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Near-infrared observations of candidate extrinsic S stars
Photometric observations in the near infrared for 161 S stars, including18 Tc-rich (intrinsic) stars, 19 Tc-deficient (extrinsic) ones and 124candidates for Tc-deficient S stars, are presented in this paper. Basedon some further investigations into the infrared properties of bothTc-rich and Tc-deficient S stars, 104 candidates are identified as verylikely Tc-deficient S stars. The large number of infrared-selectedTc-deficient S stars provides a convenient way to study the physicalproperties and the evolutionary status of this species of S stars.
| Beobachtungsergebnisse Bundesdeutsche Arbeitsgemeinschaft fur Veraenderliche Sterne e.V.
Not Available
| Aufsuchkarten fur intrinsic Variable Stars in Brno.
Not Available
| A CORAVEL radial-velocity monitoring of giant BA and S stars: Spectroscopic orbits and intrinsic variations. I.
With the aim of deriving the binary frequency among Ba and S stars, 56new spectroscopic orbits (46 and 10, respectively) have been derived forthese chemically-peculiar red giants monitored with the \coravel\spectrometers. These orbits are presented in this paper (38 orbits) andin a companion paper \cite[(Udry et al. 1998,]{Udry} Paper II; 18orbits). The results for 12 additional long-period binary stars (6 and6, respectively), for which only minimum periods (generally exceeding 10y) can be derived, are also presented here (10) and in Paper II (2). Theglobal analysis of this material, with a few supplementary orbits fromthe literature, is presented in \cite[Jorissen et al.(1998).]{Jorissen98} For the subsample of Mira S, SC and (Tc-poor) Cstars showing intrinsic radial-velocity variations due to atmosphericphenomena, orbital solutions (when available) have been retained if thevelocity and photometric periods are different (3 stars). However, it isemphasized that these orbit determinations are still tentative. Threestars have been found with radial-velocity variations synchronous withthe light variations. Pseudo-orbital solutions have been derived forthose stars. In the case of RZ Peg, a line-doubling phenomenon isobserved near maximum light, and probably reflects the shock wavepropagating through the photosphere. Based on observations obtained atthe Haute-Provence Observatory (France) and at the European SouthernObservatory (ESO, La Silla, Chile).
| Insights into the formation of barium and Tc-poor S stars from an extended sample of orbital elements
The set of orbital elements available for chemically-peculiar red giant(PRG) stars has been considerably enlarged thanks to a decade-longCORAVEL radial-velocity monitoring of about 70 barium stars and 50 Sstars. When account is made for the detection biases, the observedbinary frequency among strong barium stars, mild barium stars andTc-poor S stars (respectively 35/37, 34/40 and 24/28) is compatible withthe hypothesis that they are all members of binary systems. Thesimilarity between the orbital-period, eccentricity and mass-functiondistributions of Tc-poor S stars and barium stars confirms that Tc-poorS stars are the cooler analogs of barium stars. A comparative analysisof the orbital elements of the various families of PRG stars, and of asample of chemically-normal, binary giants in open clusters, revealsseveral interesting features. The eccentricity - period diagram of PRGstars clearly bears the signature of dissipative processes associatedwith mass transfer, since the maximum eccentricity observed at a givenorbital period is much smaller than in the comparison sample of normalgiants. be held The mass function distribution is compatible with theunseen companion being a white dwarf (WD). This lends support to thescenario of formation of the PRG star by accretion of heavy-element-richmatter transferred from the former asymptotic giant branch progenitor ofthe current WD. Assuming that the WD companion has a mass in the range0.60+/-0.04 Msb ȯ, the masses of mild and strong barium starsamount to 1.9+/-0.2 and 1.5+/-0.2 Msb ȯ, respectively. Mild bariumstars are not restricted to long-period systems, contrarily to what isexpected if the smaller accretion efficiency in wider systems were thedominant factor controlling the pollution level of the PRG star. Theseresults suggest that the difference between mild and strong barium starsis mainly one of galactic population rather than of orbital separation,in agreement with their respective kinematical properties. There areindications that metallicity may be the parameter blurring the period -Ba-anomaly correlation: at a given orbital period, increasing levels ofheavy-element overabundances are found in mild barium stars, strongbarium stars, and Pop.II CH stars, corresponding to a sequence ofincreasingly older, i.e., more metal-deficient, populations. PRG starsthus seem to be produced more efficiently in low-metallicitypopulations. Conversely, normal giants in barium-like binary systems mayexist in more metal-rich populations. HD 160538 (DR Dra) may be such anexample, and its very existence indicates at least that binarity is nota sufficient condition to produce a PRG star. This paper is dedicated tothe memory of Antoine Duquennoy, who contributed many among theobservations used in this study
| Proper motions, absolute magnitudes and spatial distribution of zirconium stars.
Not Available
| A catalogue of associations between IRAS sources and S stars.
Cross identifications between the General Catalogue of Galactic S Stars(GCGSS), the IRAS Point Source Catalogue (PSC), and the Guide StarCatalogue (GSC) are presented. The purpose of the present catalogue isi) to provide a clean sample of S stars with far-IR data, and ii) toprovide accurate GSC positions for S stars, superseding those listed inthe GCGSS. The IRAS colour-colour diagram and the galactic distributionof S stars associated with an IRAS source are presented. Several S starshaving extended images in at least one IRAS band have also beenidentified.
| S stars: infrared colors, technetium, and binarity
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&A...271..463J&db_key=AST
| The 71st Name-List of Variable Stars
Not Available
| Photographic Observations of Five DHK Variables
Not Available
| Eight New or Undesignated Variable Stars
Not Available
| Infrared Spectra and Circumstellar Emission of Late-Type Stars. III. S-Type Stars
Near-infrared photometry was carried out at the J, H, K, and L bands for73 S-type stars. The statistical characteristics of the infrared spectraand the circumstellar emission of S-type stars were examined usingnear-infrared photometric data, IRAS photometric data, and thelow-resolution spectra obtained by IRAS. The characteristics of thephotometric spectra of S-type stars were compared with those ofoxygen-rich stars and carbon stars. We found that MS and SC stars haveinfrared spectral characteristics similar to those of both oxygen-richstars and carbon stars, respectively. However, mild S, medium S, andstrong S stars were found to have a variety of spectral characteristicsin the infrared region. Correlations between the 10-mu m spectralfeatures and infrared photometric spectra were examined. It was foundthat S-type stars show a variety of spectral characteristics regardingboth the 10-mu m spectral feature and photometric spectra.
| A General Catalogue of Galactic S-Stars - ED.2
Not Available
| A Search for S-Stars in the IRC and AFGL Catalogues
Seventeen unidentified sources contained in the 2jt JR Catalogue, andAFGL-AFGLS Catalogues have been tentatively indicated as S stars from acomparison with the General Catalogue of S stars. An analysis based onthe I - K and K - [4.2j.~] behavior has been performed for all thesources which have been found to be in common with all the abovementioned catalogues. The results lead to the conclusion that thepresence of circumstellar shells seems to be very unlike for theseobjects in spite of their evolutionary status which is intermediatebetween M and C type stars
| A general catalogue of S stars.
Not Available
| A list of additionnal variable stars in the two-micron Sky survey.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973AJ.....78..471L&db_key=AST
| Catalogue d'étoiles variables nouvelles
Not Available
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Стрела |
| Прямое восхождение: | 20h14m20.56s |
| Склонение: | +17°00'54.7" |
| Видимая звёздная величина: | 9.072 |
| Собственное движение RA: | 25.2 |
| Собственное движение Dec: | 4 |
| B-T magnitude: | 11.261 |
| V-T magnitude: | 9.253 |
Каталоги и обозначения:
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