Miscellanea Color-Temperature Empirical Calibrations

A certain numbers of empirical relations between the unreddened (B-V)o color index and the superficial effective temperature of a star, are available in literature. They are:

1) Flower

2) Johnson

3) Eggen

4) Bohm - Vitense

5) Cameron - Reed

6) Arribas & Martinez-Roger

Flower, Johnson, Eggen and Bohm-Vitense

Excluding the Cameron - Reed and Arribas & Martinez - Roger relations, all the other relations can be obtained through a polynomial fitting between empirical data. The general shape for the Flower, Johnson, Eggen and Bohm-Vitense empirical calibrations are:

The previous general equation is a 6th order polynomial that can be used with the Johnson, Eggen and Bohm-Vitense calibrations

While the 7th order polynomial equation must be used with the Flower empirical calibration. Where Te = effective temperature and (B-V) is the relative unreddened color.

The coefficients for the various polynomials are:

While the fields of applicability of the polynomial calibrations are:

Whit some limitations we can also use the following two emprical calibrations:

Cameron-Reed

The Cameron-Reed calibration works well in two well defined steps of temperature that is: Te < 9150 K for the previous equation and Te > 9150 K for the next equation.

Arribas and Martinez-Roger

The Arribas and Martinez-Rogers is instead applicable in the temperature range: 5000 < Te < 8000 K.

References

---

© 2006 - Valter Arnò