천문학회보 (The Bulletin of The Korean Astronomical Society)
- 제46권1호
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- Pages.52.2-52.2
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- 2021
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- 1226-2692(pISSN)
The Origin of the Type III Component in the Black Eye Galaxy M64
- Kang, Jisu (Seoul National University) ;
- Kim, Yoo Jung (Seoul National University) ;
- Lee, Myung Gyoon (Seoul National University) ;
- Jang, In Sung (University of Chicago)
- 발행 : 2021.04.13
초록
The Black Eye Galaxy M64 is an intriguing spiral galaxy with a Type III disk break. To trace the origin of its Type III component, we present HST/ACS F606W/F814W photometry of resolved stars in the outer disk of M64 (2.5' < R < 6.5'). First, we discover a bright extended globular cluster (GC) M64-GC1 at R ~ 5.5', and find that it is an old metal-poor halo GC ([Fe/H] = -1.5 +/- 0.2). Second, we find that there are two distinct subpopulations of red giant branch stars (RGBs). One is an old metal-rich ([Fe/H] ~ -0.4) disk population, and the other is an old metal-poor halo population similar to the resolved stars in M64-GC1. The radial number density profile of the metal-rich RGB follows an exponential disk law, while that of the metal-poor RGB follows a de Vaucouleurs's low. From these results, we conclude that the origin of the Type III component in M64 is a halo, not a disk or a bulge. We will further discuss the results in regards to the formation and evolution of M64.
키워드