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arXiv · 0907.1082

A Photometric Metallicity Estimate of the Virgo Stellar Overdensity

Deokkeun An·Jennifer A. Johnson·Timothy C. Beers·Marc H. Pinsonneault·Donald M. Terndrup·Franck Delahaye·Young Sun Lee·Thomas Masseron·Brian Yanny
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Abstract

We determine photometric metal abundance estimates for individual main-sequence stars in the Virgo Overdensity (VOD), which covers almost 1000 deg^2 on the sky, based on a calibration of the metallicity sensitivity of stellar isochrones in the gri filter passbands using field stars with well-determined spectroscopic metal abundances. Despite the low precision of the method for individual stars, we derive [Fe/H] = -2.0 +/-0.1 (internal) +/-0.5 (systematic) for the metal abundance of the VOD from photometric measurements of 0.7 million stars in the Northern Galactic hemisphere with heliocentric distances from ~10 kpc to ~20 kpc. The metallicity of the VOD is indistinguishable, within Delta [Fe/H] < 0.2, from that of field halo stars covering the same distance range. This initial application suggests that the SDSS gri passbands can be used to probe the properties of main-sequence stars beyond ~10 kpc, complementing studies of nearby stars from more metallicity-sensitive color indices that involve the u passband.

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Deokkeun An, Jennifer A. Johnson, Timothy C. Beers, Marc H. Pinsonneault, Donald M. Terndrup, Franck Delahaye, Young Sun Lee, Thomas Masseron, Brian Yanny. 2009-07-06. A Photometric Metallicity Estimate of the Virgo Stellar Overdensity. https://doi.org/10.1088/0004-637x/707/1/l64

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