1997 RELEASE BY F.D'ANTONA AND I.MAZZITELLI

Reference papers:

Presentation of the isochrones:

F.D'Antona and I. Mazzitelli, 1997, `Evolution of low mass stars' in ``Cool stars in Clusters and Associations'', eds. R. Pallavicini \& G. Micela, Mem.S.A.It., 68, n.4

Problems concerning the treatment of convection in low mass stars:

F. D'Antona, I. Mazzitelli 1998, `A role for superadiabatic convection in low mass structures?', in ``Brown Dwarfs and Extrasolar Planets", ASP Conference Series, eds. R. Rebolo, E. Martin, M.R. Zapatero Osorio, in press

Reasons why we adopt several initial Deuterium abundances:

Censori, C. & D'Antona, F. 1998, `Brown Dwarfs and the luminosity function of young stellar populations", in ``Brown Dwarfs and Extrasolar Planets" ASP Conference Series, eds. R. Rebolo, E. Martin, M.R. Zapatero Osorio, in press

We provide two sets of abundances: (Z=0.02, Y=0.28) and (Z=0.01, Y=0.26). We give three different deuterium abundances for Z=0.02 (mass fraction X_D=1, 2 and 4 10^-5) and two abundances for Z=0.01 (X_D=2 and 4 10^-5).

The tracks are contained in the files

hrZZZ.dDD : where ZZZ=001 or 002 represents the Z value, and DD= 15, 25 or 45 represents the X_D abundance

the isochrones are in the files

isoZZDD.tot : where ZZ=01 or 02 represents the Z value, and DD=15, 25 or 45 is the ZX_D abundance

Ages are given from &e4yr at least up to 10^8yr. Generally also up to 5 10^8yr. The presentation paper in the Mem. S.A.It. also suggests possible renormalizations of the isochrones for very low ages.

In total we have the following files:

hr001.d25 iso0125.tot

hr001.d45 iso0145.tot

hr002.d15 iso0215.tot

hr002.d25 iso0225.tot

hr002.d45 iso0245.tot

Several quantities are provided in the tracks files (apart from the anomalous hr002.d15, which contains only age, logL/Lsun and Teff) Notice that column 9 contains the logarithm of the deuterium abundance, and then the logarithm of the lithium abundance. This latter quantity has not been computed below log X_Li=-12: so the values below -12 indicate mostly total depletion.

As it was recommended in the MEMO file accompanying the 1994 release of pre main sequence evolution, we warn researchers to use these new tracks mainly as guidelines in a still difficult field. There have been several changes in the input physics, mainly in the equation of state, opacities and convection treatment. For this latter, the main differences occurr in the difficult mass range below about 0.3Msun (the new tracks are cooler than the 1994 tracks by 100-150K), in the main sequence AND in the premain sequence.