A Library of Isochrones with (Pleiades+Hyades)-based Empirical Corrections

• Version 1.0:  June 4, 2007
  

The isochrones on this page are described in An, Terndrup, & Pinsonneault. 2007, "The Distances to Open Clusters from Main-sequence Fitting.  IV.  Cepheid Period-Luminosity Relations," ApJ, submitted.  Please cite this paper if you use the data on this page.

Theorectical isochrones were generated from the latest YREC evolutionary tracks ( Sills, Pinsonneault, & Terndrup 2000) and are the same as those used for the Hyades-based calibration.  To extend the calibration toward higher stellar masses, we used the Pleiades at the distance modulus of (m - M)₀ = 5.632 (133.8 pc) and [Fe/H] = +0.04 (see references in Paper III)  and derived empirical color-T_eff corrections on broadband colors from Lejeune et al. (1998) color tables.

The empirical Pleiades isochrone and color corrections are given in the file pleiadesiso.txt.   The color corrections are defined by the empirical Pleiades isochrone less theoretical isochrone colors at fixed T_eff or M_V. The photometric data used to calibrate the isochrone is given in the file pleiadesphot.txt. 

These color adjustments were made to isochrones with several metallicities above T_eff = 6500 K.   The Hyades-based corrections remain unchanged below this temperature.   In the table below are empirically calibrated isochrones based on non-convective core overshoot models.  We took the solar metallicity of Z = 0.01757 with the initial solar chemical mixture from Grevesse & Noels (1993) for all of the models (see Paper I for detailed information).

[M/H]	-0.3	-0.2	-0.1	0.0	+0.1	+0.2
Isochrones	lj98m00904.txt	lj98m01130.txt	lj98m01410.txt	lj98m01757.txt	lj98m02180.txt	lj98m02700.txt

Each file contains isochrones with 36 different ages from 20 Myr to 4 Gyr, and different stellar masses from 0.2 M_sun to 8 M_sun.  Missing or invalid entries are listed as -99.0.  The columns are:

1. Mass (solar units)
2. Effective temperature (Kelvins)
3. Log(10) luminosity (solar units)
4. Log(10) surface gravity (cgs)
5. Bolometric luminosity (mag)
6. Absolute magnitude in V (mag)
7. B - V color (mag)
8. V - I_C (Cousins) color (mag)
9. V - K_s color (mag);  K_s is on the 2MASS system
10. J - K_s (2MASS) color (mag)
11. H - K_s (2MASS) color (mag);  this is not calibrated on the Pleiades and so are approximate

References:

Grevesse, N., & Noels, A. 1993, in Origin and Evolution of the Elements, ed. M. Prantzos, E. Vangioni-Flam, & M. Cassé (Cambridge: Cambridge Univ. Press), 15
Hertzsprung, E. 1947, Annalen van de Sterrewacht te Leiden, 19, 1
Lejeune, T., Cuisinier, F., & Buser, R. 1998, A&AS, 130, 65
Sills, A., Pinsonneault, M. H., & Terndrup, D. 2000, ApJ, 534, 335
Trumpler, R. J. 1921, Lick Observatory Bulletin, 10, 110 

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Last modified:  June 4, 2007 (dmt)