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47 Tucanae: The Spectroscopic versus CMD Age Discrepancy

Published online by Cambridge University Press:  03 August 2017

Alexandre Vazdekis ,
Maurizio Salaris ,
Nobuo Arimoto  and
James A. Rose
Alexandre Vazdekis
Affiliation:
Instituto de Astrofísica de Canarias, La Laguna 38200, Tenerife, Spain. E-mail: [email protected]
Maurizio Salaris
Affiliation:
Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, U.K.
Nobuo Arimoto
Affiliation:
Institute of Astronomy, University of Tokyo, Osawa 2-21-1, Mitaka, Tokyo 181-0015, Japan
James A. Rose
Affiliation:
Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599, U.S.A.

Abstract

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We investigate the origin of the discrepancy between the age estimates based on the Color-Magnitude-Diagram and the integrated spectra of 47 Tuc. Using a newly defined Hγ age indicator, with unprecedented power to disentangle the degeneracy between age and metallicity, we confirm the very large spectroscopic age derived for this cluster. We explore a number of key parameters with potential to decrease the Balmer lines and show the necessity of turnoff stars with lower temperatures. We find that alpha-enhanced isochrones with atomic diffusion leads to a younger spectroscopic age in better agreement with the CMD age.

Type
Part 4. Star Cluster Formation and Evolution: Theory and Observation
Information
Symposium - International Astronomical Union , Volume 207: Extragalactic Star Clusters , 2002 , pp. 610 - 615
Copyright
Copyright © Astronomical Society of the Pacific 2002 

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