PROBING THE INTERMEDIATE-AGE GLOBULAR CLUSTERS IN NGC 5128 FROM ULTRAVIOLET OBSERVATIONS

Journal Article · Mon Jul 20 00:00:00 EDT 2009 · Astrophysical Journal (Online)

DOI:https://doi.org/10.1088/0004-637X/700/1/L11; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21313920

Rey, Soo-Chang; Kang, Yongbeom; Lee, Kyeongsook ^[1]; Sohn, Sangmo T; Lee, Young-Wook; Yoon, Suk-Jin; Yi, Sukyoung K; Chung, Chul; Lee, Sang-Yoon ^[2]; Beasley, Michael A ^[3]; Rich, R Michael ^[4]; Bianch, Luciana ^[5]; Barlow, Tom A; Foster, Karl; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick ^[6]; Neff, Susan G ^[7]; Schiminovich, David ^[8]; Seibert, Mark ^[9]

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1. Department of Astronomy and Space Science, Chungnam National University, Daejeon 305-764 (Korea, Republic of)
2. Center for Space Astrophysics, Yonsei University, Seoul 120-749 (Korea, Republic of)
3. Instituto de Astrofisica de Canarias, Via Lactea, E-38200 La Laguna, Tenerife (Spain)
4. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
5. Department of Physics and Astronomy, The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States)
6. California Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
7. Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
8. Department of Astronomy, Columbia University, New York, NY 10027 (United States)
9. Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

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 {approx}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.

• OSTI ID: 21313920
• Journal Information: Astrophysical Journal (Online), Vol. 700, Issue 1; Other Information: DOI: 10.1088/0004-637X/700/1/L11; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-4357
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
COLOR
MILKY WAY
PHOTOMETRY
RED SHIFT
STAR CLUSTERS
STARS
ULTRAVIOLET RADIATION