NOAO > Observing Info > Approved Programs > 2010B-0230
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NOAO > Observing Info > Approved Programs > 2010B-0230 |
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PI: Alistair Walker, NOAO/CTIO, awalker@ctio.noao.edu
Address: Casilla 603, La Serena, Chile
CoI: Gloria Andreuzzi, INAF-Telescopio Nazionale Galileo
CoI: Giuseppe Bono, Universita Tor Vergata de Roma
CoI: Alessandra Di Cecco, Universita Tor Vergata de Roma
CoI: Andrea Kunder, NOAO/CTIO
CoI: Peter Stetson, Hertzberg Institute of Astrophysics
Title: Multipopulations in NGC 2808: helium or not helium?
Abstract:
Galactic globular clusters, almost without exception, have long been
thought to be excellent examples of simple stellar populations.
However, from HST photometry, many have been shown to exhibit multiple
populations, but the diversity shown and observational difficulties mean
that we are far from a definitive consensus for explaining the early
evolution and enrichment history for globulars. Here we plan to collect
accurate and deep NIR (J,K) images for the galactic globular cluster NGC
2808. The new images together with optical (B,V,I) data already
available to our group will allow us to constrain the nature of the
multiple populations detected in this stellar system. A popular working
hypothesis is that they are caused by the stars in each population
having different helium abundances, attributed to successive
enhancements from multiple bursts of star formation in the early life of
the cluster. However so far all evidence to support this scenario is
indirect. We will test this, with the key advantage of our
observational strategy being that optical-NIR (V-K, B-K) colors are a
factor of two more sensitive to an increase in helium than optical (V-I,
B-I) colors.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2010B-0230 |
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