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Probing the intermediate-age globular clusters in NGS 5128 from ultraviolet observations

Rey, Soo-Chang and Sohn, Sangmo T. and Beasley, Michael A. and Lee, Young-Wook and Rich, R. Michael and Yoon, Suk-Jin and Yi, Sukyoung K. and Bianchi, Luciana and Kang, Yongbeom and Lee, Kyeongsook and Chung, Chul and Lee, Sang-Yoon and Barlow, Tom A. and Foster, Karl and Friedman, Peter G. and Martin, D. Christopher and Morrissey, Patrick and Neff, Susan G. and Schiminovich, David and Seibert, Mark and Wyder, Ted K. and Donas, Jose and Heckman, Timothy M. and Madore, Barry F. and Milliard, Bruno and Szalay, Alex S. and Welsh, Barry Y. (2009) Probing the intermediate-age globular clusters in NGS 5128 from ultraviolet observations. Astrophysical Journal, 700 (1). L11-L15. ISSN 0004-637X.

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We explore the age distribution of the globular cluster (GC) system of the nearby elliptical galaxy NGC 5128 using ultraviolet (UV) photometry from GALEX observations, with UV–optical colors used as the age indicator. Most GCs in NGC 5128 follow the general trends of GCs in M31 and the Milky Way in the UV–optical color– color diagram, which indicates that the majority of GCs in NGC 5128 are old similar to the age range of old GCs in M31 and the Milky Way. A large fraction of spectroscopically identified intermediate-age GC (IAGC) candidates with ~3–8 Gyr are not detected in the far-UV (FUV) passband. Considering the nature of intermediate age populations being faint in the FUV passband, we suggest that many of the spectroscopically identified IAGCs may be truly intermediate in age. This is in contrast to the case of M31 where a large fraction of spectroscopically suggested IAGCs are detected in FUV and therefore may not be genuine IAGCs but rather older GCs with developed blue horizontal branch stars. Our UV photometry strengthens the results previously suggesting the presence of GC and stellar subpopulation with intermediate age in NGC 5128. The existence of IAGCs strongly indicates the occurrence of at least one more major star formation episode after a starburst at high redshift.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rich, R. Michael0000-0003-0427-8387
Bianchi, Luciana0000-0001-7746-5461
Foster, Karl0000-0001-5800-5531
Martin, D. Christopher0000-0002-8650-1644
Morrissey, Patrick0000-0001-8177-1023
Seibert, Mark0000-0002-1143-5515
Madore, Barry F.0000-0002-1576-1676
Additional Information:© 2009 The American Astronomical Society. Received 2009 May 12, accepted for publication 2009 June 12 Published 2009 June 29. We thank Sugata Kaviraj for useful suggestions on the manuscript. This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD; KRF-2005-202-C00158) and the Korea Science and Engineering Foundation (KOSEF) through the Astrophysical Research Center for the Structure and Evolution of the Cosmos (ARCSEC). GALEX (Galaxy Evolution Explorer) is a NASA Small Explorer, launched in 2003 April. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d’Etudes Spatiales of France and the Korean Ministry of Science and Technology.
Group:Space Astrophysics Laboratory
Funding AgencyGrant Number
Korea Research FoundationKRF-2005-202-C00158
Korea Science and Engineering FoundationUNSPECIFIED
Astrophysical Research Center for the Structure and Evolution of the Cosmos (ARCSEC)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Ministry of Science and Technology (Korea)UNSPECIFIED
Subject Keywords:galaxies: individual (NGC 5128); galaxies: star clusters; globular clusters: general; ultraviolet: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20090916-115854862
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15881
Deposited By: Joy Painter
Deposited On:16 Sep 2009 19:49
Last Modified:09 Mar 2020 20:58

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