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arXiv · astro-ph/0503397

The white dwarf cooling sequence in NGC 6791

L. R. Bedin·M. Salaris·G. Piotto·I. R. King·J. Anderson·S. Cassisi·Y. Momany·.
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Abstract

In the old, populous, and metal-rich open cluster NGC 6791 we have used deep HST/ACS images to track the white dwarf cooling sequence down to m_F606W~28.5. The white dwarf luminosity function shows a well defined peak at m_F606W~27.4, and a bending to the blue in the color--magnitude diagram. If this peak corresponds to the end of the white dwarf cooling sequence the comparison with theoretical isochrones provides a cluster age estimate of ~2.4 Gyr, in sharp contrast with the age of 8--9 Gyr inferred from the main-sequence turn-off. If the end is at fainter magnitudes, the peak at m_F606W~27.4 is even more enigmatic. We discuss possible causes, none of them very convincing.

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L. R. Bedin, M. Salaris, G. Piotto, I. R. King, J. Anderson, S. Cassisi, Y. Momany, .. 2005-03-17. The white dwarf cooling sequence in NGC 6791. https://doi.org/10.1086/430310

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