Stellar and circumstellar evolution of long period variable stars
Abstract
In a first paper, HIPPARCOS astrometric and kinematic data were used to calibrate both infrared K and IRAS luminosities at the same time as kinematic parameters of Long Period Variable stars (LPVs). Individual estimated absolute magnitudes and a probabilistic assignation to galactic populations were deduced from these calibrations for each LPV of our sample. Here we propose a scenario of simultaneous stellar and circumstellar evolution according to the galactic populations. The transitory states of S and Tc stars allow us to confirm the location of the first dredge-up at Mbol=-3.5. There is also evidence suggesting that a previous enrichment in s-elements from a more evolved companion may accelerate the evolution along the AGB. The possible evolution to OH LPVs is included in this scenario, and any of these stars may have a mass at the limit of the capability for a C enrichment up to C/O > 1. A list of bright massive LPVs with peculiar envelope and luminosity properties is proposed as Hot Bottom Burning candidates. The He-shell flash star, R Cen, is found to be exceptionally bright and could become, before leaving the AGB, a C-rich LPV brighter than the usual luminosity limit of carbon stars.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 2001
- DOI:
- 10.1051/0004-6361:20011392
- arXiv:
- arXiv:astro-ph/0110268
- Bibcode:
- 2001A&A...380..198M
- Keywords:
-
- STARS: VARIABLE: GENERAL;
- STARS: EVOLUTION;
- STARS: AGB AND POST-AGB;
- Astrophysics
- E-Print:
- Accepted for publication in Astronomy &