SCYON Abstract

Received on April 29 2008

Spitzer Space Telescope evidence in NGC 6791: no super-mass-loss at super-solar metallicity to explain helium white dwarfs?

Authors	Jacco Th. van Loon (¹), Martha L. Boyer (²), and Iain McDonald (¹)
Affiliation	(¹) Keele University, UK (²) University of Minnesota, USA
To appear in	Astrophysical Journal Letters
Contact	jacco@astro.keele.ac.uk
URL
Links	NGC 6791

Abstract

We use archival Spitzer Space Telescope photometry of the old, super-solar metallicity massive open cluster NGC 6791 to look for evidence of enhanced mass loss, which has been postulated to explain the optical luminosity function and low white dwarf masses in this benchmark cluster. We find a conspicuous lack of evidence for prolificacy of circumstellar dust production that would have been expected to accompany such mass loss. We also construct the optical and infrared luminosity functions, and demonstrate that these fully agree with theoretical expectations. We thus conclude that there is no evidence for the mass loss of super-solar metallicity red giants to be sufficiently high that they can avoid the helium flash at the tip of the red giant branch.