Empirical calibration of the 4000 A break

J. Gorgas, N. Cardiel, S. Pedraz, and J.J. Gonzalez
Astron. Astrophys. Suppl. Ser., 139, 29-41 (1999)

Abstract

Empirical fitting functions, describing the behaviour of the 4000 A break, D4000, in terms of effective temperature, metallicity and surface gravity, are presented. For this purpose, the break has been measured in 392 stars from the Lick/IDS Library. We have followed a very detailed error treatment in the reduction and fitting procedures, allowing for a reliable estimation of the break uncertainties. This calibration can be easily incorporated into stellar population models to provide accurate predictions of the break amplitude for, relatively old, composite systems.

	Full preprint including table with star data.
	FORTRAN subroutine to compute the D4000 as a function of the input stellar parameters Teff, [Fe/H] and log(g).
	Table 1 is also available in electronic form at the CDS via: anonymous ftp to cdsarc.u-strasbg.fr/pub/cats/J/A+AS/139/29 , or via http://cdsweb.u-strasbg.fr/cgi-bin/CaT?J/A+AS/139/29.