A Library of Isochrones with Hyades-based Empirical Corrections

The isochrones here are based on the one described in Pinsonneault et al. 2004, "The Distances to Open Clusters as Derived from Main-Sequence Fitting. II. Construction of Empirically Calibrated Isochrones," ApJ, 600, 946.

The production of these isochrones and tests of their accuracy are presented in An et al. 2006, "The Distances to Open Clusters as Derived from Main-sequence Fitting.  III.  Improved Accuracy with Empirically Calibrated Isochrones," ApJ, submitted (astro-ph/0607549).  Please cite this paper if you use the isochrones on this page.

As described in Paper II, we began with the latest YREC evolutionary tracks (Sills, Pinsonneault & Terndrup 2000), and generated an isochrone at [Fe/H] = +0.13, the Hyades metallicity from Paulson, Sneden, & Cochran (2003).  Then we generated corrections to the isochrone colors to better match photometry in the Hyades.

In the table below, we present this empirical Hyades isochrone and YREC isochrones with various color-temperature relations.  Paper III also corrects the V - I (Cousins) colors of the isochrones to fix a small error in Paper II in the transformation from the Johnson to the Cousins systems.  Isochrones with and without this correction are tabulated below.

In the first three rows of the table, we provide isochrones with the Alonso et al. (1995, 1996) and the Lejeune et al (1998) color corrections.  There are small, systematic differences between the computed colors and the photometry in the Hyades.

The isochrones consist of ASCII tables with 11 columns:

  1. Mass in solar masses
  2. Effective temperature (Kelvins)
  3. Log(10) luminosity in solar units
  4. Log g (cgs)
  5. Bolometric luminosity (magnitudes)
  6. Absolute visual magnitude
  7. B-V color
  8. V-I (Cousins) color
  9. V-K color;  K is on the 2MASS system
  10. J-K color
  11. H-K color;  this and J-K are not accurately calibrated on the Hyades and so are approximate

There are 36 ages in each table, from 20 Myr to 4 Gyr.   Masses can range from 0.25 Msun to 8 Msun, whether or not such stars exist at the given age.  Different isochrone sets use different mass grids. 

Missing or invalid entries are listed as -99.0.

The solar metallicity is taken as Z = 0.01757.

The filenames in the table below are shortened somewhat from their actual filenames on the web site, in order to keep the table from getting too wide.

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Description [Fe/H] = -0.3 -0.2 -0.1 0.0 +0.1 +0.2
Isochrones with Alonso et al. (1995, 1996) color-temperature relation al00904.txt al01130.txt al01410.txt al01757.txt al02180.txt al02700.txt
with Lejeune et al. (1998) before their empirical corrections to the color-temperature relation lj98-00904.txt lj98-01130.txt lj98-01410.txt lj98-01757.txt lj98-02180.txt lj98-02700.txt
with Lejeune et al. (1998) after their empirical corrections to the color-temperature relation lj98c00904.txt lj98c01130.txt lj98c01410.txt lj98c01757.txt lj98c02180.txt lj98c02700.txt
isochrones in the previous row, with additional color shifts to match the Hyades photometry at [Fe/H] = +0.13 lj98e00904.txt lj98e01130.txt lj98e01410.txt lj98e01757.txt lj98e02180.txt lj98e02700.txt
isochrones in the previous row, with the additional correction in V-I, which improves the transformation from the Johnson system. lj98a00904.txt lj98a01130.txt lj98a01410.txt lj98a01757.txt lj98a02180.txt lj98a02700.txt

Web site authors: Donald Terndrup, Deokkeun An, Marc Pinsonneault,  Ben Sostrom.  See the citation information on the main YREC page.

References:

Alonso, A., Arribas, S., & Martínez-Roger, C. 1995, A&A, 297, 197
Alonso, A., Arribas, S., & Martínez-Roger, C. 1996, A&AS, 117, 227
Lejeune, T., Cuisinier, F., & Buser, R. 1998, A&AS, 130, 65
Paulson, D. B., Sneden, C., & Cochran, D. W. 2003, AJ, 125, 3185
Sills, A., Pinsonneault, M. H., & Terndrup, D. 2000, ApJ, 534, 335 

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Last modified:  August 9, 2006 (dmt)