Given a location in the HR diagram, this program allows you to determine the stellar parameters associated with this point. To proceed, select the metallicity and then enter the color and magnitude of the observational data. You are also able to simulate observational uncertainties. The results will be displayed on the screen and can be saved by typing Alt + S. They include the stellar mass, age, radius, luminosity, effective temperature. By default the program will give you the mass, radius and age of the star assuming it is on its pre-main sequence track.

If you use colors and magnitudes, the data are converted in the different bands using either the conversion table from Kenyon and Hartmann (1995, AJSS 101, 117) or the one compiled by Siess et al. (1997, A&A 324, 556). Note that in the latter case, only the B,V,R and I magnitudes are available. The colors are expressed in the Cousins system.
Reference to be mentioned:
Siess L., Dufour E., Forestini M. 2000, A&A, 358, 593 PDF


Z = 0.04 Z = 0.03 Z = 0.02 Z = 0.02+over Z = 0.01

Observational data


Observational uncertainties

Simulate observational uncertainties yes no

  • Uncertainty associated to the x coordinate
  • Uncertainty associated to the y coordinate

This procedure assumes that x and y have values ranging between $x\pm dx$ and $y\pm dy$


Additional information wanted yes no

  • surface abundances of light elements (He, Li, Be, B)
  • central conditions (central temperature, density, degeneracy)
  • internal structure (size, mass of the burning region, convective envelope, moments of inertia)
  • energetics (luminosity associated to nuclear/gravothermal sources)

Conversion Table

Siess et al. (1997) Kenyon and Hartmann (1995)

Please note

  • if you want information in the K, J, H or L band you MUST use the Kenyon and Hartmann (1995) compilation.
  • the Siess et al. (1997) conversion table only provides the B, V, R and I magnitudes.