A consistency test of white dwarf and main sequence ages: NGC 6791

E García-Berro,S Torres,A.H Córsico,M Salaris,J Isern,L.G Althaus,J Montalbán,V Van Grootel,A Noels

doi:10.1051/epjconf/20134305003

Abstract

NGC 6791 is an open cluster that it is so close to us that can be imaged down to very faint luminosities. The main sequence turn-off age (∼8 Gyr) and the age derived from the cut-off of the white dwarf luminosity function (∼6 Gyr) were found to be significantly different. Here we demonstrate that the origin of this age discrepancy lies in an incorrect evaluation of the white dwarf cooling ages, and we show that when the relevant physical separation processes are included in the calculation of white dwarf sequences both ages are coincident.

Highlights

NGC 6791 is a very well studied, metal-rich ([Fe/H]∼ +0.4), well populated (∼ 3, 000 stars) and very old (∼ 8 Gyr) open cluster that can be imaged down to very faint luminosities [1]
The main sequence turn-off age (∼ 8 Gyr) and the age derived from the cut-off of the white dwarf luminosity function (∼ 6 Gyr) were found to be significantly different
We demonstrate that the origin of this age discrepancy lies in an incorrect evaluation of the white dwarf cooling ages, and we show that when the relevant physical separation processes are included in the calculation of white dwarf sequences both ages are coincident

Summary

Introduction

NGC 6791 is a very well studied, metal-rich ([Fe/H]∼ +0.4), well populated (∼ 3, 000 stars) and very old (∼ 8 Gyr) open cluster that can be imaged down to very faint luminosities [1]. NGC 6791 is an open cluster that it is so close to us that can be imaged down to very faint luminosities.

Results

Conclusion