion disc (for a review see Balick & Franck, 2002).

Much of PN and PPN shaping theory relies on the presence of circumstellar material in either a dusty torus or disc. Our team has discovered some discs/tori in the heart of PNe (Lagadec et al. 2006, Chesneau et al. 2006, Matsuura et al. 2006, Chesneau et al. 2007) using adaptive optics on the Very Large Telescope (VLT) and mid-infrared interferometry at the Very Large Telescope Interferometer (VLTI). But the role of these discs/tori for the shaping of the nebula is still unclear as we do not know which fraction of the total dusty mass is present in these central cores, nor the fraction of objects exhibiting such a disc/torus.

These equatorial structures are likely due to the interaction of the central star with a binary companion. But observation wise, there are yet no strong direct observational evidences for this neither in the PPN phase (Hrivnak et al.,2010). Miszalski et al.(2009, 2010) discovered some central binary systems in PNe, but no clear connection between the binaries and morphological class. Some binary post-AGB stars are known and they have very compact discs, not resolveable with direct imaging but only with interferrometry. These discs are lickely Keplerian and the binary orbits revealed so far indicate that strong interaction must have taken place on the AGB or even RGB. The Spectral Energy Distributions (SEDs) of these objects are specific and RV Tauri stars with dust are mainly found in this category (see e.g. Deroo et al.,(2006) for the interferometry; De Ruyter et al., (2006) for the SED; Van Winckel et al., (2009) for the binarity; De Ruyter et al., (2005) and Gielen et al. 2009 for the RV Tauri stars).

To observe the inner part of post-AGB stars, we need mid-infrared observations, as the dust optical depth is smaller at longer wavelengths. Mid-infrared is indeed the only wavelengths range at which we can observe the inner morphology of stars from the AGB to the PPN phase. Furthermore, the main source of radiation for these sources in the mid-infrared is direct emission from dust, while at shorter wavelengths this is scattered light. Mid-infrared imaging is thus the best way to study the dusty structures inside these evolved stars.

Many mid-infrared imaging observations of AGB and PPNe have been made in the past. But the only mid-infrared imaging survey has been made with 3-m class telescopes (Meixner et al. 1999) and present a lack of angular resolution for the morphological study of the observed objects, a selection bias as they observed known bipolar nebulae and consists of only 17 resolved sources. Some work has been done using 8-m class telescopes, but always focusing on particular individual bright well-known objects (e.g. Miyata et al. 2004).

We observed 86 evolved stars (2 observed twice, using different modes) using VISIR at the VLT, 5 using T-Recs (2 also observed with VISIR) on Gemini South and 5 using Michelle (1 also observed with VISIR) on Gemini North. Taking into account that some objects were observed twice with different instrument, our total list of targets includes 93 objects. Here we present this mid-infrared N-band imaging survey of a large number of post-AGB stars. We aim at a systematic survey to probe the inner dusty regions of post-AGB stars.

2 Target selection

The large sample of observations presented here comes from five distinct observing runs (3 VISIR/VLT runs:380.D-0630 (Normal mode), 081.D-0130 (Burst mode), 081.D-0616 (Normal mode); 1 Michelle/Gemini North: GN-2005B-Q-16 and 1 T-Recs/Gemini South run: GS-2005A-Q-34)) and the targets selection were done in a slightly different way for the different programs. The targets of the VISIR normal mode programs were selected from the previous mid-infrared catalogue by Meixner et al. (1999) and the millimetre observations compiled by Bujarrabal et al. (2001). We removed the AGB stars and young PNe and observed all the stars observable with the Very Large Telescope (VLT).

Most of the stars observed in burst mode were selected from the Torun post-AGB stars catalogue (Szczerba et al. 2007), that list 326 known post-AGB stars. We selected all the post-AGB stars observable in July from the ESO Cerro Paranal observatory with an IRAS 12 m flux larger than 10 Jy (the burst mode works only for bright stars). These post-AGB stars includes PPNe, R CrB stars and RV Tauri stars. R CrB are hydrogen deficient post-AGB stars with known obscuration events (Clayton, 1996). RV Tauri are pulsating post-AGB stars, located in the high luminosity end of the Population II Cepheid instability strip (Wallerstein, 2002). These RV Tauri stars are likely to harbour compact dusty discs (Van Winckel et al., 2003).

In addition to that, we observed the brightest Water Fountains, and AGB stars observable during this period. Water fountains are oxygen-rich PPNe characterized by the presence of blue and red-shifted OH and HO masers (Likkel & Morris, 1988). The stars observed with Gemini were selected from their infrared spectral properties. We selected star with double chemistry (characterized by the presence of PAHs and crystalline silicates in their infrared spectra), the unidentified 21-micron features or hints of the presence of an equatorial dusty disc/torus.

We observed 93 targets: 52 PPNe, 10 Water Fountains, 11 AGB stars, 8 RV Tauri stars, 4 PNe, 4 Massive Evolved Stars, 2 R CrB stars, 1 Be and 1 HII regions.

3 Observations and data reduction

3.1 VISIR/VLT observations

Most of the observations presented here were obtained with the mid-infrared instrument VISIR on the VLT (Lagage et al., 2004). All the stars were observed with 3 filters: PAH1 (8.59m, half band width 0.42m ), SiC (11.85m, 2.34m) and NeII (12.81m, 0.21m). The PAH1 and NeII filters were chosen for their good sensitivities and their location at the blue and red edge of the mid-infrared N band. They also avoid the large opacities of the SiC or silicates features and provide information on the dust continuum for both oxygen and carbon-rich stars. The broad SiC filter was chosen to provide a general N band view. Images obtained with the SiC filter generally have a higher signal to noise ratio due to the better sensitivity of this broad band filter. As all our selected targets are bright, we used the minimum integration time of 30s for all the filters in all our observations.

We used the imager in normal and burst mode, using a pixel scale of 0.075 arcsec and a field of view of 19.2 19.2 arcsec. We used the standard chopping/nodding technique to remove the noise from the sky. With the burst mode, all the single chopping and nodding images are recorded, allowing the reconstruction of quality-enhanced images using shift and add techniques and lucky imaging.

We used the standard chopping/nodding technique to remove the background, with a perpendicular chop throw, a chopping frequency of 0.25 Hz and an amplitude of 8 arcsec. We shifted and added the images using a maximum of correlation algorithm, after removing the bad images, selected as the one for which the measured flux was smaller than the mean flux of all the images minus one sigma. The great observing conditions during our run (0.43 mm of water in the atmosphere) allowed us to obtain great quality diffraction-limited images.

The normal mode data were reduced using the VISIR ESO pipeline. The pipeline first detect the bad pixels, and clean them using an interpolation with neighbouring pixels. Nodding images are then created by averaging the images in the two positions of the chopper. The nodded images are then shifted and added to form the final combined image.

3.2 T-Recs/Gemini South observations

Images were obtained using T-Recs/Gemini South and filters centred at 11.3m (PAH, =0.61m) and 18.3m (Qa, =1.51m). The chop throw was set to 15 arcseconds.

The IRAF MIDIR data reduction package MIREDUCE command was used to combine the different nod images. The resulting registered images were averaged together using the IRAF MISTACK routine. The pixel scale of the obtained images is 0.09 arcseconds and the field of view of is 28.8”21.6”

3.3 Michelle/Gemini observations

The observations were made with the mid-infrared camera Michelle on the 8-m Gemini North telescope (Hawaii, USA) in queue mode in different nights spread between the 26th of August 2005 and the 8th of January 2006. We observed BD +30 3639, IRAS 21282+5050, OH 231.8 and the Red Rectangle with three N-band filters (centred at 7.9 (=0.7m) 8.8 (=0.9m), 9.7(=1.0m) and 11.6 m (=1.1m)) and the Qa filter (centred at 18.5 m, =1.9m). HD 56126 was observed with the same filters and the N-band 7.9m filter. The N and Q band observations were made at different dates due to the more stringent weather requirements at Q band. The standard chopping-nodding technique was used to remove the sky, with a chop throw of 15 arcsec. The spatial resolution measured from standard stars was typically 0.4 arcsec at 10m and 0.6 arcsec at 18.5m. The field of view was 3224” and the pixel scale 0.099”.

Michelle data files contains planes consisting of the difference for each chopped pair for each nod-set. Using the Gemini IRAF package, these difference images were combined to create a single frame.

We thus observed in a quasi uniform way 93 evolved stars in the mid-infrared. The names, coordinates, observing modes used and generally accepted type classification of all the stars are presented in Table 1. Table 2 presents photometric measurements from the stars from Two Microns All Sky Survey (2MASS) and the InfraRed Astronomical Satellite (IRAS).

3.4 Flux calibration, deconvolution and artefacts

The VISIR mid-infrared detector used for most of the observations suffers from striping and the appearance of ghosts for bright stars. The stripes are horizontal and repeated every 16 pixels, while the ghosts are distributed vertically every 16 columns. This produces artefacts that could bring confusion for the image morphology classification.

For all the targets, we observed standard stars just after or before the observations. These standards stars were selected to have a similar airmass to our targets. These observations were reduced in a similar way as the science targets. They were used as a measurement of the point-spread function (PSF) and for flux calibration purposes. The flux calibration was performed using standard aperture photometry methods, applied to the program and reference stars. All the resolved targets were deconvolved using a Richardson-Lucy algorithm and 30 iterations, depending on the quality of the images.

4 Results

4.1 Measurements

For each star and each filter observation, we estimated the ellipticity of the obtained image using an ellipse fitting procedure to all the signal larger than 3 times the standard deviation of the distribution. This gives us an orientation of the object, as well as its dimensions along its major axis and the axis perpendicular to this axis. To estimate whether the objects were resolved or not, we fitted a Gaussian to the observed radial profiles for the objects (on the non-deconvolved images) and their associated PSF standard for the different filters. Given the seeing stability due to the exceptionally good weather condition for the VISIR burst mode run, it is straightforward to estimate whether an object is extended or not for objects observed in burst mode. For objects observed in service mode, we estimated that the objects were extended when the object was 50% more extended than its associated PSF. For some dubious cases, where there were hints of an extension in a given direction, we also checked the literature for similar structures observed at different wavelengths.

4.2 Observed morphologies

We observed 93 objects, and according to our measurements, 59 are point sources. A brief description of the properties of the resolved targets is presented in Table 8. Among these extended targets, we resolved a wealth of different structures, such as resolved central cores, dark central lanes, detached shells, S-shaped outflows. The asymmetrical object (IRAS 124056219) was misclassified as a post-AGB star and is in fact an H II region (Suarez et al., 2009). One object (IRAS 181841302) appears square-shaped object and is also a misclassified post-AGB. It is a Be star (Tuthill & Lloyd, 2007).

If we consider only the PPNe from our sample, we end up with a sample of 52 detected objects. 29 of this objects are not resolved and 6 are marginally resolved. Among the 17 clearly resolved objects, we find 3 ellipticals, 10 bipolars and 4 multipolars.

All 11 AGB stars that we observed are unresolved, as well as the 8 RV Tau stars. This seems to indicate that no dust shell is present around these stars or at least no large and bright shells. Half of the 10 Water Fountains we observed are resolved. None of the resolved ones are spherical. We observed 4 bipolar Water Fountains, most of them with a dark equatorial lane, and one multipolar. For the RCrB stars, one (IRAS 143163920) appears unresolved, and the other (IRAS 191323336) appears to be an unresolved central source with a more or less spherical dust shell around (very weak).

The morphologies of the clearly resolved objects are summarized in Table 8.

5 Resolved objects

5.1 Proto Planetary Nebulae

Iras 061761036

This object, dubbed the Red Rectangle (AFGL 915, HD44179), has been well studied since its discovery by Cohen et al. (1975). It certainly harbours a binary system and exhibits a dual dust chemistry, with the presence of PAHs and crystalline silicates, as revealed by its ISO spectrum (Waters et al., 1998). CO observations reveal the presence of a Keplerian disc in the equatorial plane (Bujarrabal et al., 2005). Observations in the optical and the near infrared of the Red Rectangle reveal an X-shaped nebula, projection of a bicone (Osterbart et al. 1997, Mékarnia et al., 1998, Tuthill et al., 2002). HST images of the nebula reveal a very complex morphology, with a ladder-like structure inside the X-shaped nebula (Cohen et al., 2004). The central star is not seen in these images, as it is obscured by a dark lane, certainly due to a dusty disc. The rung of the ladder show a quasi-periodic spacing, indicating a periodic mass-loss from the central star.

Hora et al. (1996) observed the Red Rectangle in the mid-infrared with UKIRT. Their multiwavelengths images (between 8 and 20 m) show a bright core surrounded by a rectangular shaped nebula. Lagadec et al. (2004) obtained TIMMI/ESO 3.6m images of the Red Rectangle in the N band. The observations reveal an extended () rectangular-shaped nebula elongated along the North-East/South-West direction and symmetrical along this direction. The central core appears unresolved. The X-shape seen at shorter wavelengths is clearly seen at 8.4m and is less clear at longer wavelengths. The Red Rectangle was also imaged with the SUBARU telescope (Miyata et al. 2004). A similar morphology is revealed, and their 8.8m image reveals a similar morphology as the one observed in the near-infrared (Mékarnia et al., 1998). The N band emission is dominated by UIR emission, attributed to PAHs, while the central bicone seen at the shortest wavelengths is predominantly due to emission from hot dust and /or from stochastically heated nanoparticles (Gledhill et al., 2009).

Our Michelle images of the Red Rectangle at 7.9, 8.8, 11.6, 12.5 and 18.1m are displayed Fig.4. The images at 7.9, 8.8, 11.6 and 12.5m are quite similar and display the well-known rectangular shape of the Red Rectangle, with dimensions 3.35.9”. The X-shape is clearly seen in our deconvolved images up to 11.6 m. At 18.1m, the emission is dominated by an unresolved point source.

Iras 071341005

HD 56126 is a well studied post-AGB star exhibiting the unidentified 21-micron dust feature (Kwok et al., 1989). It is a carbon rich post-AGB star and its envelope has been already resolved in the mid-infrared with TIMMI2 on the ESO 3.6m telescope (Hony et al. 2003) and OSCIR on Gemini North (Kwok et al. 2002). They clearly detected the central star at 10.3m and marginally at 11.7 and 12.5m. They resolved a shell-like envelope of 5 arcsec in diameter, clearly elongated toward the south-west. The shell is not complete and shows an opening in the direction of its elongation.

The VISIR images of IRAS 07134 at 8.59, 11.85 and 12.81m are displayed Fig. 5. Our Michelle/Gemini Images of HD 56126 at 8.8, 11.6, 12.5 and 18.1m are displayed Fig.6. The images have a similar morphology and dimensions of 4.4 4.8” at all the observed wavelengths. The envelope has a roughly elliptical shell with a PA 25, that is wider at the North. The brightest part of the nebula is a U-shaped structure located in the inner part of this elliptic envelope. This U-shaped structure shows a decrease in emission in the North-West. The central star is clearly detected from 8.6 to 11.9m weakly at 12.8m and not at longer wavelengths. Its relative brightness clearly decreases with increasing wavelength. Our images are very similar to those obtained previously, but are certainly sharper. This is clear in our deconvolved images that show the presence of filamentary structures and holes that are very similar in the three filters. We thus clearly see a hole in emission 1.4 arcsec south of the central star, which could be due to a decrease in the dust density, or to the presence of a cold dusty blob.

Iras 073991435

OH 231.8+4.2 is a remarkable bipolar nebula with a central star (QX Pup) still on the AGB with probably an A0 main sequence companion (Sanchez Contreras et al. 2004). Its circumstellar envelope has already been imaged at 11.7 and 17.9 m using the Keck telescope (Jura et al. 2002), showing it to be elongated along the same direction as the bipolar outflows observed at shorter wavelengths with a PA 22and a full length 3”, the nebula being wider toward the north-east. Our Michelle images of OH 231.8 at 8.8, 9.7, 11.6 and 18.1 m are displayed Fig.7. The vertical stripe at the east of the image is a detector artefact, amplified in our deconvolved images. Some artefacts are also seen in the 8.8m image, seen as ”holes” north and south of the central source. The four images are extended along a P.A. 22. The dimension of the images are 4.16.1”, 2.64.3”, 4.36.7” and 5.49.9”6.7 at 8.8, 9.7, 11.6 and 18.1 m respectively. All the images show the presence of a bright unresolved core and a diffuse halo. This halo is larger toward the south-east, in contradiction with observations by Jura et al. (2002). This is however in agreement with previous N band observations of this object with TIMMI on the ESO 3.6m telescope (Lagadec, Ph.D. thesis, 2005).

The central core appears resolved at 9.7m (its FWHM is 0.6 arcsec while its PSF standard has a FWHM of 0.6 arcsec) and 18.5m (FWHM of 0.8 and 0.6 arcsec for the object and its PSF respectively). These are the wavelength of silicates stretching and bending modes.

Mid-infrared spectro-interferometric observations of OH 231.8+4.2 have resolved the central core (Matsuura et al. 2006). This core was over-resolved by the interferometer near the deep silicate absorption feature they observed around 9.7m. This indicates the presence of a large silicate dust structure in the equatorial plane of OH 231.8+4.2.

Iras 101975750

Roberts 22 is a well studied PPN with dual dust chemistry (Sahai et al., 1999). Its envelope has been resolved in the mid-infrared with TIMMI observation on the ESO 3.6m telescope (Lagadec et al. 2005). They obtained 8.39 and 11.65m images of this object. Both images show an envelope elongated in the direction North-East/South-West along a P.A.45.

Images of the envelopes have also been obtained at shorter wavelengths by the Hubble Space Telescope, hereinafter HST, (Sahai et al. 1999, Ueta et al., 2007) or using the adaptive optics on the VLT (Lagadec et al. 2007). These images revealed the presence of an S-shaped envelope, embedded in a larger bipolar envelope.

Our VISIR and T-Recs images (Fig. 8 and 9) clearly show the presence of a large scale S-shaped envelope. An asymmetric torus is resolved in the core of this envelope from 8 to 18 m. The torus is brighter along the equator, which is more or less perpendicular to the bipolar nebula. We obtained VISIR observations of Roberts 22 with the same filters as the present observations in November 2006. The orientation of the torus appears exactly the same as the one we present here. The observed S-shaped structure of the nebula is thus certainly not due to precession from this torus. Note that the orientation of the torus appears to be wavelength dependent, as indicated by the Gemini Q band image. This is a radiative transfer effect.

Iras 151035754

This is a candidate PN with HO maser emission (Suárez et al. 2009). The images presented Fig. 10 are the first ever of this object. We clearly resolved a bipolar nebula with a narrow waist, probably due to a dense equatorial dusty structure. The nebula is elongated along a North-East/West direction along a P.A.35. Some spurs are observed at the edges of the bipolar structure and are more prominent in the North-West lobe. This could be due to the presence of the high velocity jets inferred by the water masers.

Iras 154455449

This is a water fountain nebula (Deacon et al. (2007)). We obtained the first ever images of this source. We resolved a compact (1.5” 2.3”) bipolar structure (Fig. 11), with a dark equatorial waist, indicating the presence of a dense equatorial structure. This equatorial lane is perpendicular to the bipolar lobes that are elongated along a P.A.5. The edges of these lobes are terminated by spurs, which are probably the projection of a biconical structure on the plane of the sky.

Iras 155535230

This is is a poorly studied PPN. It was resolved using optical HST observations (Sahai et al., 2007; Siódmiak et al., 2008). Their observations revealed a small (2.5 ”1.1”) bipolar nebula, seen nearly edge-on, elongated along the East/West direction with a dense equatorial waist, similar to a hourglass. The lobes differ in shape and size, which is probably due to the fact that the East lobe is pointing in our direction. A small feature is observed in this lobe and could be a faint outflow or jet.

Fig. 12 present our VISIR images of this source. We resolved the nebula, with a point source in its core, and it appears to be elongated along the East/West direction.

Iras 162794757

This object is a PPN stars with both carbon (PAHs) and oxygen-rich (crystalline silicates ) material in its envelope. This envelope was well studied by Matsuura et al. (2004) using TIMMI2/ESO 3.6m telescope mid-infrared images. They resolved the envelope and classified it as bipolar. Our VISIR observations (Fig. 13) show that the envelope of IRAS 16279-4757 has a much more complex morphology. A large scale S-shaped structure is clearly seen in the two filters, with some large scale horn-like structures toward the North-West and the South-West. The central star is clearly seen in all images, surrounded by Airy rings. On the deconvolved images we can see that the dust is organized in filamentary structures with many holes representing underdensities in the dust distribution. The big hole seen on the deconvolved PAH1 just North of the central star is an artefact due to the detector.

Iras 163423814

IRAS 163423814 is the prototypical object of the water fountain class (Likkel & Morris, 1988). It has been observed by Verhoelst et al. (2009). They resolved a bipolar nebula, separated by a waist dark even in the mid-infrared. They find that this dark waist is mostly made of amorphous silicates and that its filling angle is fairly large and that this structure is thus not a disc. Our two observations show the same bipolar morphologies, one of our filters being the same as the one used by Verhoelst et al. (2009). But, due to the use of the burst mode on VISIR our deconvolved images (Fig. 14) are sharper than the ones obtained earlier.

Iras 165944656

The Water-Lily Nebula PPN has been observed in the mid-infrared (N and Q bands) with T-Recs on Gemini (Volk et al., 2006) and with TIMMI2 on the ESO 3.6m telescope (Garcia-Hernandez et al., 2006). A bright equatorial torus, seen nearly edge-on, is clearly resolved in their images. No sign of the point symmetry observed in the optical images is seen in the mid-infrared ones. The nebula has an overall elliptical shape and is elongated along the east-west direction (P.A. 80). Our mid-infrared images (Fig. 15) show a similar morphology, but the larger dynamic range allows us to see some more diffuse dust emission beyond the lobes.

Iras 171063046

Optical HST images of the PPN IRAS 171063046 (the spindle nebula) indicate the presence of a collimated outflow emerging from a visible disc, embedded in a lower density elliptical halo (Kwok et al., 2000). The pair of lobes are collinear, orientated along a P.A. of 128, and the disc is perpendicular to these lobes with a P.A.42. Our images (Fig. 16) reveal the presence of a dense central structure along a P.A.42.

Iras 171503224

The Cotton Candy nebula is a well studied bipolar PPN. It has been observed in the optical and in the near-infrared by the HST (Kwok et al., 1998, Su et al., 2003). The central star is visible in the near infrared images, but not in the optical where it is obscured by a dark lane. This dark lane separates two lobes that form an extended bipolar nebula along a P.A. 112. Near-infrared spectroscopic observations provide evidence for the presence of an expanding torus in the core of IRAS 17150 (Weintraub et al., 1998).

Our VISIR and T-Recs images of IRAS 17150 are displayed Fig. 17 and 18. The central star is not seen in our images between 8 and 20 m. These images reveal an unresolved central peak, located at the position of the dark lane observed at shorter wavelengths. The nebula is elongated along a P.A. 108, similar to the bipolar nebula observed in the optical. An elongation is also seen in a direction roughly perpendicular to this bipolar nebula, more clearly in the 8.59m deconvolved image.

Iras 173114924

IRAS 173114924 is a carbon-rich PPN (Hony et al. 2002). Its ISO spectrum reveals the presence of PAHs, SiC and a 30-micron feature usually associated to MgS in it envelope (Hony et al. 2002). The images we present here are the first ever obtained for this object. The images reveal a bipolar nebula seen edge-on with two bright lobes on both sides of the polar direction. This is the projection of an equatorial torus, aligned with the bipolar structure.

Iras 174412411

The Silkworm Nebula is a PPN with a multipolar envelope (Ueta et al., 2007). It has been imaged at high angular resolution with the HST (Ueta et al., 2007) in the optical and near-infrared, and with Gemini in the mid-infrared (Volk et al. 2007), who resolved a torus, tilted by 23with respect to the bipolar nebula observed in the optical. They raised the possibility that this torus is precessing at a rate of 1.yr that could lead to the precession of the outflows. This is supported by the possible S-shape of the nebula, which can be seen in the near-infrared, and guessed in the mid-infrared Gemini images. This S-shaped structure is clearly seen in our VISIR image (Fig. 20), more particularly in the 11.65m deconvolved image. Our images are also deeper and reveal the presence of cooler dust around this structure as it in the case of Roberts 22.

Iras 182761431

IRAS 182761431 is a star in the short transition phase between the OH/IR phase and the PN phase, as indicated by the the progressive disappearance of HO maser (Engels, 2002). Near infrared images obtained with adaptive optics on the Keck (Sanchez-Contreras et al., 2007) show that the envelope of IRAS 18276 displays a clear bipolar morphology (PA23) with two lobes separated by a dark waist. Some strong OH masers activity is observed in the dense equatorial region, approximately perpendicular to the bipolar lobes (Bains et al., 2003). Our images show a bipolar structure with a P.A.9, embedded in a larger dusty structure (more visible at 11.65m, as this filter is more sensitive).

Iras 184500148

W43A is a water fountain source (Imai et al., 2002). Water maser observations of this source revealed the presence of a collimated and precessing jet of molecular gas. The HO maser spots are concentrated in two clusters, one receding (north-east) and one approaching (south-west side) (Imai et al., 2002). The two clusters are separated by 0.65 arcsec. The jets have a position angle of 62.70.5. Our VISIR observations allowed us to resolved a compact (1.2”1.6”) bipolar dust shell in W43A, orientated along a P.A.62. The molecular jets have thus certainly shaped the dusty bipolar structure we resolved.

Iras 190162330

IRAS 190162320 is a PPN (Garcia-Lario et al., 1997). Our images of IRAS 190162330 are the first ever obtained for this object. They show a compact structure elongated along a P.A.25, embedded in a structure elongated along the East/West direction.

Iras 193742359

This PPN has been observed in the optical with the HST (Ueta et al. 2000) and in the near-infrared with UKIRT, in imaging and polarimetry (Gledhill, 2005). In the optical, IRAS 193742359 appears bipolar, with its central star partially visible and limb brightened bipolar lobes along a P.A.6. The near infrared polarimetric maps indicate scattering and emission from an optically thin axisymmetric dust shell. The nebula appears to be brighter in the North than in the South and two brightness peaks can be seen East and West of the central star.

Our observations (Fig. 24) show a more or less elliptical nebula along a P.A.11. The detached shell predicted from the polarimetric observations is clearly resolved, and we confirm that the nebula is brighter toward the North. An opening in the shell is actually observed toward the South, and this object looks very similar to IRAS 07134+1005.

Iras 193860155

IRAS 193860155 was observed in the near-infrared imaging polarimetric survey by Gledhill (2005). Its degree of polarization is low but there is some evidence for scattering. The core of the polarized intensity image is elongated along an approximately North/South direction, while the outer region has a North-East/South-West orientation. They suggest that this object has a bipolar morphology. Our images (Fig. 25) are the first to resolve this object in the mid-infrared. We can see that the nebula is elongated in the South-East/North-West direction, perpendicular to the extension observed in the near-infrared.

Iras 194542920

This object is not very well studied. The only study of its morphology was done in the near-infrared imaging polarimetric survey performed by Gledhill et al. (2001). Their observations show that this object is unresolved and unpolarized. Our VISIR images (Fig. 26) reveal the presence of a bipolar nebula, elongated along a direction roughly East/West, with a central structure elongated in a direction perpendicular to the bipolar nebula.

Iras 195001709

IRAS 195001709 is a carbon-rich PPN, with 21 microns and 30 microns features in its mid-infrared spectrum (Justtanont et al., 1996). It has been imaged in the mid-infrared with OSCIR/Gemini North (Clube & Gledhill, 2004). An extended circumstellar envelope is detected, and there are some indications that this envelope is elongated along the North-East/South-West direction. Using radiative transfer modelling, Clube & Gledhill (2004) estimated the inner and outer radius of a detached dust shell around this object. They obtained an inner radius of 0.4 arcsec, not resolved with their OSCIR observations.

Our observations (Fig. 27) show that the envelope around 19500 is extended and elongated along two preferential direction, North-East/South-West as mentioned by Clube & Gledhill (2004) but also East/West. A detached shell is clearly resolved at all three wavelengths, with an inner radius of 0.4 arcsec.

Iras 200432653

IRAS 200432653 has been resolved in the near-infrared (K band) by Gledhill (2005) using polarimetric measurements. The polarization map suggests that the object is bipolar. This is supported by the polarized flux image, which show an extension along a P.A.120, while the polarization vectors are almost perpendicular to that direction. Our VISIR observations show that this object is slightly resolved and show an extension along a P.A.114in all three filters, in a similar direction as the polarisation flux image.

5.2 Planetary Nebulae

Iras 145625406

Hen 2113 (He 1044) is a very young PN with a [WC] central star, and displays dual dust chemistry , with the presence of PAHs (carbon-rich) and crystalline silicates in it envelope (Waters et al., 1998). HST observations reveal a complex morphology for this very young PN (Sahai et al. (2000)), with the presence of a spherical halo, remnant of the AGB mass-loss. A bipolar structure is observed along a P.A. 136, with a globally elliptical morphology with other faint lobes, the brightest along a P.A. 55. A bright core is observed in this elliptical structure, showing the presence of two rings separated by a dark lane. This object was observed by Lagadec et al. (2006) in the near and mid-infrared. Their observation are limited to the bright core and show that rings are the projection of a diabolo-like dusty structure (Lagadec et al. 2006). The central star is visible at short wavelength, up to 5 m, but is not detected in the N band.

Our T-Recs mid-infrared images (Fig. 29) reveal a global structure similar to the one reported by Lagadec et al. (2006). But the better resolution of the present observations allow us to clearly resolve the brightest ring in N and Q band.

Iras 163334807

IRAS 163334807 is a HO PN (Suarez et al., 2009). We present here the first resolved image of its envelope. We resolved a compact nebula. The envelope appears point symmetric, with an unresolved central core defining a very narrow equatorial waist. The holes seen North and South of the central star (more clearly seen in the deconvolved image) could be artefacts due to the detector. The point-symmetry of this source is an indication that it has been shaped by precessing jets.

Iras 17047-5650

CPD-568032 is a young PN with a [WC] central star and is spectroscopically the twin of Hen 2-113. An edge-on disc in its core has been discovered by De Marco et al. (2002) through HST/STIS spectroscopy. A study combining HST imaging and MIDI/VLTI interferometry of CPD-56 revealed the complexity of this object (Chesneau et al., 2006). The HST image reveals the presence of several lobes, in a shape similar to the Starfish nebulae described by Sahai & Trauger (1998). The farthest structure is located 7 arcsec away from the central star. A well-defined lobe is observed along a P.A. 53. The mid-infrared environment of CPD-568032 is barely resolved with single dish VLT images obtained during the MIDI acquisition at 8.7m. It is elongated along a P.A. of 104and a dimension of 0.3 arcsec 0.4 arcsec. This orientation corresponds to none of the observed lobes but is similar to that of a bow shock observed next to the central star in the HST image. The interferometric measurements reveal the presence of a dusty disc, with an orientation along a P.A. 28, corresponding to none of the structures observed.

Our T-Recs images (Fig. 31) reveal a bipolar nebula with a bright central structure elongated along a P.A. 123and an overall bipolar structure almost perpendicular to this. This central structure seems to indicate the presence of a dusty disc in this direction, but puzzlingly, its orientation is almost perpendicular to the one inferred from the MIDI observations. Two bright structure are observed toward the North and South of this equatorial structures,a and are separated by density gaps. The shape of the Northern structure has the same orientation as the bow shock observed by the HST.

Iras 173473139

IRAS 173473139 is a young PN with water masers. Its circumstellar envelope has been resolved by Sahai et al. (2007), using HST optical and near-infrared observations. These reveal the presence of bipolar collimated outflows separated by a dark waist. The lobes are asymmetric in shape and size, the north-west lobe being larger and the morphologies of these lobes seem to indicate that the jets shaping the nebula are precessing. A faint spherical halo can be observed at shorter wavelengths, up to a radius of 2 arcsec. VLA observations (Tafoya et al., 2009) reveals that the ionized shell consists of 2 structures. An extended (1.5 arcsec) bipolar structure with P.A.-30, similar to the one observed by the HST. The other structure is a central compact structure (0.25 arcsec) elongated in a direction perpendicular to the bipolar structure, similar to the dark lane observed in the HST image. IRAS 17347 appears slightly extended in the mid-infrared images published by Meixner et al. (1999) Our VISIR observations clearly resolved the bipolar structure with an unresolved central core. The deconvolved images reveal that the nebula is not bipolar, but multipolar. This indicates that the nebula has been shaped by precessing jets.

Iras 193273024

BD+303639, is one of the best studied dual dust chemistry PN. It is a dense, young PN with a [WC9] central star. HST imaging has shown that this nebula has a remarkable elliptical “squared off” morphology (Harrington et al. 1997). Kinematic studies of this object indicate that its nebula is seen nearly pole-on, with the rotational symmetry axis at about P.A. 30-60in the plane of sky and an inclination of about 20(Bryce & Mellema 1999).

Our Michelle images of BD+303639 at 8.8, 9.7, 11.6 and 18.5m are displayed Fig.33. The morphology of these images is remarkably similar to the optical ones obtained by the HST, displaying an elliptical-rectangular shape. The images are very similar at the 4 observed wavelengths with dimension 6.88.0”. The elliptical ring appears to be very clumpy, what is best seen on the deconvolved images. Note that the clumpy structures are observed at similar location in different images and are thus not deconvolution artefacts. The north east of the ring appears to be the brightest, while the south-east is weaker, displaying a kind of hole. This ring structure is surrounded by a faint elliptical halo. Some filamentary structure are also observed inside the ring, with a decreasing intensity toward the location of the central star that is not detected in any of our MIR images.

Iras 212825050

This is a young carbon rich PN with a [WC 11] central star and is located at 2kpc (Shibata et al. 1989). Michelle images of IRAS 21282+5050 at 8.8, 9.7, 11.6 and 18.1m are displayed Fig.34. As already mentioned by Meixner et al. (1993) using MIR observations and the NASA 3m IRTF telescope, the structure of the nebula appears the same in all the images, with an elliptical nebula having a major axis at a P.A. 165and two peaks lying almost East/West. The dimension of this extended structure is 5.4” 3.6”. The central star is not detected in all our images. The two observed lobes can be interpreted as the projection of a dusty torus seen roughly edge on.

5.3 Evolved massive objects

Iras 102155916

AFGL 4106 is a post-red supergiant binary (Molster et al., 1999). Optical observations with the ESO/NTT telescope revealed the shape of the ionized region in its circumstellar envelope through the H line (van Loon et al. 1999). An arc, extending from roughly North-East to South-West clockwise is seen. The TIMMI/ESO mid-infrared images of AFGL 4106 show that the dust has an oval to box shaped distribution, with a bright unresolved peak centred on the central objects (Molster et al. 1999). The dust distribution shows some indications of clumpiness. The North-West part of the nebula is fainter compared to the rest and seems slightly more extended, while the H shows a clear anti-correlation with the MIR emission.

Our T-Recs images of AFGL 4106 (Fig. 35) show a similar overall morphology of the dust distribution as the one observed by Molster et al. (1999). But the higher angular resolution of our observations allows us to resolve structure inside the envelope of AFGL 4106. The arc seen in H is clearly resolved, but larger, extending from East to West clockwise. A smaller arc is clearly seen, extending from North to West anticlockwise. Many other clumps and under densities are clearly seen. The central parts of the nebula show a bright clump, extended in a direction perpendicular to the elliptical nebula. The arcs seen could form a spiral structure, similar to the pinwheel nebula observed around WR 104 (Tuthill et al., 2008). The pinwheel structure observed in WR 104 is due to dust formation triggered by the interaction of the wind from the mass-losing star and the orbiting companion. AFGL 4106 is known to be a binary system, and it is thus very likely that the spiral structure we observe is also due to a wind-binary companion interaction.

Iras 171633907

IRAS 171633907 (Hen 1379) was discovered by Henize in 1976 (Henize et al., 1976). Despite being one of the brightest mid-infrared objects in the sky, it remains poorly studied. From near-infrared imaging, Epchtein et al. (1987) classified it as a PPN candidate. Its IRAS spectrum indicates the presence of silicate dust and it is unresolved in the optical by the HST (Siódmiak et al.), while speckle observations in the L band (3.6 m) indicate an angular dimension of 1.110.23 arcsec (Starck et al., 1994). We present here the first mid-infrared images of this target. It shows the presence of two concentric, almost circular, detached shells with a angular diameter of 5.5 arcsec. A point source is clearly seen in all the images, and is brighter at shorter wavelengths. The deconvolved images show that the overall spherical shells are made of smaller patchy structures.

Iras 191140002

IRAS 191140002 is classified as a yellow hypergiant or a post-AGB star, depending on the adopted distance. It was imaged in the mid-infrared with the Keck 1 telescope to resolve a detached shell around this object (Jura & Werber, 1999). This shell as an inner diameter of 3.3 arcsec and an outer diameter of at least 5.7 arcsec. They noted that the central star is offset from the centre of the shell by 0.35 arcsec. This central star appears asymmetric in the East-West direction. They explained this by imperfect chop/nod motion. They also noted that the northern part of the almost circular shell is brighter and present some departure from spherical symmetry. Gledhill & Takami (2001) modelled the dust shell around IRAS 19114 seen in their polarimetric observations (Gledhill et al. (2001)). They found that the observation are well reproduced with a spherically symmetric dust distribution and a r density law. This is an indication that during the mass-loss phase, the mass-loss rate was constant. They estimated the dust mass of the shell to be 0.08M. In our images we observe a similar detached shell at all wavelengths, but also an East/West extension in the central object at 8m. As the PSF observations associated with all our observations are perfectly circular and we used the same settings for these observations, this structure can not be due to chop/nod motion and is real. A weaker dusty structure seems to connect this central source to the detached shell. Some warmer dust is thus certainly present close to the central star.

Iras 192441115

IRC +10420 is a F red supergiant with a dusty circumstellar envelope. This star is certainly in the short transition phase between RSG and WolfRayet stars. It might be the only object in this transition phase (Blöcker 1999). It is one of the brightest source in N and Q band and has an intrinsic luminosity L5 10L for a distance estimated to 5kpc. IRC +10420 is thus very close to the HumphreysDavidson limit, upper limit to the luminosity of stars. HST observations (Humphreys et al., 1997) show that the nebula around IRC +10420 is extended ( 15 arcsec) with a bright core 3 arcsec in diameter. This core has a very complex morphology. It has been observed in N band (Humphreys et al. 1997; Meixner et al. 1999). These images in the mid infrared show that it contains two lobes separated by 1 arcsec. This core has a dimension 22 arcsec. HST observations show the presence of an elongation in the envelope with P.A. 215. Recent radial motion studies (Tiffany et al., 2010) indicate that we are viewing IRC +10420 nearly pole-on. The extension they observe toward the South-West is likely to be the equatorial plane, with the South-West side poiting toward us.

Our VISIR images reveals the presence of an extended envelope, with an extension toward the South-West along a P.A.223. It presents a more or less asymmetric morphology along that direction, as revealed by HST observations. The high dynamic range in our image also reveals the presence of complex structures inside the nebula.

5.4 Other objects

Iras 124056219

IRAS 124056219 has been classified as a possible PN, based on its IRAS colours (van de Steen & Pottasch, 1993). Suárez et al. (2009) noted that its near-infrared colours were very similar to those of H II regions. Our images show a morphology very unusual for a post-AGB star or a planetary nebula, but common to H II regions. IRAS 124056219 is thus very certainly an H II region.

Iras 181841302

MWC 922 (a.k.a. the Red Square nebula) is a dust enshrouded Be star (Tuthill & Lloyd, 2007). Near-infrared Palomar adaptive optics images reveals a regular and symmetric structure around that object (Tuthill & Lloyd, 2007). The images show a square-like structure, as the projection of biconal lobes, crossed by a series of rungs and an equatorial dark band crossing the core, with a P.A. of 46. Our mid-infrared images show the same square-like structure, even if it is not fully clear due to striping that affected the whole right part of all our images. Our deconvolved images clearly reveal the presence of a core with a similar orientation as the one assessed from near-infrared imaging.

6 Discussion

6.1 Two kinds of objects: resolved cores and detached shells

For the largest objects that are clearly resolved, we can notice that the PPNe observed can be divided into two categories: on one side the objects with a dense central core, in the form of a bright central source, resolved or not (IRAS 06176, IRAS 07399, IRAS 10197, IRAS 15103, IRAS 16279, IRAS 16594, IRAS 17150, IRAS 17311, IRAS 17441), or a dark lane, resolved or not, with most of the emission coming from the poles (IRAS 15445, IRAS 16342, IRAS 18276) indicating the presence of a large amount of dust, making the central regions optically thick even in the mid-infrared. On the other side, some objects do not have such a central core, and we can observe either a detached shell or the central star (IRAS 07134, IRAS 19374 and IRAS 19500). The objects without a central core all have an elliptical morphology, while the objects with a central core are either bipolar or multipolar. This can be seen in their Spectral Energy Distribution (SED), as the objects with a dense central core (Fig.1) or an equatorial dark lane (Fig.2) have a rather flat SED in the near-infrared wavelength range, due to the presence of hot dust close to the central star. The SED of the objects with detached shells are characterized by the presence of a clear double-peaked distribution (Fig.3), with a first peak shorter than 1 micron due to the central star, and a second peak due to the cool dust in the shell. The flux is much lower in the near-IR due to the absence of dust close to the central star.

The shape of the SED can be affected by the orientation of the nebula too. The orientation of the nebula affects the ratio between the photospheric and the dust peaks of the SED (Su et al., 2001), and only if the optic depth is significant. The presence/absence of infrared excess observed in our sources is different and thus not related to orientation effects. This infrared excess due to hot dust is an indication that the dense cores play a role in the shaping of the nebulae. Two main classes of models have been proposed to explain the shaping of nebulae. The first class of models is based on the Generalized Interacting Winds models described by Balick (1987). In these models, a fast wind from the central star of a PPN or PN interacts with a slower wind, remnant of the AGB phase, assumed to be toroidal.

In the second class of models, the primary shaping agents are high speed collimated outflows or jets that are created at the end of the AGB phase or at the beginning of the PPN phase (Sahai & Trauger, 1998). The interaction of these jets with a spherical AGB wind will create lobes that are in fact cavities. If the direction of the jets changes with time, multipolar nebulae can be shaped.

Both models require the presence of a central torus/disc in the core of the nebulae. Our observations clearly indicate that the bipolar and multipolar nebulae have such a central structure in their core.

Figure 1: Spectral Energy Distribution of the resolved objects with a bright central source
Figure 2: Spectral Energy Distribution of the resolved objects with an equatorial dark lane
Figure 3: Spectral Energy Distribution of the resolved objects with a detashed shell

6.2 Departure from circular symmetry

We resolved 25 PPNe in our survey. All these nebula show a clear departure from circular symmetry. Some circular shells are resolved in our survey, but only around massive evolved stars such as IRAS 17163 and IRAS 19114. A dramatic change in the the distribution of the circumstellar material is often observed when a star evolves from the AGB phase to the PN phase (Frank & Balick, 2002). Most AGB stars have a large scale cicularly symmetric morphology (Mauron & Huggin, 2006), while PNe display a variety of morphologies from elliptical to bipolar or multipolar. Parker et al. (2006), from a large optical imaging survey of PNe, found that 80% of the PNe show a clear sign of departure from circular symmetry, and thus that 20% of the PNe are spherical. The shaping of the PNe is thought to occur at the very end of the AGB phase or the beginning of the PPN phase. It is thus surprising that in our sample of 25 resolved PPN we do not find any circular ones.

The fact that we do not observe any circular PPNe could be a sample selection effect. We selected our targets as bright IRAS 12m sources. To be a bright emitter at these wavelengths, an object needs to have some dust hot enough (300K), and thus not far from the central star. This is the case for the stars with a central core, which are aspherical, as mentioned before. The spherical PPNe are fainter than the non spherical ones in the mid-infrared, due to the lack of central torus/disc emitting in this wavelength range. At the end of the AGB phase, the envelope of the AGB progenitors of circular PPNe are ejected and rapidly cool down while expanding. There are thus very few spherical PPNe that are bright in the mid-infrared. Furthermore those bright PPNe are compact and thus difficult to spatially resolve. The best way to detect such spherical envelopes is thus at longer wavelengths. Such detached shells are actually observed in the far infrared with the Herschel Space Observatory (Kerschbaum et al., 2010).

6.3 Formation of S-shaped structures

As we mentioned in Section 5.1.14, for IRAS 17441 a tilt is observed between the orientation of the central dusty torus we resolved and the tips of the observed S-shaped structure. Such a tilt was observed by Volk et al. (2007), and measured to be almost 90 degrees. They suggested that a precession of the dusty torus could explain the observed S-shaped structure of the nebula. They estimated the dynamical age of the envelope, assuming a distance of 1kpc and an expansion velocity of 100km/s, to be 100 yr. According to this, the torus should thus precess with a rate of 1/yr. As our observations were made 4 years after the observations presented by Volk et al. (2007), we should see a tilt of the torus of 4between the two observations. The images provided by these authors show that the orientation of the torus they observed is exactly the same as the one we observed. The torus in the core of IRAS 17441 is thus not precessing at such a high rate. When we compare the images we obtained of IRAS 17441 and IRAS 10197, one can see some very striking similarities. Both images reveal the presence of an S-shaped envelope with a resolved central dusty torus. The central torus of IRAS 10197 is also tilted with respect to the tips of the S-shaped structure, as noted by Ueta et al. (2007). These authors estimated the tilt to be 46. Some images of IRAS 10197 were obtained with VISIR in December 2005, two and a half years prior to our observations. We retrieved and reduced these data to analyse them. The orientation of the torus appears to be exactly the same as the one we observed. Assuming a distance to IRAS 10197 of 2kpc, an angular extension of the S-shaped structure of 2.5” and an expansion of 30km/s (Sahai et al., 1999), the dynamical age of this structure is 800 yr. The torus would thus need to precess with a rate of 0.06/yr to explain the S-shaped structure. Such a precession rate is almost impossible to detect with the observations we have.

It thus appears that we can not explain the observed S-shaped structures with a precession of the central tori. This could be due either to the fact that we underestimated the dynamical age of the nebula or that another mechanism is responsible for the S-shaped structure. A more plausible explanation is that the S-shaped structure is not due to the precession of the torus itself, but to precessing outflows inside this torus. The presence of such outflows has been observed in the PN NGC 6302 (Meaburn et al., 2008), which has a morphology very similar to those of IRAS 10197 and IRAS 17441. These outflows are Hubble-type, which means that their velocity is proportional to the distance from the source. A torus similar to the ones observed in the core of these objects is also seen in the core of NGC 6302 (Peretto et al., 2007). The properties of such outflows can be theoretically described by a sudden ejection of material, a ”bullet” as described by Dennis et al. (2008). Such bullets naturally account for mulitpolar flows, that could arise naturally from the fragmentation of an explosively driven polar directed shell. It is thus likely that the S-shaped observed in IRAS 17441 and IRAS 10197 is due to high speed outflows triggered at the end of the AGB phase or the beginning of the PPN phase, likely during an explosive event.

6.4 Chemistry and morphology

Amongst the PPNe and Water Fountains clearly resolved in our survey, 18 have a known dust chemistry: oxygen, carbon-rich or a dual dust chemistry with both carbonaceous and oxygeneous dust grains in their envelopes. For the oxygen-rich sources, we find that 10 out of 11 are bipolar or multipolar, while the remaining one is elliptical. For the carbon-rich sources, we find that 2 are bipolar or multipolar and 2 elliptical. The three objects with a dual dust chemistry are multipolar or bipolar. This is in agreement with the recent work by Guzman-Ramirez et al. (2010), which shows a strong correlation between dual dust chemistry and the presence of an equatorial overdensity. The dual dust chemistry could be due either to the formation of PAHs in an oxygen-rich torus after CO photodissociation, or to the presence of a long-lived O-rich disc formed before the star turned carbon-rich due to the third dredge-up.

In their mid-infrared catalogue, Meixner et al. (1999) used a different morphological classification and found that most of the elliptical source they resolved are O-rich , while the toroidal ones tend to be C-rich. Stanghellini et al. (2007) also studied the correlation between dust composition and morphologies. They determined, from a study of 41 Magellanic Clouds PNe, that all PNe with O-rich dust are bipolar or highly asymmetric. Our study agrees with this last finding, and it seems that O-rich PPNe appears to be bipolar or multipolar. As discussed by De Marco (2009), the low C/O ratio of these bipolar nebulae could be due to the interaction with a binary companion during a common envelope phase, or in the case of single star evolution, result from conversion of carbon to nitrogen. The common phase interaction will lead to the ejection of the envelope earlier than in the single star evolution scenario, leading to a less efficient dredge-up of carbon, and thus a lower C/O ratio (Izzard et al., 2006). The conversion of carbon to nitrogen occurs for massive AGB stars with the hot bottom burning process. It is thus likely that the bipolar PPNe have progenitor with larger masses than the ellitpical ones. This is in agreement with the work by Corradi & Schwartz (1995), who showed that bipolar PNe tend to have a higher progenitor mass. Soker (1998) proposed that this could be explained in the paradigm of binary system progenitors, as primaries that undergoes a common envelope phase, and thus become bipolar, tend to have a higher mass.

7 Conclusions

We imaged 93 evolved stars and nebulae in the mid-infrared using VISIR/VLT, T-Recs/Gemini South and Michelle/Gemini North. Our observed sample contains all the post-AGB stars observable from Paranal with an IRAS 12 m flux density larger than 10 Jy, including PPNe, RCrB, RV Tauri stars and Water Fountains. The sample also includes some 10 AGB stars, 4 PNe, 4 massive evolved stars, 1 H II region and a Be star.

These observations allowed us to resolve 34 objects, displaying a wealth of different structures, such as resolved central cores, dark central lanes, detached shells, S-shaped outflows. None of the AGB and RV Tauri stars appears to be resolved, indicating that no bright mid-infrared extended dust shells are present around these objects. Circular detached shells are resolved around 2 massive evolved stars.

We observed two kind of PPNe:

  • PPNe with a dense central core, in the form of a bright central source or a dark lane, resolved or not. All these objects are bipolar or multipolar and their SEDs display a near-infrared excess due to hot dust from a dense structure in the core of the object

  • PPNe with a detached shell or a visible central star. These objects are all elliptical and have a two peaked SED.

None of the PPNe appears to be circular, while a significant fraction of PNe, the evolutionary phase after the PPN phase, are known to be spherical. This is certainly a sample bias, as we selected bright mid-infrared stars. Spherical PPNe have no central torus/disc emitting in this wavelength range. At the end of the AGB phase, their envelope is ejected and rapidly cools down while expanding, and thus starts emitting at longer wavelengths and become brighter at longer wavelengths. Such detached shells are actually observed in the far infrared with the Herschel Space Observatory.

Precession of the central torii has been proposed to explain the S-shaped morphology of two of the objects we observed, IRAS 10197 and IRAS 17441. Using observations from different epochs, we do not see any sign of such a precession. We propose that the multipolar structures observed in the envelopes of these objects are due to outflows inside the torii, in a scenario similar to the one proposed by Sahai & Trauger (1998).

A large fraction of the dust in galaxies may be produced during the late stages of the evolution of low and intermediate mass stars. This dust is ejected to the ISM during the PPN phase. Our observations show the existence of two paths for this dust ejection, via a detached shell or an expanding torus. To better understand the importance of PPNe for the life cycle of dust, it would be interesting to study how the dust production by these objects is affected by these different paths. Spatially resolved mid-infrared spectra of these sources will allow us to study the dust composition at different locations in these PPNe and thus to better understand the dust evolution during the PPNe phase.

Acknowledgements

E.L thanks the ESO staff in Paranal, who helped making these observations successful. M.M. acknowledges an Origin Fellowship. R.Sz. acknowledge support from grant N203 511838 from Polish MNiSW. Fits and postcript images of the nebula will be made available publically via the Torun post-AGB catalogue database at http://www.ncac.torun.pl/postagb2

Appendix A Tables

IRAS name RA Dec Date. Telescope, Instrument () properties

IRAS 002450652
00 27 06.4 06 36 16.9 01 Jul 08, VLT, B 8.59 (0.42) AGB
01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 004774900 00 50 02.5 48 43 47.0 01 Jul 08, VLT, B 8.59 (0.42) AGB
01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 01037+1219 01 06 26.0 +12 35 53.0 29 Jun 08, VLT, B 8.59 (0.42) AGB
(CIT 3) 29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 012463248 01 26 58.1 32 32 35.5 29 Jun 08, VLT, B 8.59 (0.42) AGB
(R Scl) 29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 01438+1850 01 46 35.3 +19 05 03.7 01 Jul 08, VLT, B 8.59 (0.42) AGB
01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 022702619 02 29 15.3 26 05 55.7 29 Jun 10, VLT, B 8.59 (0.42) AGB
(R For) 29 Jun 10, VLT, B 11.85 (2.34)
29 Jun 10, VLT, B 12.81 (0.21)

IRAS 05113+1347
05 14 07.8 +13 50 28.3 09 Oct 07, VLT, N 8.59 (0.42) PPN
(GLMP 88) 09 Oct 07, VLT, N 11.85 (2.34)
09 Oct 07, VLT, N 12.81 (0.21)
IRAS 05341+0852 05 36 55.1 +08 54 08.7 17 Nov 07, VLT, N 8.59 (0.42) PPN
17 Nov 07, VLT, N 11.85 (2.34)
17 Nov 07, VLT, N 12.81 (0.21)
IRAS 061761036 06 19 58.2 -10 38 14.7 27 Dec 05, GN, M 7.90 (0.42) PPN
(Red Rectangle) 27 Dec 05, GN, M 8.80 (2.34)
27 Dec 05, GN, M 11.60 (0.21)
27 Dec 05, GN, M 12.50 (0.21)
27 Dec 05, GN, M 18.10 (0.21)
IRAS 065300213 06 55 31.8 02 17 28.3 17 Nov 07, VLT, N 8.59 (0.42) PPN
17 Nov 07, VLT, N 11.85 (2.34)
17 Nov 07, VLT, N 12.81 (0.21)
IRAS 07134+1005 07 16 10.3 +09 59 48.0 11 Dec 07, VLT, N 8.59 (0.42) PPN
11 Dec 07, VLT, N 11.85 (2.34)
11 Dec 07, VLT, N 12.81 (0.21)
19 Dec 05, GN, M 8.80 (0.42) PPN
19 Dec 05, GN, M 11.60 (2.34)
19 Dec 05, GN, M 12.50 (0.21)
19 Dec 05, GN, M 18.10 (0.21)
IRAS 072840940 07 30 47.5 09 46 36.8 14 Feb 08, VLT, N 8.59 (0.42) RV Tau
(RAFGL 1135) 14 Feb 08, VLT, N 11.85 (2.34)
14 Feb 08, VLT, N 12.81 (0.21)
IRAS 07331+0021 07 35 41.2 +00 14 58.0 11 Mar 08, VLT, N 8.59 (0.42) PPN
11 Mar 08, VLT, N 11.85 (2.34)
11 Mar 08, VLT, N 12.81 (0.21)
IRAS 073991435 07 42 16.8 -14 42 52.1 08 Jan 06, GN, M 8.80 (0.42) PPN
(OH 231.8 +4.2) 08 Jan 06, GN, M 9.70 (2.34)
08 Jan 06, GN, M 11.60 (0.21)
08 Jan 06, GN, M 18.10 (0.21)

IRAS 07430+1115
07 45 51.4 +11 08 19.6 15 Mar 08, VLT, N 8.59 (0.42) PPN
15 Mar 08, VLT, N 11.85 (2.34)
15 Mar 08, VLT, N 12.81 (0.21)
IRAS 080052356 08 02 40.7 24 04 42.7 23 Dec 07, VLT, N 8.59 (0.42) PPN
23 Dec 07, VLT, N 11.85 (2.34)
23 Dec 07, VLT, N 12.81 (0.21)
IRAS 101975750 10 21 33.8 58 05 48.3 21 Mar 08, VLT, N 8.59 (0.42) PPN
(Roberts 22) 21 Mar 08, VLT, N 11.85 (2.34)
21 Mar 08, VLT, N 12.81 (0.21)
07 Apr 04, GS, T 11.30 (0.42) PPN
07 Apr 04, GS, T 18.30 (2.34)


Table 1: Log of the observation, with the object Right Ascension, Declination, Date of the observations, telescope used (VLT= Very Large Telescope, GN= Gemini North, GS= Gemini South), instrument used (B = VISIR burst mode, N= VISIR normal mode, M= Michelle, T=T-Recs), wavelength of the observations in microns, equivalent width of the filter used in microns, and properties of the object (PPN= Proto-Planetary Nebula, WF = Water Fountain, MES= Massive Evolved Star, RV Tau = RV Tauri star, PN=Planetary Nebula)
IRAS name RA Dec Date. Telescope, Instrument () properties
IRAS 102155916 10 23 19.5 59 32 04.8 18 Apr 05, GS, T 11.30 (0.42) MES
(AFGL 4106) 18 Apr 05, GS, T 18.30 (2.34)
IRAS 113855517 11 40 58.8 55 34 25.8 21 Mar 08, VLT, N 8.59 (0.42) PPN
21 Mar 08, VLT, N 11.85 (2.34)
21 Mar 08, VLT, N 12.81 (0.21)
IRAS 114720800 11 49 48.0 08 17 20.4 19 Feb 08, VLT, N 8.59 (0.42) PPN
19 Feb 08, VLT, N 11.85 (2.34)
19 Feb 08, VLT, N 12.81 (0.21)
IRAS 122224652 12 24 53.5 47 09 07.5 30 Jun 08, VLT, B 8.59 (0.42) RV Tau
(CD46 7908 ) 30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 124056219 12 43 32.1 62 36 13.0 30 Jun 08, VLT, B 8.59 (0.42) HII
30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 125844837 13 01 17.8 48 53 18.7 30 Jun 08, VLT, B 8.59 (0.42) PPN
(V1028 Cen) 30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 134622807 13 49 02.0 28 22 03.5 01 Jul 08, VLT, B 8.59 (0.42) AGB
(WHya) 01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 143163920 14 34 49.4 39 33 19.8 30 Jun 08, VLT, B 8.59 (0.42) R CrB
(V854 Cen) 30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 144294539 14 46 13.7 45 52 07.8 30 Jun 08, VLT, B 8.59 (0.42) PPN
30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 145625406 14 59 53.5 54 18 07.5 09 May 04, GS, T 11.30 (0.42) PN
(Hen 2-113) 09 May 04, GS, T 18.30 (2.34)
IRAS 151035754 15 14 18.9 58 05 20.0 29 Jun 08, VLT, B 8.59 (0.42) WF
(GLMP 405) 29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 153735308 15 41 07.4 53 18 15.0 30 Jun 08, VLT, B 8.59 (0.42) PPN
30 Jun 08, VLT, B 11.85 (2.34)
IRAS 154455449 15 48 23.5 54 58 33.0 01 Jul 08, VLT, B 11.85 (2.34) WF
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 154525459 15 49 11.5 55 08 52.0 29 Jun 08, VLT, B 8.59 (0.42) PPN
IRAS 154695311 15 50 43.8 53 20 43.3 01 Jul 08, VLT, B 8.59 (0.42) RV Tau
01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 155535230 15 59 11.4 52 38 41.0 29 Jun 08, VLT, B 11.85 (2.34) PPN
(GLMP 440) 29 Jun 08, VLT, B 12.81 (0.21)
IRAS 162391218 16 26 43.7 12 25 35.8 01 Jul 08, VLT, B 8.59 (0.42) AGB
(VOph) 01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 162794757 16 31 38.1 48 04 04.0 29 Jun 08, VLT, B 8.59 (0.42) PPN
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 163334807 16 37 06.1 48 13 42.0 29 Jun 08, VLT, B 8.59 (0.42) WF
29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 163423814 16 37 40.1 38 20 17.0 29 Jun 08, VLT, B 11.85 (2.34) WF
(Water foutain nebula) 29 Jun 08, VLT, B 12.81 (0.21)
IRAS 165592957 16 59 08.2 30 01 40.3 15 Apr 08, VLT, N 8.59 (0.42) PPN
15 Apr 08, VLT, N 11.85 (2.34)
15 Apr 08, VLT, N 12.81 (0.21)
IRAS 165944656 17 03 10.0 47 00 27.0 01 Jul 08, VLT, B 8.59 (0.42) PPN
(Water Lily nebula) 01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 170281004 17 05 37.9 10 08 34.6 18 Apr 08, VLT, N 8.59 (0.42) PPN
(M29) 18 Apr 08, VLT, N 11.85 (2.34)
18 Apr 08, VLT, N 12.81 (0.21)
IRAS 170475650 17 09 00.9 56 54 47.9 07 Jul 05, GS, T 11.30 (0.42) PN
CPD-568032 07 Jul 05, GS, T 18.30 (2.34)
IRAS 170884221 17 12 22.6 42 25 13.0 18 Apr 08, VLT, N 8.59 (0.42) PPN
(GLMP 520) 18 Apr 08, VLT, N 11.85 (2.34)
18 Apr 08, VLT, N 12.81 (0.21)

IRAS name RA Dec Date. Telescope, Instrument () properties
IRAS 171063046 17 13 51.8 30 49 40.7 18 Apr 08, VLT, N 11.85 (2.34) PPN
18 Apr 08, VLT, N 12.81 (0.21)
IRAS 171503224 17 18 19.9 32 27 21.6 15 Apr 08, VLT, N 8.59 (0.42) PPN
(Cotton candy nebula) 15 Apr 08, VLT, N 11.85 (2.34)
15 Apr 08, VLT, N 12.81 (0.21)
09 Apr 04, GS, T 11.30 (0.42) PPN
09 Apr 04, GS, T 18.30 (2.34)
IRAS 171633907 17 19 49.3 39 10 37.9 29 Jun 08, VLT, B 8.59 (0.42) MES
Hen 31379 29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 172334330 17 26 58.6 43 33 13.6 30 Jun 08, VLT, B 11.85 (2.34) RV Tau
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 172434348 17 27 53.6 43 50 46.3 01 Jul 08, VLT, B 8.59 (0.42) RV Tau
(LR Sco) 01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 172453951 17 28 04.7 39 53 44.3 21 May 08, VLT, N 11.85 (2.34) PPN
(Walnut Nebula) 21 May 08, VLT, N 12.81 (0.21)
IRAS 173114924 17 35 02.5 49 26 26.3 30 Jun 08, VLT, B 8.59 (0.42) PPN
(LSE 76) 30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 173473139 17 38 01.3 31 40 58.0 26 May 08, VLT, N 8.59 (0.42) PPN
(GLMP 591) 26 May 08, VLT, N 11.85 (2.34)
26 May 08, VLT, N 12.81 (0.21)
IRAS 174412411 17 47 08.3 24 12 59.9 01 Jul 08, VLT, B 8.59 (0.42) PPN
(Silkworm nebula) 01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
31 May 08, VLT, N 8.59 (0.42) PPN
31 May 08, VLT, N 11.85 (2.34)
31 May 08, VLT, N 12.81 (0.21)
IRAS 175162525 17 54 43.5 25 26 27.0 30 Jun 08, VLT, B 8.59 (0.42) PPN
30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 175303348 17 56 18.5 33 48 43.3 30 Jun 08, VLT, B 8.59 (0.42) RV Tau
(Al Sco) 30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 17534+2603 17 55 25.2 +26 03 59.9 21 May 08, VLT, N 8.59 (0.42) PPN
21 May 08, VLT, N 11.85 (2.34)
21 May 08, VLT, N 12.81 (0.21)
IRAS 180432116 18 07 21.2 21 16 14.0 29 Jun 08, VLT, B 12.81 (0.21) WF
IRAS 180711727 18 10 06.1 17 26 34.5 21 Jun 08, VLT, N 8.59 (0.42) PPN
21 Jun 08, VLT, N 11.85 (2.34)
21 Jun 08, VLT, N 12.81 (0.21)
IRAS 18095+2704 18 11 30.7 +27 05 15.5 22 May 08, VLT, N 8.59 (0.42) PPN
22 May 08, VLT, N 11.85 (2.34)
22 May 08, VLT, N 12.81 (0.21)
IRAS 18123+0511 18 14 49.4 +05 12 56.0 29 Jun 08, VLT, B 8.59 (0.42) RV Tau
29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 181351456 18 16 25.6 14 55 15.0 29 Jun 08, VLT, B 8.59 (0.42) PPN
29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
OH 12.80.9 18 16 49.2 18 15 01.8 29 Jun 08, VLT, B 8.59 (0.42) WF
29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 181841302 18 21 15.9 13 01 27.0 21 May 08, VLT, N 8.59 (0.42) Be
(MWC 922) 21 May 08, VLT, N 11.85 (2.34)
21 May 08, VLT, N 12.81 (0.21)
IRAS 181841623 18 21 18.9 16 22 29.0 21 May 08, VLT, N 8.59 (0.42) PPN
21 May 08, VLT, N 11.85 (2.34)
IRAS 182761431 18 30 30.6 14 28 55.8 21 Jun 08, VLT, N 8.59 (0.42) PPN
(V* V445 Sct) 21 Jun 08, VLT, N 11.85 (2.34)
21 Jun 08, VLT, N 12.81 (0.21)
01 Jul 08, VLT, B 8.59 (0.42) PPN
01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)

IRAS name RA Dec Date. Telescope, Instrument () properties
IRAS 182860959 18 31 22.7 09 57 22.0 30 Jun 08, VLT, B 8.59 (0.42) WF
30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 184500148 18 47 40.8 01 44 57.0 01 Jul 08, VLT, B 11.85 (2.34) WF
(W43A) 01 Jul 08, VLT, B 12.81 (0.21)

IRAS 184600151
18 48 42.8 01 48 40.0 01 Jul 08, VLT, B 8.59 (0.42) WF
01 Jul 08, VLT, B 11.85 (2.34)
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 190162330 19 04 43.5 23 26 08.8 30 Jun 08, VLT, B 8.59 (0.42) PPN
30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 19075+0921 19 09 57.1 +09 26 52.2 21 May 08, VLT, N 8.59 (0.42) PPN
21 May 08, VLT, N 11.85 (2.34)
21 May 08, VLT, N 12.81 (0.21)
IRAS 19114+0002 19 13 58.6 +00 07 31.9 25 Apr 08, VLT, N 8.59 (0.42) MES
(AFGL 2343) 25 Apr 08, VLT, N 11.85 (2.34)
25 Apr 08, VLT, N 12.81 (0.21)
IRAS 19125+0343 19 15 01.1 +03 48 42.7 29 Jun 08, VLT, B 8.59 (0.42) RV Tau
(BD+03 3950) 29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 191260708 19 15 23.4 07 02 49.9 29 Jun 08, VLT, B 8.59 (0.42) AGB
(W Aql) 29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 191323336 19 16 32.7 33 31 20.3 29 Jun 08, VLT, B 8.59 (0.42) R Cbr
(RY Sgr) 29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 19134+2131 19 15 35.2 +21 36 34.0 01 Jul 08, VLT, B 11.85 (2.34) WF
01 Jul 08, VLT, B 12.81 (0.21)
IRAS 191750807 19 20 18.0 08 02 10.6 30 Jun 08, VLT, B 8.59 (0.42) AGB
(V1420 Aql) 30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 19192+0922 19 21 36.5 +09 27 56.5 21 May 08, VLT, N 8.59 (0.42) PPN
21 May 08, VLT, N 11.85 (2.34)
21 May 08, VLT, N 12.81 (0.21)
IRAS 19244+1115 19 26 48.0 +11 21 16.7 21 May 08, VLT, N 8.59 (0.42) MES
(IRC +10420) 21 May 08, VLT, N 11.85 (2.34)
21 May 08, VLT, N 12.81 (0.21)
IRAS 19327+3024 19 34 45.2 +30 30 58.9 26 Aug 05, GN, M 8.80 (0.42) PN
(BD+303639) 26 Aug 05, GN, M 9.70 (2.34)
26 Aug 05, GN, M 11.60 (0.21)
26 Aug 05, GN, M 18.10 (0.21)
IRAS 19343+2926 19 36 18.9 +29 32 50.0 21 May 08, VLT, N 8.59 (0.42) PPN
(Min Footprint) 21 May 08, VLT, N 11.85 (2.34)
21 May 08, VLT, N 12.81 (0.21)
IRAS 19374+2359 19 39 35.5 +24 06 27.1 24 Jul 08, VLT, N 8.59 (0.42) PPN
24 Jul 08, VLT, N 11.85 (2.34)
24 Jul 08, VLT, N 12.81 (0.21)
IRAS 19386+0155 19 41 08.3 +02 02 31.3 26 May 08, VLT, N 8.59 (0.42) PPN
(V1648 Aql) 26 May 08, VLT, N 11.85 (2.34)
26 May 08, VLT, N 12.81 (0.21)
IRAS 19454+2920 19 47 24.8 +29 28 10.8 24 Jul 08, VLT, N 8.59 (0.42) PPN
24 Jul 08, VLT, N 11.85 (2.34)
24 Jul 08, VLT, N 12.81 (0.21)
IRAS 19477+2401 19 49 54.9 +24 08 53.3 19 Jul 08, VLT, N ?8.59 (0.42) PPN
(Cloverleaf Nebula) 19 Jul 08, VLT, N 11.85 (2.34)
19 Jul 08, VLT, N 12.81 (0.21)
IRAS 19480+2504 19 50 08.3 +25 12 00.9 17 Jul 08, VLT, N 8.59 (0.42) PPN
17 Jul 08, VLT, N 11.85 (2.34)
17 Jul 08, VLT, N 12.81 (0.21)
IRAS 195001709 19 52 52.7 17 01 50.3 25 Apr 08, VLT, N 8.59 (0.42) PPN
(V5112 Sgr) 25 Apr 08, VLT, N 11.85 (2.34)
25 Apr 08, VLT, N 12.81 (0.21)
IRAS 20004+2955 20 02 27.4 +30 04 25.5 21 May 08, VLT, N 8.59 (0.42) PPN
21 May 08, VLT, N 11.85 (2.34)
21 May 08, VLT, N 12.81 (0.21)

IRAS name RA Dec Date. Telescope, Instrument () properties
IRAS 20043+2653 20 06 22.7 +27 02 10.6 17 Jul 08, VLT, N 8.59 (0.42) PPN
(GLMP 972) 17 Jul 08, VLT, N 11.85 (2.34)
17 Jul 08, VLT, N 12.81 (0.21)
IRAS 200770625 20 10 27.9 06 16 13.6 25 Apr 08, VLT, N 8.59 (0.42) PPN
25 Apr 08, VLT, N 11.85 (2.34)
25 Apr 08, VLT, N 12.81 (0.21)
IRAS 20547+0247 20 57 16.4 +02 58 44.0 29 Jun 08, VLT, B ?8.59 (0.42) PPN
(U Equ) 29 Jun 08, VLT, B ?11.85 (2.34)
29 Jun 08, VLT, B ?12.81 (0.21)
IRAS 210320024 21 05 51.7 00 12 40.3 29 Jun 08, VLT, B 8.59 (0.42) AGB
(RV Aqr) 29 Jun 08, VLT, B 11.85 (2.34)
29 Jun 08, VLT, B 12.81 (0.21)
IRAS 21282+5050 21 29 58.4 +51 03 59.8 03 Sep 05, GN, M 8.80 (0.42) PPN
03 Sep 05, GN, M 9.70 (2.34)
03 Sep 05, GN, M 11.60 (0.21)
03 Sep 05, GN, M 18.10 (0.21)
IRAS 221964612 22 22 44.2 45 56 52.6 30 Jun 08, VLT, B 8.59 (0.42) AGB
(pi Gru) 30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B 12.81 (0.21)
IRAS 223271731 22 35 27.5 17 15 26.9 30 Jun 08, VLT, B 8.59 (0.42) PPN
(HM Aqr) 30 Jun 08, VLT, B 11.85 (2.34)
30 Jun 08, VLT, B ?12.81 (0.21)
IRAS 23166+1655 23 19 12.4 +17 11 35.4 16 Jul 08, VLT, N 8.59 (0.42) PPN
(RAFGL 3068) 16 Jul 08, VLT, N 11.85 (2.34)
16 Jul 08, VLT, N 12.81 (0.21)

IRAS name J H K F F F F MIR spectra












IRAS 002450652
1.581 0.621 0.236 1.16e+02 5.90e+01 1.15e+01 4.49e+00 1
IRAS 004774900 3.184 2.228 1.862 1.92e+01 1.01e+01 1.44e+00 1.14e+00 1
IRAS 01037+1219 7.437 4.641 2.217 1.16e+03 9.68e+02 2.15e+02 7.21e+01 1,2
IRAS 012463248 1.973 0.695 0.117 1.62e+02 8.21e+01 5.48e+01 2.32e+01 1,2
IRAS 01438+1850 2.016 1.012 0.722 7.67e+01 3.99e+01 6.60e+00 2.80e+00 1
IRAS 022702619 4.230 2.537 1.349 2.54e+02 7.53e+01 1.60e+01 5.06e+00 1,2
IRAS 05113+1347 9.020 8.423 8.171 3.78e+00 1.53e+01 5.53e+00 1.67e+00 1
IRAS 05341+0852 10.009 9.405 9.108 4.51e+00 9.85e+00 3.96e+00 8.01e+00 2
IRAS 061761036 6.577 5.145 3.655 4.21e+02 4.56e+02 1.73e+01 6.62e+01 1,2
IRAS 065300213 9.651 8.909 8.512 6.11e+00 2.74e+01 1.51e+01 4.10e+00
IRAS 07134+1005 6.868 6.708 6.606 2.45e+01 1.17e+02 5.01e+01 1.87e+01 1,2
IRAS 072840940 4.925 4.269 4.042 1.24e+02 8.84e+01 2.66e+01 9.54e+00 1
IRAS 07331+0021 5.816 5.322 4.940 1.53e+01 6.81e+01 1.85e+01 3.68e+00 1
IRAS 073991435 9.863 8.281 6.546 1.90e+01 2.26e+02 5.48e+02 2.94e+01 1,2
IRAS 07430+1115 8.836 8.211 7.766 7.68e+00 2.99e+01 1.07e+01 2.53e+00 1
IRAS 080052356 7.974 6.923 5.685 1.80e+01 5.18e+01 2.98e+01 1.04e+01 1
IRAS 101975750 9.877 8.966 7.399 2.00e+02 1.09e+03 5.88e+02 2.73e+02 1,2
IRAS 102155916 4.406 3.432 2.970 2.01e+02 1.76e+03 8.51e+02 1.81e+02 1,2
IRAS 113855517 5.947 5.138 3.991 9.26e+01 1.38e+02 1.93e+02 1.04e+02 1,2
IRAS 114720800 9.657 9.047 8.630 1.14e+01 1.42e+01 1.78e+00 1.00e+00 1
IRAS 122224652 6.941 6.380 5.338 3.25e+01 3.32e+01 7.99e+00 2.41e+00 1
IRAS 124056219 16.689 13.928 11.689 1.66e+01 1.09e+02 2.51e+02 4.30e+02 1
IRAS 125844837 10.177 9.424 7.805 3.61e+01 4.88e+01 1.30e+01 3.31e+00 1,2
IRAS 134622807 1.737 2.689 3.215 4.20e+03 1.19e+03 1.95e+02 7.22e+01 1,2
IRAS 143163920 6.106 5.695 4.875 2.30e+01 7.82e+00 1.51e+00 1.03e+00 1
IRAS 144294539 10.636 9.818 9.133 1.46e+01 3.33e+01 1.36e+01 2.91e+00 1
IRAS 145625406 9.821 8.934 7.531 9.24e+01 3.10e+02 1.77e+02 7.13e+01 1,2
IRAS 151035754 15.191 12.718 10.643 1.08e+01 1.02e+02 1.26e+02 1.03e+02 1
IRAS 153735308 15.037 11.664 8.756 3.80e+01 5.62e+01 4.25e+01 1.18e+02 1
IRAS 154455449 15.315 13.723 12.982 6.88e+00 8.72e+01 1.13e+03 2.18e+03
IRAS 154525459 11.034 8.837 6.973 8.71e+01 2.43e+02 2.74e+02 4.01e+02 1,2
IRAS 154695311 7.190 6.235 4.967 4.88e+01 4.21e+01 1.55e+01 2.78e+02 1
IRAS 155535230 13.380 11.534 9.859 9.99e+00 7.00e+01 4.96e+01 2.83e+02 1,2
IRAS 162391218 3.972 2.566 1.731 2.90e+01 8.35e+00 1.99e+00 1.66e+00 1
IRAS 162794757 8.660 6.605 5.490 4.30e+01 2.68e+02 1.63e+02 2.65e+02 1,2
IRAS 163334807 11.353 10.504 10.184 9.33e+00 4.30e+01 8.93e+01 1.13e+02 1
IRAS 163423814 11.608 10.589 9.569 1.62e+01 2.00e+02 2.90e+02 1.39e+02 1,2
IRAS 165592957 11.596 10.713 9.347 9.17e+00 3.24e+01 1.64e+01 4.18e+00 1
IRAS 165944656 9.881 9.002 8.260 4.49e+01 2.98e+02 1.31e+02 3.44e+01 1,2
IRAS 170281004 11.198 9.177 6.996 5.05e+01 1.10e+02 1.24e+02 7.58e+01 1
IRAS 170475650 9.513 8.499 6.862 1.43e+02 2.57e+02 1.99e+02 9.20e+01 1,2
IRAS 170884221 13.208 11.891 11.328 4.27e+01 1.28e+02 1.07e+02 3.69e+01 1
IRAS 171063046 9.975 8.906 8.316 4.01e+00 6.24e+01 5.12e+01 1.73e+01 1
IRAS 171503224 11.099 10.219 9.391 5.79e+01 3.22e+02 2.68e+02 8.24e+01 1,2
IRAS 171633907 4.635 3.021 2.407 1.24e+03 1.15e+03 6.63e+02 5.92e+02 1
IRAS 172334330 10.423 9.592 8.371 1.70e+01 1.34e+01 3.67e+00 3.21e+01 1
IRAS 172434348 8.035 7.358 6.462 1.08e+01 8.77e+00 3.69e+00 5.41e+00 1
IRAS 172453951 11.234 10.375 9.716 3.36e+00 4.47e+01 3.82e+01 9.77e+01 1
IRAS 173114924 9.793 9.543 9.203 1.83e+01 1.51e+02 5.87e+01 1.78e+01 1,2
IRAS 173473139 15.097 12.932 10.302 1.90e+01 1.00e+02 1.25e+02 2.49e+02 1
IRAS 174412411 11.088 10.132 9.380 4.28e+01 1.91e+02 1.06e+02 2.78e+01 1,2
IRAS 175162525 8.695 6.850 5.082 5.16e+01 1.16e+02 1.00e+02 2.92e+02 1,2
IRAS 175303348 6.864 6.179 5.485 1.76e+01 1.14e+01 2.95e+00 4.68e+01 1
IRAS 17534+2603 4.998 4.239 3.632 9.75e+01 5.45e+01 1.34e+01 6.04e+00 1,2
IRAS 180432116 14.546 13.404 13.042 6.60e+00 6.76e+00 1.66e+01 2.37e+02 1
IRAS 180711727 15.889 14.149 12.713 2.37e+01 7.66e+01 8.35e+01 3.05e+02 1
IRAS 18095+2704 7.366 6.728 6.438 4.51e+01 1.26e+02 2.78e+01 5.64e+00 1,2
IRAS 18123+0511 7.974 7.399 6.729 1.07e+01 1.10e+01 4.21e+00 1.85e+00 1
IRAS 181351456 15.417 13.751 13.130 3.10e+01 1.24e+02 1.58e+02 4.29e+02 1
OH 12.80.9 17.041 15.725 11.639 1.16e+01 1.69e+01 1.39e+01 2.89e+02
IRAS 181841302 8.960 7.396 5.704 3.36e+02 5.98e+02 2.53e+02 4.36e+02 1
IRAS 181841623 5.136 4.537 4.106 7.00e+01 3.25e+02 1.17e+02 5.84e+02 1
IRAS 182761431 11.670 10.810 9.450 2.26e+01 1.32e+02 1.20e+02 3.86e+01 1,2

Table 2: MIR spectra: 1: IRAS, 2: ISO
IRAS name J H K F F F F MIR spectra
IRAS 182860959 15.431 13.562 12.674 2.49e+01 2.45e+01 1.84e+01 4.05e+02 1
IRAS 184500148 16.115 14.794 13.219 2.37e+01 1.04e+02 2.95e+02 2.52e+03 1
IRAS 184600151 13.732 13.813 13.435 2.09e+01 3.27e+01 2.77e+02 2.91e+02
IRAS 190162330 12.500 11.343 9.966 1.26e+01 5.75e+01 2.80e+01 9.54e+00 1
IRAS 19075+0921 16.920 15.536 14.666 1.33e+02 1.64e+02 5.49e+01 7.80e+01
IRAS 19114+0002 5.371 4.998 4.728 3.13e+01 6.48e+02 5.16e+02 1.68e+02 1,2
IRAS 19125+0343 7.903 7.076 5.650 2.89e+01 2.65e+01 7.81e+00 2.80e+01 1
IRAS 191260708 1.534 0.238 0.556 1.58e+03 6.70e+02 1.12e+02 3.60e+01 1,2
IRAS 191323336 5.577 5.423 5.139 7.72e+01 2.62e+01 5.43e+00 4.60e+00 1,2
IRAS 19134+2131 16.543 14.926 13.464 5.06e+00 1.56e+01 8.56e+00 3.95e+00 1
IRAS 191750807 5.996 3.593 1.828 3.84e+02 1.93e+02 4.79e+01 1.56e+01 1
IRAS 19192+0922 9.449 6.759 4.821 1.27e+02 1.55e+02 4.14e+01 9.78e+00 1
IRAS 19244+1115 5.466 4.544 3.612 1.35e+03 2.31e+03 7.18e+02 1.86e+02 1
IRAS 19327+3024 9.306 9.231 8.108 8.93e+01 2.34e+02 1.62e+02 7.00e+01 1,2
IRAS 19343+2926 9.908 7.929 6.209 1.75e+01 5.98e+01 1.18e+02 6.80e+01 1,2
IRAS 19374+2359 12.038 10.866 9.735 2.36e+01 9.82e+01 7.09e+01 7.68e+02 1
IRAS 19386+0155 7.951 7.069 6.011 1.74e+01 4.74e+01 1.86e+01 3.79e+00 1,2
IRAS 19454+2920 11.853 10.749 10.426 1.73e+01 8.96e+01 5.44e+01 1.47e+01 1,2
IRAS 19477+2401 12.611 10.752 9.606 1.12e+01 5.49e+01 2.71e+01 3.80e+01 1,2
IRAS 19480+2504 15.216 14.036 13.559 2.08e+01 6.79e+01 4.32e+01 2.67e+01 1,2
IRAS 195001709 7.228 6.970 6.858 2.78e+01 1.65e+02 7.34e+01 1.82e+01 1,2
IRAS 20004+2955 4.766 4.305 3.793 3.17e+01 3.70e+01 4.66e+00 3.35e+01 1,2
IRAS 20043+2653 17.431 14.870 10.604 1.79e+01 4.20e+01 2.03e+01 7.48e+00 1
IRAS 200770625 6.906 3.923 2.059 1.26e+03 1.06e+03 2.16e+02 6.37e+01 1
IRAS 20547+0247 11.561 10.132 8.405 4.55e+01 3.38e+01 1.00e+01 2.84e+00 1
IRAS 210320024 4.046 2.355 1.239 3.08e+02 1.16e+02 2.24e+01 8.55e+00 1,2
IRAS 21282+5050 11.504 10.709 9.551 5.10e+01 7.44e+01 3.34e+01 1.50e+01 1,2
IRAS 221964612 0.715 1.882 2.351 9.08e+02 4.37e+02 7.73e+01 2.33e+01 1,2
IRAS 223271731 8.276 7.609 6.705 5.57e+00 4.66e+00 2.11e+00 1.01e+00 2
IRAS 23166+1655 17.165 15.402 10.379 1







Source PSF
F FWHM Size P.A. FWHM
IRAS name (m) (Jy) (arcsec) arcsecarcsec (arcsec) name

002450652
8.59 73.2 0.26 unresolved 0.24 HD 196321
11.85 82.5 0.33 unresolved 0.30
12.81 84.2 0.38 unresolved 0.32
004774900 8.59 15.9 0.31 unresolved 0.30 HD 196321
11.85 13.8 0.31 unresolved 0.30
12.81 12.0 0.32 unresolved 0.32
01037+1219 8.59 501.5 0.67 unresolved (saturated) 0.23 HD 198048
11.85 709.2 0.63 unresolved (saturated) 0.30
12.81 789.4 0.47 unresolved (saturated) 0.32
012463248 8.59 170.9 0.33 unresolved (saturated) 0.23 HD 198048
11.85 132.3 0.37 unresolved (saturated) 0.30
12.81 78.4 0.33 unresolved 0.33
01438+1850 8.59 56.0 0.72 unresolved (saturated) 0.43 HD 196321
11.85 63.8 0.52 unresolved (saturated) 0.30
12.81 53.9 0.33 unresolved 0.32

022702619
8.59 164.4 0.33 unresolved 0.30 HD 196321
11.85 131.5 0.37 unresolved 0.30
12.81 71.9 0.33 unresolved 0.32
05113+1347 8.59 0.8 0.52 unresolved 0.55 HD 31421
11.85 3.8 0.57 unresolved 0.49
12.81 4.1 0.51 unresolved 0.44
05341+0852 8.59 2.4 0.32 unresolved 0.26 HD 39400
11.85 5.0 0.34 unresolved 0.30
12.81 4.8 0.36 unresolved 0.33
061761036 7.90 365.7 0.31 3.35.9 0.22 HD 59381
8.80 313.1 0.31 3.35.9 0.22
11.60 375.7 0.36 3.35.9 0.26
12.50 408.9 0.34 3.35.9 0.28
18.10 251.9 0.47 3.35.9 0.38
065300213 8.59 1.4 0.35 unresolved 0.28 HD 49293
11.85 6.1 0.67 unresolved 0.13
12.81 1.5 0.05 unresolved 0.32
07134+1005 8.59 4.9 0.25 4.84.6 N/A 0.23 HD 58207
11.85 14.6 1.19 5.04.7 27 0.34
12.81 16.3 1.46 4.84.7 23 0.37


072840940
8.59 98.2 0.28 unresolved 0.30 HD 59381
11.85 126.7 0.33 unresolved 0.34
12.81 103.4 0.36 unresolved 0.33
07331+0021 8.59 6.5 0.30 unresolved 0.26 HD 61935
11.85 16.7 0.36 unresolved 0.35
12.81 17.5 0.40 unresolved 0.39
073991435 8.80 18.3 0.34 4.16.1 0.34 Alpha CMa
9.70 6.3 0.36 2.64.3 0.36
11.60 18.2 0.54 4.36.7 0.33
18.10 22.6 0.81 5.46.7 0.41
07430+1115 8.59 3.0 unresolved HD 62721
11.85 9.6 0.41 unresolved 0.32
12.81 9.7 0.42 unresolved 0.33
080052356 8.59 14.0 0.28 unresolved 0.27 HD 67523
11.85 16.7 0.34 unresolved 0.32
12.81 17.5 0.36 unresolved 0.33
101975750 8.59 97.1 0.74 4.43.2 44 0.25 HD 91942
11.85 181.6 0.75 4.93.6 42 0.31
12.81 215.4 0.75 4.73.5 42 0.34
102155916 11.30 216.1 0.72 3.43.3 N/A 0.42 Gamma Gru
18.30 1395.33 4.01 3.43.3 N/A 0.53
113855517 8.59 69.3 0.28 unresolved 0.25 HD 102461
11.85 86.6 0.31 unresolved 0.28
12.81 87.1 0.34 unresolved 0.33


Table 3: Observed fluxes and sizes of objects, position angle of the resolved nebula, and name of teh associated PSF standard
114720800 8.59 0.30 unresolved 0.30 HD 99167
11.85 7.1 0.33 unresolved 0.32
12.81 5.1 0.34 unresolved 0.36
122224652 8.59 23.2 0.23 unresolved 0.23 HD 111915
11.85 28.8 0.28 unresolved 0.29
12.81 24.4 0.33 unresolved 0.32
124056219 8.59 4.9 0.54 2.32.1 128 0.23 HD 111915
11.85 12.7 0.67 3.12.8 133 0.30
12.81 16.7 1.04 3.12.9 126 0.32


125844837
8.59 27.4 0.26 unresolved 0.23 HD 111915
11.85 28.6 0.30 unresolved 0.30
12.81 22.3 0.32 unresolved 0.32
1346228071 8.59 1075.4 0.99 2.32.0 43 0.27 HD 124294
11.85 1522.8 1.01 2.22.0 39 0.31
12.81 1527.8 0.76 1.91.8 45 0.33
143163920 8.59 19.1 0.24 unresolved 0.24 HD 111915
11.85 12.5 0.31 unresolved 0.30
12.81 11.6 0.33 unresolved 0.33
144294539 8.59 10.3 0.32 unresolved 0.24 HD 111915
11.85 14.6 0.36 unresolved 0.30
12.81 15.2 0.40 unresolved 0.33

145625406
11.30 87.1 1.39 6.04.6 92 0.39 Alpha Cen
18.30 246.4 1.62 5.64.4 82 0.55
151035754 8.59 1.0 0.34 1.81.3 32 0.25 HD 133550
11.85 5.6 0.52 2.52.3 32 0.31
12.81 13.8 0.53 3.02.0 32 0.33
153735308 8.59 31.3 0.24 unresolved 0.24 HD 133774
11.85 33.8 0.30 unresolved 0.30
154455449 11.85 3.2 0.32 3.62.9 -3 0.32 HD 124294
12.81 6.8 0.51 3.12.0 1 0.33
154525459 8.59 nodetection HD 133774

154695311
8.59 40.3 0.24 unresolved 0.26 HD 124294
11.85 40.3 0.25 unresolved 0.31
12.81 39.0 0.32 unresolved 0.33

155535230
11.85 0.52 3.73.6 91 0.30 HD 133774
12.81 0.45 3.43.2 83 0.33
162391218 8.59 30.7 0.25 unresolved 0.26 HD 124294
11.85 21.4 0.28 unresolved 0.31
12.81 21.4 0.34 unresolved 0.33
162794757 8.59 20.2 0.28 6.14.0 10 0.25 HD 163376
12.81 30.1 0.42 7.26.2 7 0.3
163334807 8.59 3.6 0.30 problem 0.25 HD 163376
11.85 7.3 0.39 5.03.7 -7 0.31
12.81 13.8 0.43 5.13.4 -12 0.33

163423814
11.85 7.7 0.83 4.34.2 79 0.30 HD 163376
12.81 18.1 0.55 3.63.4 85 0.33
165592957 8.59 5.2 0.33 unresolved 0.37 HD 152980
11.85 8.6 0.36 unresolved 0.40
12.81 10.9 0.41 unresolved 0.40
165944656 8.59 16.6? 1.73 4.93.9 84 0.33 HD 124294
11.85 46.0 1.56 5.94.5 83 0.30
12.81 46.0 1.65 5.24.2 82 0.32
170281004 8.59 44.7 0.33 unresolved 0.33 HD 159187
11.85 48.4 0.36 unresolved 0.35
12.81 56.9 0.38 unresolved 0.37 HD 155066
170475650 11.30 155.2 0.62 5.64.6 8 0.40 Eta Sgr
18.30 179.3 1.10 4.74.1 10 0.57
170884221 8.59 15.0 0.31 unresolved 0.30
11.85 27.0 0.41 unresolved 0.36
12.81 59.1 0.41 unresolved 0.36
171063046 11.85 2.9 0.51 3.93.9 N/A 0.33 HD 157236
12.81 3.7 0.56 4.23.7 N/A 0.35



Table 4: Observed fluxes and sizes of objects.
171503224 8.59 18.3 0.50 3.73.5 -36 0.32 HD 159433
11.85 50.3 0.58 4.23.6 -58 0.34
12.81 81.0 0.56 4.13.6 -62 0.38
171633907 8.59 253 1.23 5.65.6 N/A 0.25 HD 163376
11.85 892 1.53 5.95.8 N/A 0.30
12.81 910 1.52 6.05.8 N/A 0.33
172334330 11.85 10.4 0.29 unresolved 0.30 HD 163376
12.81 10.5 0.33 unresolved 0.33
172434348 8.59 8.6 0.25 unresolved 0.24 HD 124294
11.85 7.8 0.29 unresolved 0.30
12.81 8.6 0.31 unresolved 0.32
172453951 11.85 2.2 0.47 unresolved 0.32 HD 161892
12.81 2.9 0.49 unresolved 0.35
173114924 8.59 3.9 1.13 3.02.8 -90 0.24 HD 163376
11.85 16.8 1.30 5.55.1 -92 0.30
12.81 19.1 1.33 3.83.6 -88 0.33
173473139 8.59 7.6 0.57 4.13.5 -42 0.34 HD 159881
11.85 17.3 0.48 3.93.1 -41 0.36
12.81 30.5 0.52 4.23.3 -41 0.38
174412411 8.59 12.1 0.71 3.73.5 16 0.58 HD 196321
11.85 39.5 0.76 4.23.9 40 0.30
12.81 48.1 0.66 4.03.6 21 0.33
175162525 8.59 46.6 0.25 unresolved 0.24 HD 163376
11.85 42.0 0.29 unresolved 0.30
12.81 42.0 0.33 unresolved 0.33
175303348 8.59 17.2 0.20 unresolved 0.22 HD 163376
11.85 17.0 0.30 unresolved 0.31
12.81 14.3 0.33 unresolved 0.32
17534+2603 8.59 85.4 0.34 unresolved 0.35 HD 163993
11.85 87.2 0.37 unresolved 0.42
12.81 77.3 0.38 unresolved 0.39
180432116 12.81 1.5 0.36 unresolved 0.32 HD 174387
180711727 8.59 11.7 0.34 unresolved 0.33 HD 167036
11.85 22.2 0.38 unresolved 0.35
12.81 41.5 0.38 unresolved 0.38
18095+2704 8.59 18.8 0.39 unresolved 033 HD 169414
11.85 38.7 0.41 unresolved 0.35
12.81 29.0 0.39 unresolved 0.41
18123+0511 8.59 7.3 0.32 unresolved 0.24 HD 163376
11.85 8.9 0.30 unresolved 0.30
12.81 8.4 0.31 unresolved 0.33
181351456 8.59 7.2 0.34 unresolved 0.23 HD 163376
11.85 17.9 0.37 unresolved 0.30
12.81 37.0 0.42 unresolved 0.32
OH12.80.9 8.59 9.3 0.24 unresolved 0.24 HD 163376
11.85 9.9 0.31 unresolved 0.31
12.81 19.7 0.34 unresolved 0.33
181841302 8.59 228.8 0.31 4.03.5 N/A 0.28 HD 161892
11.85 292.1 0.09 0.40.2 N/A 0.32
12.81 345.0 0.07 1.20.8 N/A 0.33
181841623 8.59 1.7 0.41 unresolved 0.28 HD 168415
11.85 0.5 0.52 unresolved 0.31
182761431 8.59 4.4 0.51 2.52.4 N/A 0.48 HD 181410
11.85 18.9 0.51 2.72.6 N/A 0.50
12.81 22.3 0.51 2.52.4 N/A 0.52
8.59 4.5 0.37 1.61.5 8 0.24 HD 196321
11.85 11.9 0.48 3.52.6 9 0.30
12.81 17.4 0.45 2.32.0 9 0.32
182860959 8.59 27.0 0.30 unresolved 0.23 HD 163376
11.85 37.0 0.31 unresolved 0.30
12.81 62.3 0.35 unresolved 0.32
184500148 11.85 21.4 0.44 4.34.1 44 0.31 HD 161096
12.81 31.1 0.49 3.73.3 32 0.32
184600151 8.59 9.2 0.24 unresolved 0.24 HD 161096
11.85 16.7 0.31 unresolved 0.31
12.81 24.6 0.28 unresolved 0.33


Table 5: Observed fluxes and sizes of objects.
190162330 8.59 8.9 0.39 2.01.9 N/A 0.23 HD 198048
11.85 11.8 0.39 2.82.2 N/A 0.30
12.81 12.8 0.39 2.21.6 N/A 0.32
19075+0921 8.59 92.5 0.34 unresolved 0.32 HD 178690
11.85 120.0 0.35 unresolved 0.34
12.81 278.9 0.35 unresolved 0.34
19125+0343 8.59 25.2 0.26 unresolved 0.23 HD 174387
11.85 27.3 0.29 unresolved 0.29
12.81 22.8 0.33 unresolved 0.32
191260708 8.59 644.4 0.79 unresolved (saturated) 0.23 HD 174387
11.85 744.3 0.64 unresolved (saturated) 0.30
12.81 810.6 0.51 unresolved (saturated) 0.32
19114+0002 8.59 2.7 0.27 4.03.7 N/A 0.26 HD 178131
11.85 17.1 0.25 5.24.9 N/A 0.32
12.81 1.7 0.40 5.25.1 N/A 0.33
191323336 8.59 47.8 0.24 unresolved 0.23 HD 163376
11.85 34.4 0.33 unresolved 0.30
12.81 28.8 0.32 unresolved 0.32
19134+2131 11.85 3.9 0.34 unresolved 0.30 HD 196321
12.81 6.2 0.37 unresolved 0.33
191750807 8.59 309.3 0.54 unresolved (saturated) 0.23 HD 163376
11.85 295.9 0.42 unresolved (saturated) 0.30
12.81 298.0 0.34 unresolved 0.34

19192+0922
8.59 150.4 0.38 unresolved 0.31 HD 185622
11.85 181.9 0.37 unresolved 0.34
12.81 159.9 0.38 unresolved 0.37
19244+1115 8.59 611.6 0.51 3.33.2 N/A 0.31 HD 183439
11.85 1655.1 0.52 3.8 3.6 N/A 0.33
12.81 1099.0 0.54 4.03.7 N/A 0.36
19327+3024 8.80 53.8 1.85 7.56.9 84 0.23 HR 7924
9.70 58.0 2.05 7.16.4 80 0.23
11.60 104.0 1.03 7.56.2 80 0.25
18.10 308.0 1.97 7.66.7 84 0.38
19343+2926 8.59 15.2 0.31 unresolved 0.30 HD 186860
11.85 14.3 0.34 unresolved 0.34
12.81 16.1 0.36 unresolved 0.35
19374+2359 8.59 18.7 0.86 3.12.9 9 0.36 HD 185622
11.85 21.6 0.88 3.23.0 10 0.38
12.81 24.5 0.91 3.03.0 N/A 0.40
19386+0155 8.59 14.7 0.39 2.72.5 116 0.48 HD 185622
11.85 18.4 0.46 2.62.6 N/A 0.62
12.81 22.5 0.41 2.22.1 113 0.45
19454+2920 8.59 4.9 0.46 2.11.7 105 0.33 HD 186860
11.85 16.0 0.52 2.62.4 95 0.40
12.81 25.5 0.49 2.42.1 96 0.40
19477+2401 8.59 3.3 0.47 unresolved 0.41 HD 186860
11.85 11.4 0.49 unresolved 0.43
12.81 15.1 0.52 unresolved 0.45
19480+2504 8.59 5.8 0.50 unresolved 0.62 HD 186860
11.85 15.5 0.51 unresolved 0.54
12.81 22.8 0.51 unresolved 0.54
195001709 8.59 problem
11.85 29.3 1.12 3.22.9 85 0.31 HD 188603
12.81 32.9 1.00 3.02.8 87 0.34
20004+2955 8.59 12.4 0.35 unresolved 0.28 HD 189577
11.85 31.5 0.38 unresolved 0.33
12.81 20.9 0.40 unresolved 0.34
20043+2653 8.59 15.3 0.57 unresolved 0.48 HD 189577
11.85 12.9 0.53 unresolved 0.48
12.81 19.7 0.51 unresolved 0.48
200770625 8.59 314.8 0.33 unresolved 0.38 HD 192947
11.85 410.3 0.36 unresolved 0.37
12.81 405.4 0.36 unresolved 0.36
Table 6: Observed fluxes and sizes of objects.
20547+0247 8.59 21.3 0.25 unresolved 0.23 HD 174387
11.85 35.7 0.34 unresolved 0.30
12.81 41.7 0.33 unresolved 0.32
210320024 8.59 230.9 0.42 unresolved (saturated) 0.24 HD 196321
11.85 194.9 0.33 unresolved 0.30
12.81 142.8 0.34 unresolved 0.33
212825050 8.80 30.8 1.84 7.47.1 -16 0.24 HR 8538
9.70 31.0 1.77 6.34.8 -13 0.25
11.60 92.3 1.80 7.35.6 -18 0.27
18.10 165.2 1.87 6.35.1 -20 0.39
221964612 8.59 316.7 0.74 unresolved (saturated) 0.24 HD 196321
223271731 8.59 9.4 0.25 unresolved 0.23 HD 198048
11.85 7.5 0.30 unresolved 0.30
23166+1655 8.59 433.0 0.57 unresolved (saturated) 0.37 HD 220009
11.85 856.7 0.62 unresolved (saturated) 0.39
12.81 942.4 0.56 unresolved (saturated) 0.40















Table 7: Observed fluxes and sizes of objects.
IRAS name Other names MIR morpho C/O type
IRAS 061761036 Red Rectangle Core/Bipolar C/O PPN
IRAS 07134+1005 Elliptical C PPN
IRAS 073991435 OH 231.8 +4.2 Core/Bipolar O PPN
IRAS 101975750 Roberts 22 Core/Multipolar C/O PPN
IRAS 102155916 AFGL 4106 Detached shell C/O PRSG
IRAS 124056219 Asymmetrical HII
IRAS 145625406 Hen 2-113 Tore/elliptical C/O PN
IRAS 151035754 GLMP 405 Core/bipolar O WF
IRAS 154455449 Dark Lane/Bipolar O WF
IRAS 155535230 GLMP 440 Marginally resolved PPN
IRAS 162794757 Core/Multipolar C/O PAGB
IRAS 163334807 Core/Multipolar O WF
IRAS 163423814 Water foutain nebula Dark Lane/Bipolar O WF
IRAS 165944656 Water Lily nebula Core/Bipolar C PPN
IRAS 170475650 CPD-568032 Core/Bipolar C/O PN
IRAS 171063046 Marginally resolved O PPN
IRAS 171503224 Cotton candy nebula Core/Bipolar O PPN
IRAS 171633907 Hen 31379 Detached shell/Spherical O PRSG
IRAS 173114924 LSE 76 Core/Bipolar C PPN
IRAS 173473139 GLMP 591 Core/Multipolar O PN
IRAS 174412411 Silkworm nebula Core/Multipolar O PPN
IRAS 181841302 MWC 922 Square Be
IRAS 182761431 V* V445 Sct Marginally resolved O PPN



IRAS 184500148
W43A Core/Bipolar O WF
IRAS 190162330 Marginally resolved PPN
IRAS 19114+0002 AFGL2343 Detached shell O MES
IRAS 19244+1115 IRC +10420 Core/extended O MES
IRAS 19327+3024 BD+303639 Elliptical PN
IRAS 19374+2359 Detached shell O PPN
IRAS 19386+0155 V1648 Aql Core/extended PPN
IRAS 19454+2920 Core/Extended C PPN
IRAS 195001709 V5112 Sgr Detashed Shell, no central star C PPN
IRAS 20043+2653 GLMP 972 Core/Extended PPN
IRAS 21282+5050 Toroidal C PN


Table 8: Morphologies of the resolved targets, dust properties (C=carbon-rich, O=oxygen-rich, C/O= dual dust chemistry)

Appendix B Images

Figure 4: Michelle/Gemini North imnages of IRAS 06176 (The Red Rectangle). North is up and East left.
Figure 5: Visir images of IRAS 07134 (HD 56126).
Figure 6: Michelle/Gemini North imnages of IRAS 07134 (HD 56126).
Figure 7: Michelle/Gemini North imnages of IRAS 07399 (OH 231.8+4.2).
Figure 8: Visir images of IRAS IRAS 10197 (Roberts 22).
Figure 9: T-Recs images of IRAS 10197(Roberts 22).
Figure 10: Visir burst mode images of IRAS 15103
Figure 11: Visir burst mode images of IRAS 15445
Figure 12: Visir burst mode images of IRAS 15553
Figure 13: Visir burst mode images of IRAS 16279
Figure 14: Visir burst mode images of IRAS 16342 (The Water Fountain).
Figure 15: Visir burst mode images of IRAS 16594 (The Water Lily nebula).
Figure 16: Visir burst mode images of IRAS 17106
Figure 17: Visir burst mode images of IRAS 17150
Figure 18: T-Recs/Gemini images of IRAS 17150 (The Cotton Candy nebula).
Figure 19: Visir burst mode images of IRAS 17311
Figure 20: Visir burst mode images of IRAS 17441.
Figure 21: Visir burst mode images of IRAS 18276.
Figure 22: Visir burst mode images of W43A.
Figure 23: Visir burst mode images of IRAS 19016.
Figure 24: Visir images of IRAS 19347.
Figure 25: Visir burst mode images of IRAS 19386.
Figure 26: Visir burst mode images of IRAS 10197
Figure 27: Visir images of IRAS 19500.
Figure 28: Visir burst mode images of IRAS 20043.
Figure 29: T-Recs images of IRAS 14562 (Hen 2-113).
Figure 30: Visir burst mode images of IRAS 16333
Figure 31: T-Recs/Gemini images of IRAS 17047 (CPD 568032
Figure 32: Visir images of IRAS 17347
Figure 33: T-Recs/Gemini South images of IRAS 19327 (BD+303639
Figure 34: Michelle/Gemini North burst mode images of IRAS 21282.
Figure 35: T-Recs mode images of IRAS 10215 (AFGL 4106).
Figure 36: Visir burst mode images of IRAS 17163.
Figure 37: Visir images of IRAS 19114.
Figure 38: Visir burst mode images of IRAS 19244 (IRC+10420).
Figure 39: Visir burst mode images of IRAS 12405
Figure 40: Visir images of IRAS 18184 (The red Square nebula).

Footnotes

  1. thanks: Based on observations made at the Very Large Telescope at Paranal Observatory under the program 081D.0630
  2. pagerange: A mid-infrared imaging catalogue of post-AGB starsthanks: Based on observations made at the Very Large Telescope at Paranal Observatory under the program 081D.0630 LABEL:lastpage
  3. thanks: Based on observations made at the Very Large Telescope at Paranal Observatory under the program 081D.0630
  4. pubyear: 2002

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