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11. General Catalogue of S Stars
ID:
ivo://CDS.VizieR/III/60
Title:
General Catalogue of S Stars
Short Name:
III/60
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalog is intended to list all S stars having known positions of at least roughly the precision of the Henry Draper Catalogue. An S star is a star in whose spectrum the bands of the ZrO molecule are detectable, ordinarily without needing sufficient spectral resolution to resolve the individual rotational lines of a band in its stronger parts. The majority of the stars in the catalog were classified on the basis of the band with a head near 6474 Angstroms, in the red system of ZrO. The catalog contains right ascension and declination (B1900.0), photographic, visual, or infrared magnitudes, spectral types, and designations that give the star's occurrence in various finding lists, including an unpublished one.
12. Infrared photometry of mass-losing AGB stars
ID:
ivo://CDS.VizieR/J/A+A/488/675
Title:
Infrared photometry of mass-losing AGB stars
Short Name:
J/A+A/488/675
Date:
21 Oct 2021
Publisher:
CDS
Description:
Asymptotic giant branch (AGB) phases mark the end of the evolution for low- and intermediate-mass stars. Our understanding of the mechanisms through which they eject the envelope and our assessment of their contribution to the mass return to the interstellar medium and to the chemical evolution of Galaxies are hampered by poor knowledge of their luminosities and mass loss rates, both for C-rich and for O-rich sources. We plan to establish criteria permitting a more quantitative determination of luminosities (and subsequently of mass loss rates) for the various types of AGB stars on the basis of infrared fluxes. In this paper, in particular, we concentrate on O-rich and s-element-rich MS, S stars and include a small sample of SC stars. We reanalyze the absolute bolometric magnitudes and colors of MS, S, SC stars on the basis of a sample of intrinsic (single) and extrinsic (binary) long period variables. We derive bolometric corrections as a function of near- and mid-infrared colors, adopting as references a group of stars for which the spectral energy distribution could be reconstructed in detail over a large wavelength range. We determine the absolute HR diagrams, and compare luminosities and colors of S-type giants with those, previously derived, of C-rich AGB stars. Luminosity estimates are also verified on the basis of existing period-luminosity relations valid for O-rich Miras. S star bolometric luminosities are almost indistinguishable from those of C-rich AGB stars. On the contrary, their circumstellar envelopes are thinner and less opaque. Despite this last property the IR wavelengths remain dominant, with the bluest stars having their maximum emission in the H or K(short) bands. Near-to-mid infrared color differences are in any case smaller than for C stars. Based on period-luminosity relations for O-rich Miras and on Magnitude-color relations for the same variables we show how approximate distances (hence intrinsic parameters) for sources of so far unknown parallax can be inferred. We argue that most of the sources have a rather small mass (<2M_{sun}_); dredge-up might then be not effective enough to let the C/O ratio exceed unity.
13. IRAS flux densities of S stars
ID:
ivo://CDS.VizieR/J/A+AS/129/363
Title:
IRAS flux densities of S stars
Short Name:
J/A+AS/129/363
Date:
21 Oct 2021
Publisher:
CDS
Description:
It is the purpose of this paper to rediscuss the circumstellar properties of S stars and to put these properties in perspective with our current understanding of the evolutionary status of S stars, in particular the intrinsic/extrinsic dichotomy. This dichotomy states that only Tc-rich ("intrinsic") S stars are genuine thermally-pulsing asymptotic giant branch stars, possibly involved in the M-S-C evolutionary sequence. Tc-poor S stars are referred to as "extrinsic" S stars, because they are the cooler analogs of barium stars, and like them, owe their chemical peculiarities to mass transfer across their binary system. Accordingly, an extensive data set probing the circumstellar environment of S stars (IRAS flux densities, maser emission, CO rotational lines) has been collected and critically evaluated. This data set combines new observations (9 stars have been observed in the CO J=2-1 line and 3 in the CO J=3-2 line, with four new detections) with existing material (all CO and maser observations of S stars published in the literature). The IRAS flux densities of S stars have been re-evaluated by co-adding the individual scans, in order to better handle the intrinsic variability of these stars in the IRAS bands, and possible contamination by Galactic cirrus.
14. IR observations of S stars
ID:
ivo://CDS.VizieR/J/A+A/387/129
Title:
IR observations of S stars
Short Name:
J/A+A/387/129
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometric observations in the near infrared for 161 S stars, including 18 Tc-rich (intrinsic) stars, 19 Tc-deficient (extrinsic) ones and 124 candidates for Tc-deficient S stars, are presented in this paper. Based on some further investigations into the infrared properties of both Tc-rich and Tc-deficient S stars, 104 candidates are identified as very likely Tc-deficient S stars. The large number of infrared-selected Tc-deficient S stars provides a convenient way to study the physical properties and the evolutionary status of this species of S stars.
15. Spectrophotometry of S and carbon stars
ID:
ivo://CDS.VizieR/J/AZh/76/604
Title:
Spectrophotometry of S and carbon stars
Short Name:
J/AZh/76/604
Date:
21 Oct 2021
Publisher:
CDS
Description:
The absolute energy distributions in the visual spectra (3200-7600{AA}) of 13 N carbon stars and three S stars have been investigated. The spectral resolution of the data is 50 A and the relative rms error is 2-5%. The data supplement and extend the Almaty and other spectrophotometric catalogs that are lacking in these types of objects.
16. Spitzer/IRS analysis of the 30-micron sources
ID:
ivo://CDS.VizieR/J/A+A/626/A92
Title:
Spitzer/IRS analysis of the 30-micron sources
Short Name:
J/A+A/626/A92
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis and comparison of the 30{mu}m dust features seen in the Spitzer Space Telescope spectra of 207 carbon-rich asymptotic giant branch (AGB) stars, post-AGB objects, and planetary nebulae (PNe) located in the Milky Way, the Magellanic Clouds (MCs), or the Sagittarius dwarf spheroidal galaxy (Sgr dSph), which are characterised by different average metallicities. We investigated whether the formation of the 30{mu}m feature carrier may be a function of the metallicity. Through this study we expect to better understand the late stages of stellar evolution of carbon-rich stars in these galaxies. Our analysis uses the "Manchester method" as a basis for estimating the temperature of dust for the carbon-rich AGB stars and the PNe in our sample. For post-AGB objects we changed the wavelength ranges used for temperature estimation, because of the presence of the 21{mu}m feature on the short wavelength edge of the 30{mu}m feature. We used a black-body function with a single temperature deduced from the Manchester method or its modification to approximate the continuum under the 30{mu}m feature. We find that the strength of the 30{mu}m feature increases until dust temperature drops below 400K. Below this temperature, the large loss of mass and probably the self-absorption effect reduces the strength of the feature. During the post-AGB phase, when the intense mass-loss has terminated, the optical depth of the circumstellar envelope is smaller, and the 30{um}m feature becomes visible again, showing variety of values for post-AGB objects and PNe, and being comparable with the strengths of AGB stars. In addition, the AGB stars and post-AGB objects show similar values of central wavelengths - usually between 28.5 and 29.5{mu}m. However, in case of PNe the shift of the central wavelength towards longer wavelengths is visible. The normalised median profiles for AGB stars look uniformly for various ranges of dust temperature, and different galaxies. We analysed the profiles of post-AGB objects and PNe only within one dust temperature range (below 200K), and they were also similar in different galaxies. In the spectra of 17 PNe and five post-AGB objects we found the broad 16-24{mu}m feature. Two objects among the PNe group are the new detections: SMP LMC 51, and SMP LMC 79, whereas in the case of post-AGBs the new detections are: IRAS 05370-7019, IRAS 05537-7015, and IRAS 21546+4721. In addition, in the spectra of nine PNe we found the new detections of 16-18{mu}m feature. We also find that the Galactic post-AGB object IRAS 11339-6004 has a 21{mu}m emission. Finally, we have produced online catalogues of photometric data and Spitzer IRS spectra for all objects that show the 30{mu}m feature. These resources are available online for use by the community. The most important conclusion of our work is the fact that the formation of the 30{mu}m feature is affected by metallicity. Specifically that, as opposed to more metal-poor samples of AGB stars in the MCs, the feature is seen at lower mass-loss rates, higher temperatures, and has seen to be more prominent in Galactic carbon stars. The averaged feature (profile) in the AGB, post-AGB objects, and PNe seems unaffected by metallicity at least between a fifth and solar metallicity, but in the case of PNe it is shifted to significantly longer wavelengths.

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