On the Radial Distribution of Horizontal Branch Stars in Ngc 2808

Content Provider	Semantic Scholar
Author	Iannicola, G. Monelli, Marco Bono, Giuseppe Stetson, Peter B. Buonanno, Roberto Calamida, Annalisa Zoccali, Manuela Caputo, Filippina Castellani, M. Corsi, Claudia Ora, M. Dall’ Cecco, A. Di Innocenti, S. Degl’ Ferraro, I. Nonino, Mario Pietrinferni, Adriano Pulone, Luigi Moroni, Pier Giorgio Prada Romaniello, Maria Sanna, Nico Walker, Alistair R.
Copyright Year	2009
Abstract	We present accurate new ultraviolet and optical BVI photometry for the Galactic globular cluster NGC 2808, based on both ground-based and archival HST imagery. From this we have selected a sample of ∼2,000 HB stars; given the extensive wavelength range considered and the combination of both high-angular-resolution and wide-field photometric coverage, our sample should be minimally biased. We divide the HB stars into three radial bins and find that the relative fractions of cool, hot and extreme HB stars do not change radically when moving from the center to the outskirts of the cluster: the difference is typically smaller than ∼2σ. These results argue against the presence of strong radial differentiation among any stellar subpopulations having distinctly different helium abundances. The ratio between HB and RG stars brighter than the ZAHB steadly increases when moving from the innermost to the outermost cluster regions. The difference is larger than ∼4σ and indicates a deficiency of bright RGs in the outskirts of the cluster. Subject headings: globular clusters: general — globular clusters: individual (NGC2808) — stars: horizontal-branch
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://arxiv.org/pdf/0903.4531v1.pdf
Language	English
Access Restriction	Open
Subject Keyword	ABRA gene Angular defect AngularJS Archive Cool - action Helium Large Medical Subject Headings New General Catalogue Photometry Radial (radio) Radial basis function Residential gateway Stars, Celestial Stellar (payment network) wavelength
Content Type	Text
Resource Type	Article