Spectroscopic criteria for luminosity calibration of massive B5-A5 stars
Abstract
White massive stars are very luminous. Their potential to serve as standard candles for extragalactic distance measurement as well as tracers of chemical evolution of galaxies remains partially unfulfilled. Only about 50 of the brightest Galactic objects of this group have been comprehensively studied and even fewer have well-constrained fundamental parameters. Although there are many spectroscopic/photometric methods to determine stellar effective temperature, the luminosity determination remains uncertain. Some luminosity criteria proposed in the past have not been sufficiently explored, while others are affected by circumstellar matter that becomes significant for stars with masses over 15 Msun. In order to investigate both temperature and luminosity criteria, we have obtained optical spectra of nearly 100 stars classified as B5-A5 supergiants and bright giants, including over 30 members of clusters and associations. Using spectra with a resolving power between 10000 and 60000 measured over 20 absorption lines, studied their correlations with the fundamental parameters, and refined classification of nearly a dozen objects. The best quantitative classification criteria are presented and discussed.
- Publication:
-
Massive Stars: From alpha to Omega
- Pub Date:
- June 2013
- Bibcode:
- 2013msao.confE.169M