Rotation, activity, and lithium abundance in cool binary starsBased on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated with IAC, and the Automatic Photoelectric Telescopes in Arizona, jointly operated with Fairborn Observatory.

Rotation, activity, and lithium abundance in cool binary starsthanks: Based on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated with IAC, and the Automatic Photoelectric Telescopes in Arizona, jointly operated with Fairborn Observatory.

K. G. Strassmeier Corresponding author. kstrassmeier@aip.de Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany    M. Weber Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany    T. Granzer Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany    Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany    S. Järvinen Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany
20122012
20122012
Abstract

We have used two robotic telescopes to obtain time-series high-resolution optical echelle spectroscopy and and/or photometry for a sample of 60 active stars, mostly binaries. Orbital solutions are presented for 26 double-lined systems and for 19 single-lined systems, seven of them for the first time but all of them with unprecedented phase coverage and accuracy. Eighteen systems turned out to be single stars. The total of 6,609 =55,000 echelle spectra are also used to systematically determine effective temperatures, gravities, metallicities, rotational velocities, lithium abundances and absolute H-core fluxes as a function of time. The photometry is used to infer unspotted brightness, and/or colors, spot-induced brightness amplitudes and precise rotation periods. An extra 22 radial-velocity standard stars were monitored throughout the science observations and yield a new barycentric zero point for our STELLA/SES robotic system. Our data are complemented by literature data and are used to determine rotation-temperature-activity relations for active binary components. We also relate lithium abundance to rotation and surface temperature. We find that 74% of all known rapidly-rotating active binary stars are synchronized and in circular orbits but 26% (61 systems) are rotating asynchronously of which half have and . Because rotational synchronization is predicted to occur before orbital circularization active binaries should undergo an extra spin-down besides tidal dissipation. We suspect this to be due to a magnetically channeled wind with its subsequent braking torque. We find a steep increase of rotation period with decreasing effective temperature for active stars, , for both single and binaries, main sequence and evolved. For inactive, single giants with  d, the relation is much weaker, . Our data also indicate a period-activity relation for H of the form for binaries and for singles. Its power-law difference is possibly significant. Lithium abundances in our (field-star) sample generally increase with effective temperature and are paralleled with an increase of the dispersion. The dispersion for binaries can be 1–2 orders of magnitude larger than for singles, peaking at an absolute spread of 3 orders of magnitude near 5000 K. On average, binaries of comparable effective temperature appear to exhibit 0.25 dex less surface lithium than singles, as expected if the depletion mechanism is rotation dependent. We also find a trend of increased Li abundance with rotational period of form but again with a dispersion of as large as 3–4 orders of magnitude.

Binaries: spectroscopic, stars: fundamental parameters, stars: late-type, stars: rotation, techniques: radial velocities, techniques: photometry, starspots
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1\Yearpublication2012\Yearsubmission2012\Month8\Volume333\Issue8\DOIThis.is/not.aDOI

\publonline

2012

1 Introduction

In a previous paper (Strassmeier et al. [2000]; paper I) we reported on radial and rotational velocities, chromospheric emission-line fluxes, lithium abundances, and rotation periods of a total sample of 1,058 G5–K2 dwarfs, subgiants, and giants based on 1,429 moderate-resolution KPNO coudé spectra and 8,038 Strömgren photometric data points. The aim of this survey was to detect new candidates for Doppler imaging but, besides the discovery of 170 new variable stars and 36 new spectroscopic binaries, the more intriguing result was that 74% of the G-K stars with Ca ii H&K emission also showed significant lithium on their surface. However, G-K giants should have very few lithium on their surface because of convective mixing. Theoretical models predict that surface lithium has to be diluted by many factors once a star arrives at the bottom of the red giant branch (Iben [1967], Charbonnel & Balachandran [2000]). Out of the 21 Doppler imaging candidates found, just four stars were single stars, three of them evolved, the rest were spectroscopic binaries, but all four single stars had very strong lithium.

Despite that it is generally acknowledged that higher than normal lithium abundance is common among magnetically active stars, no unique correlation with rotation rate was found after Skumanich’s ([1972]) original discovery. Recently, White et al. ([2007]) revisited this issue in their sample of solar-type dwarfs but no such correlation was found. Almost all surveys just revealed trends, if at all, and even these appear to be of different quality (e.g. Lébre et al. [2006]; Böhm-Vitense [2004]; do Nascimento et al. [2000], [2003]; De Medeiros et al. [2000]; De Laverny et al. [2003]; Randich et al. [1993]). The comprehensive survey of nearby giants by Luck & Heiter ([2007]) did not even show a trend. However, the line broadening in their stellar sample was just 3–7 km s and likely too narrow a range to see a trend. Böhm-Vitense ([2004]) suggested that the steep decrease of in early G giants as well as in Hyades F dwarfs at effective temperatures cooler than 6,450 K, i.e. at their lithium dip at about the same temperature, are the result of deep mixing and related to the merging of the hydrogen and the helium convection zones. More recently, Takeda et al. ([2010]) announced evidence for a (positive) correlation of Li abundance with rotational velocity in a sample of solar-analog stars.

The spectroscopic survey of 390 solar-like dwarf stars by White et al. ([2007]) included 28 of the stars in our survey. Relating Ca ii H&K radiative losses to stellar rotation, White et al. ([2007]) found a saturation of chromospheric emission for rotational velocities above approximately 30 km s. In an earlier paper, Strassmeier et al. ([1994]) verified that evolved stars obey qualitatively the same scaling of Ca ii-K-line flux with stellar rotational velocity or period as do main-sequence stars (see, e.g., Mamajek & Hillenbrand [2008], Pace & Pasquini [2004], or Pizzolato et al. [2003] for a summary). No qualitative difference was found between single evolved stars and their equally rapidly rotating counterparts in a spectroscopic binary. However, large scatter indicated that rotation might not be the only relevant parameter. Based on a sample of 22 intermediate-mass G and K giants in close binaries, Gondoin ([2007]) not only verified the rotational dependency of (coronal) X-ray surface flux but also found a dependency on surface gravity. Such a dependence could stem from the effect of gravity on coronal electron density and on the overall sizes of coronal loops.

Massarotti et al. ([2008]) reported rotational and radial velocities for 761 giants within 100 pc of the Sun. They found that all binaries in their sample with periods less than 20 days have circular orbits while about half the orbits with periods between 20–100 days still showed significant eccentricity. They also found evidence that the rotational velocity of horizontal branch stars is larger than that of first-ascend giants by a few km s. Earlier, De Medeiros et al. ([2002]) presented a study of 134 late-type giants in spectroscopic binaries and found a considerable number of G-K giant stars with moderate to moderately-high rotation rates. These rotators have orbital periods shorter than 250 days and circular or nearly circular orbits and appear to be synchronized with the orbit.

The present paper follows up on the newly identified spectroscopic binaries with active components from our paper I. Its direct aim is to determine their orbits on the basis of high-precision radial velocities and to separate their component’s rotation and activity tracers along with other absolute astrophysical parameters. Only with precise stellar parameters can we directly compare binary components with single stars and then be aware of the spectrum contamination from unknown secondaries or even tertiary stars. We recall that an unknown continuum contribution from a secondary star impacts on the determination of the effective temperature, gravity etc. and could together drastically alter the derived lithium abundances and thereby mask any relation if present. In Sect. 2 we restate our sample selection criteria and give a summary of the target stars. In Sect. 3 we describe the new observations and in Sect. 4 we derive basic quantities from the spectra and the light curves. These include radial velocities, orbital parameters, rotational velocities and photometric periods, stellar atmospheric parameters like temperature, gravity and metallicity, lithium abundances, and absolute H-core fluxes. Sect. 5 lists notes to individual stars. Sect. 6 presents the analysis in terms of rotation, temperature, activity, and lithium-abundance relations. Finally, Sect. 7 summarizes our findings and conclusions.

2 Sample selection

Our sample selection is based on the 1,058 stars from the KPNO Doppler-imaging candidate survey in paper I. It itself was drawn from a total of 6,440 stars from the Hipparcos catalog (ESA [1997], van Leeuwen [2007]) for the brightness range 7\fm0–9\fm5 and declination through +70, colors between 0\fm67 and 1\fm0 for stars with parallaxes  mas (i.e. G5–K3 dwarfs) and between 0\fm87 and 1\fm2 for  mas (i.e. G5–K2 giants and subgiants). These criteria were imposed to select stars with a significant outer convective envelope where the likelihood of detecting magnetic activity is highest. Out of the 1,058 stars, 371 (35%) were found with Ca ii H&K emission but only 78 (7.3%) with 10 km s. On the contrary, a lithium line was detected in 283 (74%) of all stars that had Ca ii emission (with 58% of the stars with lithium above 10 mÅ). Out of a subsample of 172 stars with moderate to strong Ca ii emission, 168 (97.7%) turned out to be photometric variable and for 134 a photometric (rotational) period could be obtained. Finally, 36 targets were single-lined spectroscopic binaries (SB1), of which 17 were new detections. A further 16 targets were found “possible SB1s”. An additional 30 targets were double-lined spectroscopic binaries (SB2), of which 19 were new detections. Two targets were even triple lined (SB3) of which one was a new detection and another four were new candidates. All along, there were a few misidentifications and misinterpretations as well as unrecognized literature entries. Whenever recognized, we try to clarify these in the present paper.

Figure 1: HD 171067 as an example for a STELLA/SES spectrum. The top panel shows the entire wavelength coverage from 3880–8820 Å. Note the increasing inter-order gaps starting around 7340 Å. The lower panels zoom into three wavelength regions employed in this paper for analysis; from left to right, one of the five échelle orders that are used for the PARSES spectrum-synthesis fit (thick line), the Balmer H line, and the region around the neutral lithium line at 6708 Å. HD 171067 (=7\fm2) is an inactive single, slightly evolved, G8 star with  km s. Exposure time was 1200 s.

We now present time-series observations of all those targets in the survey that were previously unknown or suspected spectroscopic binaries in 2000. This sample comprised 59 stars presented in this paper. One additional star was added because of its comparable uncertain orbit despite being a fourth magnitude star ( UMi). During the final observational stages for the present paper we learned that Griffin ([2009]), Griffin ([2010]) and Griffin & Filiz Ak ([2010]) had picked up many of our original SB candidate stars from paper I that found their way into the new edition of the CABS catalog (Eker et al. [2008]), and independently determined orbital elements. We compare our results whenever possible. Stellar identifications and some basic observable properties for all our target stars are summarized in Table 1. Note that three of the stars actually do not show significant Ca ii H&K emission and would not be dubbed magnetically active but are left in the sample because they were monitored initially in order to search for signs of binarity. All three turned out to be single stars though. Altogether, 18 of the SB1 candidates were found to be single with some of them still members of a visual-binary system. These stars are also in Table 1 but are summarized in a separate table later in the paper. In one case the two components of a wide visual binary (BD+11 2052AB = ADS 7406AB) were treated as separate stars throughout the paper. One double-lined binary (HD 16884) turned out to be actually a quadruple system with both pairs being SB1. First orbit determinations are presented for seven systems (HD 50255, HD 82841, HD 106855, HD 147866, HD 190642, HD 199967, and HD 226099).

3 New observations and data reductions

3.1 High-resolution optical spectroscopy

Time-series high-resolution echelle spectroscopy was taken with the 1.2 m STELLA-I telescope between June 2006 and May 2012. Most spectra were exposed just long enough to measure a precise radial velocity and had S/N of between 40–80:1 but several spectra per target were exposed to reach S/N well above 100:1. A total of 6,609 spectra for a total of 60 stars were obtained over the course of approximately six years. STELLA-I is a fully robotic telescope that, together with STELLA-II, makes up the STELLA observatory at the Izãna ridge on Tenerife in the Canary islands (Strassmeier et al. [2004], [2010]). The fiber-fed STELLA Echelle Spectrograph (SES) is the telescope’s only instrument. It is a white-pupil design with an R2 grating with two off-axis collimators, a prism cross disperser and a folded Schmidt camera with an E2V 2k2k CCD as the detector. All spectra have a fixed format on the CCD and cover the wavelength range from 388–882 nm with increasing inter-order gaps near the red end starting at 734 nm towards 882 nm. The resolving power is =55,000 corresponding to a spectral resolution of 0.12 Å at 650 nm (3-pixel sampling). An example spectrum is shown in Fig. 1. We note that the SES received a major upgrade in summer 2012 with a new cross disperser, a new optical camera, and a new CCD. A bit earlier, the SES fiber was moved to the prime focus of the second STELLA telescope in 2011. Further details of the performance of the system were reported by Weber et al. ([2012]) and Granzer et al. ([2010]).

HD Var. name HIP SAO Sp.type SB Ref.
\objectHD 553 V741 Cas 834 11013 8.17 1.03 K0 SB2 121 1320 s,34
\objectLN Peg 999 91772 8.59 0.81 K0 SB2+1 135 1302 r
\objectHD 8997 EO Psc 6917 74742 7.74 0.96 K2/K1-K6V SB2 165 1453 b
\objectHD 9902 BG Psc 74827 8.71 0.63 F5-6V/G9-K0IV SB2 95 748 a,c
\objectHD 16884 110699 8.94 1.37 K4III 2SB1 83 1046 a,e
\objectHD 18645 FU Cet 13968 130230 7.86 0.75 G2III-IV S 70 784 f
\objectHD 18955 IR Eri 14157 148731 8.45 0.82 K0V/K2-3V SB2 67 1446 g
\objectHD 23551 MM Cam 18012 12924 7.11 0.91 K0III S 101 836
\objectHD 24053 17936 111446 7.7 0.8 G0 S 77 803
\objectAI Lep 150676 8.97 0.57 G6IV/G0V S 93 1460 l
\objectHY CMa 151224 9.33 1.00 K0-3V-IV/K1V-IV SB2 87 1782 l
\objectHD 40891 28935 13714 8.40 0.85 G5 SB1 85 1380 h
\objectHD 43516 29750 151290 7.37 0.85 G8III S 57 830
\objectHD 45762 V723 Mon 30891 133321 8.30 0.87 G0 SB2+1 89 1231 z
\objectHD 50255 32971 152024 7.43 0.68 G4.5V SB2 66 1471
\objectHD 61994 38018 6310 7.08 0.67 G0 SB2 105 899 t
\objectHD 62668 BM Lyn 38003 41995 7.73 1.10 K0III SB1 137 2000 a,f,i
\objectHD 66553 39515 97536 8.48 0.85 G5 SB1 92 2001 h
\objectHD 73512 42418 116990 7.91 0.90 K0V/K4V SB2 74 892 a
\objectHD 76799 44007 176747 7.11 0.99 K0III S 75 1442
46634 98614 8.76 0.86 G5 VB,S 96 1129 y
\objectHD 82159 GS Leo 46637 98615 8.85 0.92 G9V VB,SB1 107 1458 u,32
\objectHD 82286 FF UMa 46919 14919 7.89 0.96 G5 SB2 161 1446 i,31,35
\objectHD 82841 OS Hya 46987 136965 8.45 1.08 K2 SB1 61 1447
\objectEQ Leo 50072 99011 9.39 1.09 K1III SB1 62 1169 a
\objectHD 93915 53051 43492 8.07 0.68 G5V/G6V SB2 85 1169 a
\objectHD 95188 XZ LMi 53747 81610 8.45 0.74 G8V S 85 891 v,j
\objectHD 95559 GZ Leo 53923 81634 8.83 0.96 K0V/K2V SB2 113 1162 k,30
\objectHD 95724 YY LMi 54028 62375 8.96 0.94 G5V S 76 856 v
\objectHD 104067 58451 180353 7.93 0.99 K2V S 76 887
\objectHD 105575 QY Hya 59259 180519 9.04 0.93 (K5/M1)/G4 SB3 51 1164 29
\objectHD 106855 UV Crv 59914 180648 9.59 0.81 K1V SB2,VB 88 1227
\objectHD 108564 60853 9.45 0.98 K5V S 70 867
\objectHD 109011 NO UMa 61100 28414 8.10 0.94 K2V SB2 184 1629 o
\objectHD 111487 IM Vir 138983 9.69 0.64 G5 SB2 106 1292 p
\objectHD 112099 62942 119652 8.23 0.86 K1V SB1 80 1142 a
63322 63275 9.27 0.84 G6V VB,SB1 104 937 y,32
\objectHD 112859 BQ CVN 63368 44410 8.09 0.92 F5V/K0III-IV SB2 93 1249 a,w
\objectCD CVn 63442 44421 9.39 1.19 K0III SB1 85 1165 a
\objectHD 120205 67344 158174 8.3 0.9 G5 S 93 849
\objectHD 127068 HK Boo 70826 101044 8.43 0.89 G8V/G5-8IV SB2 99 1257 a
\objectHD 136655 75132 83780 9.01 0.9 K0 S 122 842 z
\objectHD 138157 OX Ser 75861 101580 7.14 1.02 K0III SB1 148 1086 u,32
\objectV381 Ser 77210 121177 9.16 0.83 K2V SB2 96 1114 33
\objectHD 142680 V383 Ser 77963 101816 8.71 0.95 K0-2V/K7V SB2 90 781 a,v
\objectHD 143937 V1044 Sco 78708 184077 8.65 0.91 G9V/M0V SB2 86 1131 l
\objectHD 147866 V894 Her 80302 84343 8.1 1.1 K0 SB1 115 1269
\objectHD 150202 GI Dra 81284 30015 7.97 0.93 K0III SB1 179 1112 a
\objectHD 153525 V1089 Her 83006 46403 7.88 1.04 K0V S 196 1349 x
\objectHD 153751  UMi 82080 2770 4.22 0.88 G5III SB1 220 2144 d
\objectHD 155802 84303 141567 8.51 0.89 K3V S 114 857
\objectHD 171067 90864 103819 7.19 0.696 G8V S 143 857
\objectHD 184591 96280 104991 7.37 0.85 G5 S 155 842 x,z
\objectHD 190642 V4429 Sgr 99042 163264 8.08 0.99 F6-8V/K1III-IV SB1 196 1274
\objectHD 197913 OR Del 102490 106466 7.55 0.76 G6V/G8V SB2 194 1848 m
\objectHD 199967 103454 8.01 0.58 G5 SB2 121 945
Table 1: Summary of program stars and name aliases. Listed are the Tycho brightness and the color in magnitudes, the spectral classification if available, the binarity according to this paper (S=single star, SB=spectrosopic binary, SB1=single-lined SB, SB2=double-lined SB, SB3=triple-lined, VB=visual binary), the number of STELLA spectra obtained and used for the orbit determination, its time span covered (), and a primary reference if existent.
HD Var. name HIP SAO Sp.type SB Ref.
\objectHD 202109  Cyg 104732 71070 3.20 0.99 G8III SB1 150 1288 n
\objectHD 218739 114385 52754 7.14 0.61 G5 S 107 791
\objectHD 226099 97640 68946 8.01 0.783 G5 SB2 209 1334
\objectHD 237944 53209 27812 9.36 0.71 (G8V+/G8V+)/? SB3 119 1431 a,q

References. a: Griffin (2009), b: Griffin (1987), c: Cutispoto et al. (2003), d: Climenhaga et al. (1951), e: Favata et al. (1993), f: Fekel (1997), g: Fekel et al. (2004), h: Latham et al. (2002), i: Henry et al. (1995), j: Wright et al. (2004), k: Karatas et al. (2004), l: Cutispoto et al. (1999), m: Griffin (2005), n: Griffin & Keenan (1992), o: Halbwachs et al. (2003), p: Morales et al. (2009), q: Otero & Dubovsky (2004), r: Fekel et al. (1999), s: Duemmler et al. (2002), t: Duquennoy & Mayor (1988), u: Gálvez et al. (2006), v: Barnes (2007), w: Montes et al. (2000), x: Strassmeier (1994), y: Gálvez et al. (2005), z: Griffin (2010), 29: Szalai et al. (2007), 30: Gálvez et al. (2009), 31: Gálvez et al. (2007), 32: Griffin & Filiz Ak (2010), 33: Goldberg et al. (2002), 34: Griffin (2003), 35: Griffin (2012).

Table 1: (continued)
HD Name Class.
\objectHD 3712 Cas K0 II-III 230 –3.863 0.094 –4.31 +0.447
\objectHD 4128 Cet K0 III 143 +13.686 0.107 +13.1 +0.586
\objectHD 12929 Ari K2 III 440 –14.138 0.118 –14.64 +0.502
\objectHD 18884 Cet M2 III 60 –25.688 0.293 –26.08 +0.392
\objectHD 20902 Per F5 Ib 152 –1.800 0.138 –2 +0.200
\objectHD 25025 Eri M0 III 26 +61.159 0.217 +61.1 +0.059
\objectHD 29139 Tau K5 III 503 +54.646 0.188 +54.26 +0.386
\objectHD 36673 Lep F0 Ib 53 +25.871 0.413 +25.2 +0.671
\objectHD 62509 Gem K0 III 442 +3.783 0.076 +3.23 +0.553
\objectHD 81797 Hya K3 III 203 –4.033 0.076 –4.7 +0.667
\objectHD 84441 Leo G0 II 165 +5.001 0.046 +4.5 +0.501
\objectHD 107328 16 Vir K0.5 III 332 +37.117 0.160 +36.4 +0.717
\objectHD 109379 Crv G5 II 49 -6.947 0.069 –7.6 +0.653
\objectHD 124897 Boo K1.5 III 787 –4.871 0.149 –5.3 +0.429
\objectHD 146051 Oph M0.5 IIIab 146 –19.133 0.146 –19.6 +0.467
\objectHD 156014 Her M5Ib-II 303 –31.168 0.694 –32.09 +0.922
\objectHD 161096 Oph K2 III 763 –11.844 0.095 –12.53 +0.686
\objectHD 168454 Sgr K2 III 18 –19.798 0.035 –20.4 +0.602
\objectHD 186791 Aql K3 II 538 –2.430 0.261 –2.79 +0.360
\objectHD 204867 Aqr G0 Ib 80 +6.808 0.151 +6.3 +0.508
\objectHD 206778 Peg K2 Ib 572 +3.588 0.262 +3.39 +0.198
\objectHD 212943 35 Peg K0 III 402 +54.740 0.111 +54.16 +0.580
Weighted average +0.503

Double star with the A component being a “semiregular pulsating variable”.

Table 2: STELLA radial velocities of standard stars. is the total number of spectra. is the average radial velocity from STELLA spectra, its standard deviation, and the CORAVEL velocity from Famaey et al. ([2005]) or, if not in Famaey et al., from Udry et al. ([1999]). The velocity difference STELLA-minus-CORAVEL is given in the last column. The averaged offsets from all stars weighted by the number of data points is given in the last line. All velocities are in km s.

SES spectra are automatically reduced using the IRAF111The Image Reduction and Analysis Facility is hosted by the National Optical Astronomy Observatories in Tucson, Arizona at URL iraf.noao.edu.-based STELLA data-reduction pipeline (Weber et al. [2011]). The images were corrected for bad pixels and cosmic-ray impacts. Bias levels were removed by subtracting the average overscan from each image followed by the subtraction of the mean of the (already overscan subtracted) master bias frame. The target spectra were flattened by dividing by a nightly master flat which has been normalized to unity. The nightly master flat itself is constructed from around 50 individual flats observed during dusk, dawn, and around midnight. After removal of the scattered light, the one-dimensional spectra were extracted with the standard IRAF optimal extraction routine (Horne [1986]). The blaze function was then removed from the target spectra, followed by a wavelength calibration using consecutively recorded Th-Ar spectra. Finally, the extracted spectral orders were continuum normalized by dividing them with a flux-normalized synthetic spectrum of the same spectral classification as the target in question.

3.2 VI and by photometry

Johnson-Cousins and/or Strömgren photometry of 56 of the targets were obtained with the Amadeus (T7) and/or the Wolfgang (T6) automatic photoelectric telescope (APT) at Fairborn Observatory in southern Arizona, respectively. These 56 stars are listed in Table 6 along with the analysis results. A total of 16,591 observations in either or pairs were obtained. Typically, one APT observation consists of three ten-second (30 s for Strömgren) integrations on the variable, four integrations on the comparison star, two integrations on the check star, and two integrations on the sky. A 30\arcsec diaphragm was used for all targets. The standard error of a nightly mean for Amadeus from the overall seasonal mean changed over the past decade but was typically 4–6 mmag in and 6–8 mmag in for the brightness range of stars in this paper. The observing seasons between 2007–2009 showed increasing scatter due to a slowly but systematic malfunction of the acquisition CCD camera. By late 2009 it got so bad that we had to exchange the entire camera plus its CCD and after that, starting with HJD 2,455,143, the scatter was back to the original values quoted above. The standard error of a nightly mean for Wolfgang was between 1.2–3 mmag, depending on system brightness. For further details we refer to Strassmeier et al. ([1997]) and Granzer et al. ([2001]).

From concurrent observations of Johnson standards in , we also deduce an all-sky solution and apply it to the differential values whenever feasible. Its accuracy never significantly exceeds 0\fm01 in though. In case data were taken, can be determined only relative to the comparison star because our all-sky standards were not observed in the band due to time constraints. Absolute errors are typically around 0\fm01 for except for the time period 2007–2009, as mentioned above, and was then likely 0\fm02.

4 Data products

4.1 Radial velocity precision and zeropoint

Radial velocities were determined from an order-by-order cross correlation with a synthetic template spectrum from an ATLAS9 atmosphere (Kurucz [1993]) that roughly matches the target spectral classification. A two-dimensional cross correlation is performed in case the target is double lined. Each of 19 selected echelle orders gives one relative radial velocity. These velocities are then weighted according to the spectral region depending on the amount of available spectral lines and are then averaged. The true internal error is likely close to the rms of these relative velocities. Numerical simulations of the cross correlation errors from synthetic spectra and various two-Gaussian fits to its peaks are discussed in the paper by Weber & Strassmeier ([2011]). Note that the external rms values were significantly larger during the initial year of STELLA operation in 2006/07 (120 m s), compared to thereafter (30 m s). The final radial velocities of our program stars are barycentric and corrected for Earth rotation. No gravitational redshift corrections are applied.

Name Note
(days) (km s)
HD 18645 784 –2.1510.052 =21.5d
HD 23551 836 –6.9250.043 =81.7d
HD 24053 803 +4.8520.040
SAO150676 1460 +25.690.53 =1.79d
HD 43516 830 +21.8460.059
HD 76799 1442 –31.0150.187 =50.13d
\objectHIP 46634 1129 +27.9270.047 Var. but no
HD 95188 891 +6.4390.051 =7.00d
HD 95724 856 +3.3650.055 =11.49d
HD 104067 887 +15.3550.066
HD 108564 867 +111.3630.009
HD 120205 849 –28.8700.048
HD 136655 842 –31.9210.035
HD 153525 1349 –6.8440.039 =15.4d
HD 155802 857 –32.7110.033
HD 171067 857 –45.7710.042
HD 184591 842 –37.6350.044 =48.9d::
HD 218739 791 –5.2010.040

Without Ca ii H&K emission according to our paper I and thus not an active star.

Table 3: Average radial velocities for the single stars. is the time span of STELLA observations in days from Table 1. is the average radial velocity and its standard deviation. Radial-velocity variations are detected for some of the stars due to stellar rotation and an asymmetrically spotted surface. Rotation periods, , if existent, are given in days.

Table 2 lists our standard-star measurements. A total of 22 radial-velocity standards were monitored since mid 2006. Their velocities were derived similarly from cross correlations with a synthetic template spectrum that fitted the star’s classification. Among these standards are often observed bright giant stars like  Oph,  Ari,  Gem,  Tau, 16 Vir, a.o., which are all IAU radial-velocity standards (see Scarfe et al. [1990]). These spectra are also used to identify two epochs in our data when all stars on the observing menu showed a constant offset in velocity. These epochs are identified with two of our hardware maintenance episodes where the fiber injection unit had been readjusted. The average offsets determined from above standard stars were  km s and  km s for the epochs 2,453,902–4,085 and 2,454,192–435, respectively. These corrections were applied to all data in this paper.

The preliminary zero point determination in Strassmeier et al. ([2010]) from four standard stars ( Oph,  Cas,  Gem,  Cet) showed an offset of the STELLA spectra by +0.46 km s with respect to the CORAVEL system defined by Udry et al. ([1999]). In the present paper, we revise this value to +0.503 km s from 22 standard stars. The weights applied for this average shift are the total number of spectra per radial-velocity standard. Note that an absolute heliocentric zero point for STELLA has not been determined yet, e.g. by using asteroids. All velocities in the present paper are on the STELLA system.

Figure 2: Velocity curves for the STELLA single-lined orbital solutions. The dots are the observations and the lines are the orbital fits. Velocities are in km s and the horizontal axes are in orbital phase. The horizontal dashed line in each plot indicates the systemic velocity. STELLA data are shown as filled dots. For HIP 999, the triangles are from Fekel et al. ([1999]). For HD 105575, values from paper I are shown as down-ward pointing triangles, the one FEROS point as a diamond, and the two HARPS points as upward-pointing triangles. For the other long-period system, HD 202109, data from Griffin & Keenan ([1992]) are added and shown as triangles.
Figure 2: (continued).
Figure 3: Velocity curves for the STELLA double-lined orbital solutions. The primary velocities are plotted as filled dots, the secondaries as open circles. Otherwise as in Fig. 2. For HD 237944 the triangles mark the tertiary component.
Figure 3: (continued).
Figure 3: (continued).

Table 3 lists the stars in our sample that were found to exhibit no orbital-induced radial velocity variations, i.e. are presumably single stars. These stars are mostly still very active stars and further investigation with the present time-series data are forthcoming. Several of them, e.g. SAO 150676 or HD 76799, show periodic radial-velocity variations with amplitudes of the order of 1 km s, which we interpret to be due to stellar rotation. Few of our single-star survey targets in paper I were also revisited by Griffin ([2010]), most notably HD 136655 and HD 184591, for which we recommend to read his “Notes on the six constant-velocity stars” for their observational history.

4.2 Binary orbits

For single-lined (SB1) as well as double-lined (SB2) binaries we solve for the components using the general least-square fitting algorithm MPFIT (Markwardt [2009]). For solutions with non-zero eccentricity we use the prescription from Danby & Burkardt ([1983]) to calculate the eccentric anomaly. Usually, we first determine the orbit for both components separately and then combine the two and give rms values for both. Eclipsing binaries were treated slightly separately due to the Rossiter-McLaughlin effect in the radial-velocity curve. Some of the velocities around the two conjunctions were discarded by applying 3- clipping. Most of the orbits are sampled nearly perfectly due to robotic scheduling (Granzer et al. [2001]) but the unexpected high eccentricity in three systems left some phase gaps during periastron. The STELLA time coverage does not exceed 5.9 years, typical values are around 3.3 years. Although partly compensated for by the high velocity precision and the dense sampling, systems with periods longer than, say, 200 days, have comparably uncertain orbital periods. Whenever there were literature data for the eight systems with orbital periods in excess of 100 d that expanded the total time range and improved the orbit, these are included in the period determination. This was the case for HIP 999, HD 105575(ab)c and HD 202109. Otherwise, the orbits are computed from STELLA radial velocities alone. The resulting elements and their errors are summarized in Table 4 and Table 5 for the single-lined and the double-lined systems, respectively. Assuming that the fit is of good quality, we derive the element uncertainties by scaling the formal one-sigma errors from the covariance matrix using the measured values. is a time of periastron or, if the orbit is circular, a time of maximum positive radial velocity. Note that we give orbital periods as observed and not corrected for the rest frame of the system.

The computed radial-velocity curves are compared with our observed velocities in the series of panels in Fig. 2 and Fig. 3 for the single-lined orbits and the double-lined orbits, respectively. Note that two of the four triple systems, HIP 999 and HD 105575, appear in both figures. The latter system is even triple lined. The third triple system, HD 237944, is also triple lined and consists of an SB2 in a short orbit but with the third component in a wide thousands-of-years orbit around the close pair. The fourth triple system is HD 45762 where the secondary is again an SB1 but with a period exactly 1/3 of the wide SB2 pair. HD 106855 is a close visual double with its primary A-component to appear double lined, its bona-fide more massive Ab component being again an SB1 for itself. HD 16884 appears to be a quadruple system with two SB1 pairs in a bound 106.65-d orbit. More comments to individual systems are collected in Sect. 5. Note that these comments do not intend to give a comprehensive overview of CDS/Simbad-collected literature but are meant to draw attention to some specific system features.

Name K rms
(days) (HJD 245+) (km s) (km s) (deg) (10 km)
HIP999(ab)c 1555. 0885.7 5.99 –0.10 0 128. 0.0348 1.154
HD 16884ab 106.63 4088.3 29.97 2.23 0.0161 266. 43.93 0.2978 0.261
0.011 1.6 0.045 0.031 0.0014 5.2 0.066 0.0013
HD 16884cd 106.7 4115.6 16.3 2.3 0 24.0 0.0482 2.215
0.17 0.77 0.38 0.26 0.56 0.0034
HD 40891 0.080
HD 62668 0.294
HD 66553 0.130
HD 82159 0.242
0.000006
HD 82841 0.092
HIP50072 301. 0.310
0.0043 18
HD105575 4550. 4061. 10.11 20.03 186.8 582. 0.381 0.160
52
HD112099 0.067
HIP63322 0.119
0.000005
HIP63442 0.266
HD138157 83. 0.216
0.0009 9.9
HD147866 0.076
HD150202 0.083
 UMi 0.121
HD190642 314. 0.445
HD202109 6446. 2421363. 3.30 40.7 284. 0.413
0.016 3.3

Time of periastron, or ascending node for circular orbits.
Triple system. Orbit (ab) around c is given.
Quadruple system with two SB1 pairs in a synchronized orbit.
SB1 orbit of the tertiary component, , around the close (eclipsing) pair.
SB1 with long period. The orbit given is from a combination of STELLA data and selected published values. is 2421363. See individual notes.

Table 4: STELLA single-lined orbital solutions. Column “rms” denotes the quality of the orbital fit for a point of unit weight in km s.

At the time of the start of our monitoring program in 2006, a total of 17 stars were already either known binaries or had even an orbit computed, or at least had an orbital period known. However, we accumulated enough observations for all systems to allow for orbital solutions just using our own data for a certain epoch. This was motivated not only by consistency arguments but also by detections of orbital-period variations in active binaries and particularly in one of our targets (FF UMa; Gálvez et al. [2007])222See our individual notes for this star though.. Orbital-period variations of magnetically active binaries are known for a long time (e.g. Hall & Kreiner [1973]; see also Lanza et al. [2006]) and were partly explained by mild mass exchange and mass loss due to a stellar wind. However, Applegate ([1992]) proposed a connection between the gravitational quadrupole moment and the shape of a magnetically active component in the system as it goes through its magnetic activity cycle. Therefore, it appears rewarding to redetermine the orbits of such binaries from time to time.

Name Period rms
rms
(days) (HJD245+) (km s) (km s) (deg) (10 km) (M) (km s)
HD 553 0.411
0.390
HIP 999 1.8441405 4063.6374 0.519
0.00055
3.292
HD 8997 0.365
0.400
HD 9902 0.201
0.154
HD 18955 0.237
0.480
SAO151224 1.130
0.869
HD 45762 84.6 0.533
0.0009 3.7
6.4
HD 50255 0.150
0.176
HD 61994 0.118
0.117
HD 73512 0.087
0.170
HD 82286 0.025
0.174
HD 93915 0.180
0.196
HD 95559 0.106
0.165
HD105575 8.6
13
Table 5: STELLA double-lined orbital solutions. Suffices 1 and 2 denote the primary and the secondary star, respectively.
Name Period rms
rms
(days) (HJD245+) (km s) (km s) (deg) (10 km) (M) (km s)
HD106855 1.811
0.0000026
9.92
HD109011 0.094
0.147
HD111487 0.268
1.776
HD112859 0.300
0.265
HD127068 161. 0.190
0.00087 5.5
0.364
HIP77210 0.052
0.203
HD142680 0.042
0.205
HD143937 0.285
1.258
HD197913 0.100
0.161
HD199967 170. 0.102
0.00015 3.5
0.149
HD226099 0.086
0.182
HD237944 105. 0.264
0.0003 1.3
0.223

Time of periastron, or ascending node for circular orbits.
SB2, but with a third component determined from the -residuals. The third-component orbit is given in the SB1 list in Table 4. See also the individual notes.
Hierarchial triple system with lines from components and . The orbit is SB1 with =19.933 d. See individual notes.
SB3 with a third component in the spectrum denoted . Its orbit around the (eclipsing) pair is given in Table 4.
SB3. The third component, , has a median velocity of –12.251.3(stdev) km s for the time of our observations.

Table 5: (continued)
HD/name HD/cmp HJD start Tel. C.I. Note
star (2,4+) (mag) (mag) (mag) (days)
HD 553 443 51107 253 T6+7 217 8.15 0.10 rotation
HD 553 0.28 9.0610.002 eclipsing
HIP 999 977 50395 700 T6 134 8.53 0.08 0.56 1.844750.00008
HD 8997 9472 51098 95 T6 69 7.75 0.02 10.540.11
HD 9902 HIP7910 51098 112 T6 122 8.68 0.05 7.4450.02
HD 16884 17030 51434 3327 T6+7 286 8.87 0.16 1.58 65.440.05
HD 18645 18668 51098 727 T6 241 7.85 0.04 0.55 21.50.1
HD 18955 19223 51099 50 T6 29 8.46 var at
HD 23551 24513 51447 3729 T6+7 242 7.08 0.035 0.94 81.690.03 from T6
HD 24053 23570 55570 74 T7 130 7.72 0.06 0.55
SAO 150676 37792 51434 745 T6+7 389 9.09 0.08 0.79 1.78890.0003
HD 40891 42756 55570 60 T7 71 8.42 0.06 0.76
SAO 151224 43306 51079 4160 T7 1352 9.27 0.39 1.27 rotation
SAO 151224 0.68 4.982420.00003 eclipsing
HD 43516 44396 55576 67 T7 82 7.40 0.03 0.85
HD 45762 45168 55576 49 T7 61 8.35 0.15 0.98 62.01.6 +ellipticity
HD 50255 50674 55576 49 T7 38 7.48 0.05 0.62
HD 61994 63748 55576 49 T7 43 7.05 0.03 0.64
HD 62668 64106 51457 3782 T7 568 7.46 0.40 1.18 67.4700.007
HD 66553 65257 55576 29 T7 6 8.52 0.02 0.72
HD 73512 73764 55572 92 T7 131 7.92 0.02 0.80
HD 76799 77361 55572 92 T7 133 7.25 0.06 0.92
HD 82159 82410 51242 89 T6 52 7.97 0.05 3.0550.003 polluted
HD 82286 82719 51459 3780 T7 609 7.84 0.16 1.12 3.276290.00003
HD 82841 83046 51476 3763 T7 914 8.22 0.07 1.15 56.580.04
HIP 50072 88853 51242 96 T6 58 9.44 0.12 33.7820.009
HD 93915 95379 55572 138 T7 156 8.10 0.20 0.65
HD 95188 94996 51249 102 T6 77 8.51 0.025 7.000.06
HD 95559 95242 51551 3686 T6+7 1061 8.83 0.08 0.93 1.5170004 10
HD 95724 96778 51239 112 T6 78 8.97 0.05 11.490.02
HD 104067 104414 55572 168 T7 158 7.98 0.05 0.92
HD 105575 105814 51239 20 T6 101 8.98 0.62 rotation
HD 105575 0.36 0.292380.00009 eclipsing
HD 106855 106991 51551 3685 T7 992 9.35 0.11 1.27 0.67052586 10
HD 108564 108599 55572 168 T7 203 9.50 0.06 1.02
HD 109011 109894 51225 135 T6 60 8.10 0.02 8.40.2
HD 111487 111276 51142 4116 T7 1571 9.62 0.15 0.86 rotation
HD 111487 0.76 1.308590.000007 eclipsing
HIP 63322 113168 51240 65 T6 35 8.89 0.08 2.2270.003 FAP 20%
HD 112099 111733 55569 171 T7 171 8.22 0.04 0.70
HD 112859 112220 51225 135 T6 76 8.23 0.06 18.340.05
HIP 63442 113828 51240 120 T6 80 9.39 0.12 40.290.08
HD 120205 120969 55572 168 T7 199 8.35 0.06 0.75 14.30.7
HD 127068 126583 51537 3700 T7 972 8.47 0.18 1.05 18.1870.0001
HD 136655 136643 50492 355 T7 465 8.81 0.02 1.00 constant
HD 138157 138085 51540 3697 T6+7 1159 7.11 0.14 1.10 7.183570.00005 +ell.
HIP 77210 140750 51260 100 T6 49 9.14 0.02 13.70.1
HD 142680 142245 51260 100 T6 64 8.70 0.03 33.41.5
HD 143937 143438 51559 48 T7 57 8.67 0.10 1.16 rotation
HD 143937 0.41 0.914790.00003 eclipsing
HD 147866 147266 51447 728 T6+7 92 8.08 0.03 1.14 80.32.2
Table 6: Summary of photometric data and results. Listed are the comparison (“cmp”) star used for the differential observations, the start date of observations (“HJD start”), the time span of observations () in days, the telescope and photometric bandpasses used (Johnson-Cousins for the T7 APT and Strömgren for the T6 APT), and the number of actual data points , each the mean of three individual readings. The results are summarizes in the subsequent columns and list , the maximum, i.e. least spotted, brightness during our observations; , the largest observed amplitude due to spots and, if eclipsing, due to primary eclipse; C.I., the average color index (-) for T7 observations and/or (-) for T6; , the photometric period and its likely error obtained from a refitting to synthetic data; and a note if applicable.
HD/name HD/cmp HJD start Tel. C.I. Note
star (2,4+) (mag) (mag) (mag) (days)
HD 150202 149843 55572 168 T7 210 7.94 0.05 0.73 36.40.5 1/2
HD 153525 153286 51260 100 T6 53 7.94 0.02 15.40.1
HD 155802 156227 55580 160 T7 149 8.50 0.03 0.85
HD 171067 170651 55602 138 T7 194 7.17 0.02 0.55
HD 184591 183849 51099 T6 263 7.34 0.01 0.62 (48.92.2) uncertain
HD 226099 188149 55634 106 T7 210 7.98 0.05 0.65
HD 190642 189893 51434 3668 T7 791 8.15 0.32 1.26 rotation
HD 190642 0.43 24.83390.0009 eclipsing
HD 197913 198109 51098 51 T6 33 7.13 0.02 6.5560.07
HD 199967 199354 55652 88 T7 160 7.65 0.03 0.40
HD 237944 93470 55569 169 T7 675 9.27 0.07 0.50 5.410.013 rotation
HD 237944 0.25 5.50750.0003 eclipsing
Table 6: (continued)

4.3 Rotational periods and spot amplitudes from photometry

Table 6 is the summary of the results from our photometric analysis. A total of 56 stars out of the total sample of 60 targets were observed, of which 39 have a detectable period. The time coverage and the sampling are very different from target to target, ranging from a minimum of 20 nights for QY Hya (HD 105575) to 4,160 nights (11 yrs) for HY CMa (SAO 151224) with a sampling of all-night-long monitoring (QY Hya) to one observation per night as for most targets. This diversity of data wealth makes a coherent spot-modelling analysis not feasible for the present paper and we just focus on the determination of average light-curve parameters. A more detailed analysis per target is planned for the future whenever feasible (see, e.g. Strassmeier et al. [2011] for the most recent example of HD 123351, excluded from this paper).

Most relevant for this paper is the determination of a precise photometric period, , that can be interpreted as the stellar rotation period. This allows a superior measurement of rotation with respect to spectroscopic measurements because they are independent of the (unknown) inclination of the rotational axis and can be determined much more precisely. To proceed, we first pre-filtered all photometric data by excluding data points with an rms of 0.02 mag in order to remove data grossly affected by clouds. Periods were then searched for either in Johnson or in Strömgren or, for the stars where we have both passbands, in the combined series. For light-curves with a highly harmonic content, the Lomb periodogram (Lomb [1976]) in the formulation of Scargle ([1982]) was applied. In cases where a period could have been affected by the window function, the CLEAN algorithm (Roberts et al. [1987]) was employed to verify, but not to alter, the period identification from the Lomb periodogram. For light curves with a highly non-harmonic content, i.e. for eclipsing binaries, a string-length minimization, a variant of a Lafler-Kinman (Lafler & Kinman [1965]) statistic described in Dworetsky ([1983]), was used to determine the final photometric period. Some of the stars had already had a period determined in our paper I but the period in the present paper supersede these values. In Fig. 4, a phased light curve from all data for each of the variable targets is shown. These light curves are phased with the photometric period indicated in the graph and the respective time of periastron listed in Tables 4 or 5, or ascending node for circular orbits. Single-star zero epochs are arbitrary.

Errors for the periods were obtained by using a method sometimes referred to as “refitting to synthetic data sets” (e.g. Ford [2005]). This method estimates confidence intervals by synthesizing a large number of data sets (typically 10) out from the original data by adding Gaussian random values to the measurements proportional to the actual rms of the data. The respective period-search algorithm is then applied to these synthetic data and the resulting standard deviation assumed to be the standard deviation of the original period. This value is given in Table 6 as the error for .

Note that Table 6 strictly lists photometric periods. We interpret these usually as stellar rotational periods but emphasize that care must be taken because, e.g., in case the star is a close binary, an ellipticity effect could mimic a spot light curve with a photometric period that is easily misinterpreted as the stellar rotation period. For one system, HD 138157, we interpret the 55-mmag amplitude partly due to the ellipticity effect. Its true rotational period is close to the orbital period. For five of our six eclipsing binaries the rotational modulation appears to have the same period as the orbital motion. For one case, HD 190642, a newly discovered eclipsing pair, the spot wave appears doubled humped and gives half of the true rotation period.

The typical error of the magnitude zero point is around 0.01–0.02 mag, but never higher than 0.05 mag. The wave amplitude, , in Table 6 is the maximum observed amplitude within our data coverage. For the eclipsing systems, we cut out the data points during eclipse phases and then redetermined the maximum amplitude. The color index, C.I., is the average color index over all observations. In case of T7 observations it is (-), for T6 it is -, if available. Variations in the C.I. are present but are in general too noisy for period analysis. Most of the observations of HD 136655 had to be discarded due to obvious instrumental problems. Its remaining data shows no evidence for photometric variability. Orbital period and of the eclipsing binary HD 105575 are equally constrainable from photometry than from radial velocities. If =0 is adopted, we obtain =2,454,160.772 and =0.292380.00009 d just from our 20-day long time series. However, because the photometry was obtained around JD2,451,250, i.e. almost 10,000 eclipses prior to the spectroscopic data, the combination of the two data sets still results in a loss of the cycle count and could not be combined. Table 5 gives the orbit computed only with the radial velocities.

4.4 Rotational velocities

Selected spectra of our program stars were subjected to a de-noising procedure based on a principal component analysis developed for Doppler imaging (Carroll et al. [2007], [2009]). This procedure employs typically a total of around 1100 spectral lines in the wavelength range 480–850 nm to determine the noise spectrum. This noise spectrum can then be used to de-noise an arbitrary wavelength section. The only free parameter is the number of principal components. No strict rule can be given for the choice of this value but we followed the prescription laid out in Martínez González et al. ([2008]). It suggests 15 components for our typical late spectral types and wavelength coverage. It is then used to de-noise a well-known and unblended spectral line from which we measure under the assumption of a temperature and gravity dependent macroturbulence. For this paper, we have chosen the well-known and unblended Fe i 549.7516 nm line with an excitation energy of 1.011 eV, a transition probability of , and a typical microturbulence of 2.0 km s. The radial-tangential macroturbulences, , are taken from Gray ([2005]), as listed in Fekel ([1997]). This macroturbulence is then subtracted from the measured total line broadening. At this point, we note that Gray ([2005]) gave most probable macroturbulent velocities, which are 1.414 times greater than the rms values given here. The total line broadening is measured independently from fits with synthetic spectra over a large range of wavelengths (see next section) and the resulting measures were then compared and found to agree within their estimated errors. The final values of and for all our program stars are tabulated in Table 7 for further reference.

Up to three nightly (and two daily) Th-Ar calibration frames are used to monitor the spectrograph focus throughout the year. The line widths of Th-Ar emission lines are determined automatically and an unweighted average stored in the STELLA data base. No focus drifts were evident during the time in question. However, manual refocusing was done after every maintenance run. The telescope focus is being controlled and adjusted daily by inserting a focus pyramid into the telescope beam. It splits a stellar image into four equally distant images if the telescope is in focus (see Granzer et al. [2010]). The STELLA control system issues a message to the operator in Potsdam if this had to be corrected.

Figure 4: Light curves for the stars in Table 6. The time coverage of the observations, , and the photometric period, , are indicated on the top of each panel, both in days. The dots are the or observations from the full epochs given in Table 6. Error bars indicate the standard deviation from three individual measurements. Photometric phase has been computed with the photometric period and the respective time of periastron or ascending node for circular orbits. Single star light curves are plotted with an arbitrary starting time. Note that most of the scatter is due to intrinsic spot changes and not due to instrumental origin. The standard error of a mean was 4–6 mmag for the data and 1.2–3 mmag for the data.
Figure 4: (continued)

4.5 Stellar atmospheric parameters

Five selected spectral orders (#28, 29, 33, 37, 39) from the STELLA/SES spectra are used to determine the stellar effective temperature, the gravity and the metallicity. These orders cover the wavelength ranges 549–556, 560–567, 583–591, 608–616, and 615–623 nm. Our numerical tool PARSES (“PARameters from SES”; Allende-Prieto [2004]) is implemented as a suite of Fortran programs in the STELLA data analysis pipeline. It is based on the synthetic spectrum fitting procedure described in Allende-Prieto et al. ([2006]). Model atmospheres and synthetic spectra were taken from the ATLAS9 CD (Kurucz [1993]). Synthetic spectra are pre-tabulated with metallicities between  dex and +0.5 dex in steps of 0.5 dex, logarithmic gravities between 1.5 and 5 in steps of 0.5, and temperatures between 3500 K and 7,250 K in steps of 250 K for a wavelength range of 380–920 nm. All calculations were done with a microturbulence of 2 km s. This grid is then used to compare with the five selected echelle orders of each spectrum. Free parameters are , , Fe/H, and line broadening , where is the radial-tangential macroturbulence, again adopted from Gray ([2005]) and was fixed during the fit. Internal errors are estimated from the rms of the solutions to the five echelle orders and were for typically 20–30 K, for typically 0.06 dex, and for Fe/H typically 0.03 dex.

Double-lined spectra can not be run automatically through the PARSES routines. We first apply a similar disentangling technique as for the automatic radial-velocity measurement of triple-lined spectra, i.e. we remove once the primary and once the secondary component from the combined spectrum at well-separated phases in order to create a single-star spectrum for each component. The resulting spectra were then subjected to the PARSES synthetic-spectrum fitting. This was done only for the five echelle orders that are employed for the PARSES fit (see above) and not for the entire 80 orders. Errors are generally larger for SB2s than for SB1 and single systems due to continuum cross talk. External errors are again estimated from the rms of the solutions to the five echelle orders and were for typically 100 K, for typically 0.3 dex, and for Fe/H typically 0.3 dex. However, the range of errors is systematically larger for the SB2 systems than for the SB1 and single stars because of the large range of brightness differences between the components in our sample (ranging from 1:1, i.e. nearly equal components, to 12:1 for HIP 999).

Lithium abundances are determined for all individual spectra that had sufficient S/N in the respective echelle order. The time averaged results are listed in Table 7 with respect to the (H) = 12.00 scale for hydrogen. A double Gaussian fit to Li i 6707.8 Å and the nearby Fe i 6707.4-Å line yields an individual equivalent width for the lithium line. Despite that these values are still the combined equivalent width for the close blend from the Li and the Li isotopes, it effectively removes the Fe i blend. Weaker CN features are neglected in this study because of limited S/N and spectral resolution. The listed equivalent widths are the averages of the individual measures with unit weight. The errors in Table 7 are still the O–C error from an individual Gaussian fit but again averaged over all measures in time. Because the rms values of the equivalent widths of an entire time series per star were never larger than 3  of above O–C error, we do not explicitly list them in Table 7. However, these rms are useful to judge eventual long-term variability. SB2’s are measured only at phases of quadrature, where blending is minimized. The curves of growth from Pavlenko & Magazzú ([1996]) are then used to convert the equivalent width to a logarithmic lithium abundance using the non-LTE transformation and the effective temperatures and gravities from Table 7.

Name SB Fe/H (Li)
(mas) (K) (m s) (mÅ) (H = 12.00) (km s)
HD 18645 S 8.71 544530 3.530.04 –0.190.03 144 1.470.15 3 11.00.2
HD 23551 S 5.00 504525 3.040.05 –0.110.02 124 1.030.16 3 6.40.2
HD 24053 S 30.74 560025 4.090.03 –0.010.02 498 2.260.12 3 3
SAO150676 S 575070 4.540.11 –0.160.07 9710 2.710.10 3 23.60.7
HD 43516 S 4.10 512050 2.860.07 –0.150.04 396 1.720.15 3 3
HD 76799 S 6.13 491525 3.260.07 –0.120.03 124 0.860.18 3 7.80.3
HIP46634 S 27.46 514035 4.440.04 –0.010.03 336 1.590.14 2 3
HD 95188 S 27.63 533040 4.390.06 –0.180.03 136 1.290.24 3 6.90.7
HD 95724 S 28.37 496020 4.450.06 +0.060.02 155 0.970.16 2 3
HD 104067 S 48.04 482020 4.370.04 –0.030.02 164 0.830.15 2 8.10.3
HD 108564 S 35.30 456025 4.400.06 –0.900.03 217 0.660.20 2 14.81.4
HD 120205 S 31.78 526030 4.360.05 +0.030.03 105 1.130.18 2 3
HD 136655 S 24.87 501025 4.270.03 +0.090.04 115 0.920.20 3 3
HD 153525 S 57.13 477525 4.470.05 –0.120.03 125 0.660.20 2 3
HD 155802 S 34.27 501015 4.460.04 –0.150.02 134 0.960.13 2 51
HD 171067 S 39.73 552035 4.030.04 –0.150.03 124 1.430.16 3 3
HD 184591 S 4.58 480040 2.820.07 –0.180.03 146 0.800.24 3 4.70.8
HD 218739 S 34.06 567020 4.190.05 –0.070.02 1356 2.800.05 3 7.60.2
HD 40891 32.95 514025 4.370.05 –0.100.02 114 1.030.16 3
HD 62668 4.97 466040 2.920.10 –0.300.04 828 1.600.10 3 211
HD 66553 28.03 527540 4.330.04 +0.090.02 127 1.200.27 2
HD 82159 21.11 515065 4.620.08 –0.130.03 1097 2.220.10 2 12.50.5
HD 82841 4.09 462030 2.940.07 –0.300.03 196 0.740.19 3 8.10.3
HIP 50072 3.15 461539 3.080.08 –0.330.04 226 0.800.21 3 20.80.8
HD 112099 38.12 509520 4.370.04 –0.140.02 114 1.000.16 2 4.10.2
HIP 63322 26.24 499527 4.480.07 –0.230.04 1428 2.190.07 2 61
HIP 63442 3.31 453030 2.850.08 –0.350.04 416 1.070.13 3 22.30.6
HD 138157 5.07 484582 3.240.12 –0.360.06 205 1.030.22 3 401
HD 147866 5.18 458015 2.710.05 –0.240.02 134 0.490.14 3 51
HD 150202 3.75 501025 3.060.07 –0.120.03 255 1.320.16 3 7.80.2
UMi 9.41 521550 3.210.08 –0.250.04 386 1.800.16 3 25.60.2
HD 190642 4.48 476065 2.960.11 –0.470.05 196 0.900.23 3 19.61.0
HD 202109 21.62 491015 2.140.04 –0.080.02 215 1.130.15 3
HD 553 4.74 464590 3.380.36 –0.230.08 224 0.850.22 3 412
5940150 4.400.77 –0.410.26 216 2.070.26 2 27
HIP 999 24.69 528070 4.400.30 –0.310.04 204 1.440.19 2 271
4840150 3.61.2 +0.30.3 158 0.830.42 3 502
HD 8997 43.16 506065 4.530.25 –0.120.04 106 0.910.27 2 3.00.5
452550 4.740.26 +0.020.18 114 0.340.21 3 81
HD 9902 513080 4.00.4 –0.500.16 527 1.850.16 2 121
5715150 3.370.20 –0.380.15 268 1.970.31 5 2.00.5
HD 16884 450050 2.40.4 +0.290.11 317 0.850.20 3 61
453570 3.40.5 –0.260.15 109 0.360.38 3 442
HD 18955 20.56 541080 4.840.10 +0.030.06 92 1.250.13 2 91
5095150 4.80.3 +0.220.17 82 0.900.23 2 51
SAO151224 4595110 3.70.4 –0.180.14 457 1.200.23 3 452
5420105 4.80.3 –0.090.12 226 1.670.25 2 62
HD 45762 3.45 4630100 3.00.7 –0.480.24 315 1.020.22 3 602
6015150 3.51.0 –0.190.18 5 162
HD 50255 30.26 5580100 4.070.12 –0.180.11 456 2.190.18 2 3.01.0
4980150 3.71.0 –1.00.8 94 0.810.30 3 51
Table 7: Determination of astrophysical properties. Column SB denotes the binary component in case the system is SB2 or even SB3 (S means single star, means primary component, secondary component, tertiary component). The parallaxes are from the revised Hipparcos catalog (van Leeuwen [2007]). Effective temperatures, gravities and metallicities are from the STELLA PARSES analysis. Note that errors are mean internal errors from the fits to five spectral orders. The Li abundance is from equivalent-width measures of the Li i 670.8nm line converted with the NLTE calibration of Pavlenko & Magazzú ([1996]) and the temperatures listed here. is the radial-tangential macroturbulence adopted.
Name SB Fe/H
(mas) (K) (m s) (mÅ) (km s)
HD 61994 35.13 5630150 4.130.11 +0.030.12 174 1.690.23 2 41
4775150 4.60.6 –0.270.33 94 0.560.33 3 91
HD 73512 39.28 5110115 4.580.12 –0.250.04 115 1.000.17 2 51
4600130 4.40.5 –0.370.17 113 0.410.27 3 51
HD 82286 9.57 480040 3.730.31 –0.050.09 215 1.000.17 3 37.51.5
4785150 3.920.35 –0.420.20 246 1.040.32 3 40.52
HD 93915 22.78 5520105 4.280.24 –0.290.09 124 1.430.22 2 51
5315120 4.250.24 –0.220.09 93 1.170.22 2 31
HD 95559 18.43 5090110 4.470.27 –0.100.12 166 1.140.28 2 332
5065150 4.560.33 +0.070.12 206 1.230.32 2 332
HD 105575 19.77 5650150 4.730.11 –0.460.08 142 1.610.17 2 4215
HD 106855 22.88 4750110 4.480.33 –0.870.19 224 0.910.24 2 302
4950150 4.00.8 –0.50.4 114 0.850.30 3 52
HD 109011 42.13 503075 4.590.27 –0.170.10 305 1.420.19 2 51
4900150 3.71.0 +0.20.3 135 0.840.33 3 61
HD 111487 5500150 4.470.28 –0.360.11 134 1.450.26 2 422
4700150 4.60.5 –0.10.5 146 0.640.38 3 282
HD 112859 5.24 4780120 3.410.38 –0.240.15 477 1.450.23 3 201
6150150 2.50.5 +0.050.3 5 51
HD 127068 9.75 4850135 3.610.27 –0.480.07 765 1.790.19 3 61
5560150 3.90.8 –0.390.14 105 1.460.31 3 82
HIP 77210 20.73 5190120 4.410.26 –0.430.10 144 1.180.25 2 31
4720150 4.740.31 +0.080.11 165 0.730.33 3 51
HD 142680 28.23 4885110 4.350.26 –0.220.05 53 0.540.24 3 31
4500150 4.60.6 –0.510.36 83 0.210.29 3 51
HD 143937 23.73 5160140 4.480.16 –0.300.13 126 1.110.33 2 552
4730150 4.720.17 –0.010.13 136 0.650.35 3 452
HD 197913 176 5520100 4.18<