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New Candidate EHB Stars in the Open Cluster NGC 6791: Looking Locally Into the UV-Upturn Phenomenon

Journal
Date Issued
2006
Author(s)
Buson, L. M.
•
Bertone, E.
•
•
Carraro, G.
Abstract
Relying on U and B imagery at the Italian Telescopio Nazionale Galileo (TNG), we report here the discovery of a sample of 13 new UV-bright post-HB candidate stars in the field of the Galactic open cluster NGC 6791. Owing to its super-solar metal content ([Fe/H] ≳ 0.2 dex) and estimated age (t ≳ 8 Gyr), this cluster represents the nearest and ideal stellar aggregate to match the distinctive properties of the evolved stellar populations possibly ruling the UV-upturn phenomenon in elliptical galaxies and bulges of spirals. Our ongoing spectroscopic follow-up of this unique UV-bright sample will allow us to assess -- once cluster membership of the candidates is properly checked -- the real nature (e.g., sdB, sdO, AGB-manqué or EHB stars) of these hot sources and their link with the ultraviolet excess emerging from low-mass, metal-rich evolutionary environments of external galaxies.
Volume
15
Start page
49
Uri
Issn Identifier
1392-0049
Ads BibCode
2006BaltA..15...49B
Rights
open.access
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