The HIPPARCOS Hertzsprung-Russell diagram of S stars: Probing nucleosynthesis and dredge-up
| dc.creator | Van Eck, S. | |
| dc.creator | Jorissen, A. | |
| dc.creator | Udry, S. | |
| dc.creator | Mayor, M. | |
| dc.creator | Pernier, B. | |
| dc.date | 1997-08-01 | |
| dc.date.accessioned | 2026-07-07T02:23:56Z | |
| dc.date.available | 2026-07-07T02:23:56Z | |
| dc.description | HIPPARCOS trigonometrical parallaxes make it possible to compare the location of Tc-rich and Tc-poor S stars in the Hertzsprung-Russell (HR) diagram: Tc-rich S stars are found to be cooler and intrinsically brighter than Tc-poor S stars. The comparison with the Geneva evolutionary tracks reveals that the line marking the onset of thermal pulses on the asymptotic giant branch (AGB) matches well the observed limit between Tc-poor and Tc-rich S stars. Tc-rich S stars are, as expected, identified with thermally-pulsing AGB stars of low and intermediate masses, whereas Tc-poor S stars comprise mostly low-mass stars (with the exception of 57 Peg) located either on the red giant branch or on the early AGB. Like barium stars, Tc-poor S stars are known to belong exclusively to binary systems, and their location in the HR diagram is consistent with the average mass of 1.6 +- 0.2 Msun derived from their orbital mass-function distribution. A comparison with the S stars identified in the Magellanic Clouds and in the Fornax dwarf elliptical galaxy reveals that they have luminosities similar to the galactic Tc-rich S stars. However, most of the surveys of S stars in the external systems did not reach the lower luminosities at which galactic Tc-poor S stars are found. The deep Westerlund survey of carbon stars in the SMC uncovered a family of faint carbon stars that may be the analogues of the low-luminosity, galactic Tc-poor S stars. | |
| dc.description | 16 pages, 10 figures, Latex, accepted for publication in Astronomy and Astrophysics main journal. Also available at http://astro.ulb.ac.be/iaa.htm | |
| dc.identifier | https://arxiv.org/abs/astro-ph/9708006 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/9708006 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/11441 | |
| dc.subject | Astrophysics | |
| dc.title | The HIPPARCOS Hertzsprung-Russell diagram of S stars: Probing nucleosynthesis and dredge-up | |
| dc.type | text |