Ma, J., de Grijs, R., Chen, D. et al. (8 more authors) (2007) Structural parameters of mayall II=G1 in M31. Monthly Notices of the Royal Astronomical Society, 376 (4). pp. 1621-1629. ISSN 0035-8711
Abstract
Mayall II = G1 is one of the most luminous globular clusters (GCs) known in M31. New deep, high-resolution observations with the Advanced Camera for Surveys on the Hubble Space Telescope are used to provide accurate photometric data to the smallest radii yet. In particular, we present the precise variation of ellipticity and position angle, and of surface brightness for the core of the object. Based on these accurate photometric data, we redetermine the structural parameters of G1 by fitting a single-mass isotropic King model. We derive a core radius, rc= 0.21 ± 0.01 arcsec (= 0.78 ± 0.04 pc), a tidal radius, rt= 21.8 ± 1.1 arcsec (= 80.7 ± 3.9 pc), and a concentration index c= log (rt/rc) = 2.01 ± 0.02. The central surface brightness is 13.510 mag arcsec−2. We also calculate the half-light radius, at rh= 1.73 ± 0.07 arcsec (= 6.5 ± 0.3 pc). The results show that, within 10 core radii, a King model fits the surface brightness distribution well. We find that this object falls in the same region of the MV versus log Rh diagram as ω Centauri, M54 and NGC 2419 in the Milky Way. All three of these objects have been claimed to be the stripped cores of now defunct dwarf galaxies. We discuss in detail whether GCs, stripped cores of dwarf spheroidals and normal dwarf galaxies form a continuous distribution in the MV versus log Rh plane, or if GCs and dwarf spheroidals constitute distinct classes of objects; we present arguments in favour of this latter view.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2007 The Author(s). Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | globular clusters: individual: Mayall II = G1; galaxies: evolution; galaxies: individual: M31 |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 29 Mar 2019 16:23 |
Last Modified: | 01 Apr 2019 11:59 |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1111/j.1365-2966.2007.11573.x |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:138903 |