SCYON Abstract

Received on September 19 2006

ACS photometry of the globular cluster B514

Authors	S. Galleti, L. Federici, M. Bellazzini, A. Buzzoni, and F. Fusi Pecci
Affiliation	INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127, Bologna, Italy
Accepted by	Astrophysical Journal
Contact	silvia.galleti2@unibo.it
URL	http://www.arxiv.org/abs/astro-ph/0609439
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Abstract

We present deep F606W, F814W ACS photometry of the recently discovered globular cluster B514, the outermost known globular in the M31 galaxy. The cluster appears quite extended and member stars are unequivocally identified out to ∼200 pc from the center. The Color Magnitude Diagram reveals a steep Red Giant Branch (RGB), and a Horizontal Branch (HB) extending blue ward of the instability strip, indicating that B514 is a classical old metal-poor globular cluster. The RGB locus and the position of the RGB Bump are both consistent with a metallicity [Fe/H]∼-1.8, in excellent agreement with spectroscopic estimates. A preliminary estimate of the integrated absolute V magnitude (M_V<-9.1) suggests that B514 is among the brightest globulars of M31.