Theoretical zero age main sequences revisited
V. Castellani 1,
S. Degl'Innocenti 1,2 and
M. Marconi 3
Received 7 December 1998 / Accepted 22 July 1999
Zero Age Main Sequence (ZAMS) models with updated physical inputs are presented for selected assumptions about the chemical composition, covering the ranges 0.6 M 1.2 , 0.0001 Z 0.04, 0.23 Y 0.34. The HR diagram location of the ZAMS as a function of Y and Z is discussed both in the theoretical (logL, logTeff) and in the observational (Mv, B-V) diagrams, showing that the V magnitude presents an increased dependence on Z to be taken into account when discussing observational evidences. Analytical relations quantifying both these dependences are derived. Implications for the galactic helium to heavier elements enrichment Y/Z are finally discussed.
Key words: stars: general stars: Hertzsprung Russel (HR) and C-M diagrams
Send offprint requests to: S. Degl'Innocenti, Dipartimento di Fisica Università di Pisa, piazza Torricelli 2, I-56126 Pisa, Italy (email@example.com)
This article contains no SIMBAD objects.
© European Southern Observatory (ESO) 1999
Online publication: September 13, 1999