## Appendix A: interpolation of ages and masses among SEMSuppose that the effective temperature (),
surface gravity () and metallicity
() of a star are known parameters. As described
in Sect. 2, we can then determine a new set of SEM at
. Let ,
, and
be the log ,
, age and mass, respectively, of the
As a first approximation, it can be assumed that log
, ,
and vary linearly with
inside a given EEP ( We also assume that log , , and vary linearly with the age between two EEP points inside a given track. The log and of our star can then be calculated as being the interpolation factor along an evolutionary track Equations (A6) and (A1) allow us to express the interpolation factor as Introducing (A2) and (A10) in (A7), we obtain a second degree equation in whose coefficients are given by and Since and Once is known, Eq. (A5) allows us to determine the initial mass of our star and, from Eqs. (A4) and (A8), its current mass. Finally, the age is determined by means of Eqs. (A3), (A5) and (A9). ## Appendix B: ages, masses and weighting factors in the Overlap RegionMean ages and masses have been calculated for stars placed in the Overlap Region following expressions 1. Typical differences between computed values and those we would assign if evolutionary phases were known are shown in Table 2 as a function of the position in the HR diagram.
© European Southern Observatory (ESO) 1997 Online publication: June 30, 1998 |