Rediscovery of the Sixth Star Cluster in the Fornax Dwarf Spheroidal Galaxy

Wang, M. Y. and Koposov, S. and Drlica-Wagner, A. and Pieres, A. and Li, T. S. and de Boer, T. and Bechtol, K. and Belokurov, V. and Pace, A. B. and Bacon, D. and Abbott, T. M. C. and Annis, J. and Bertin, E. and Brooks, D. and Buckley-Geer, E. and Burke, D. L. and Rosell, A. Carnero and Kind, M. Carrasco and Carretero, J. and da Costa, L. N. and De Vicente, J. and Desai, S. and Diehl, H. T. and Doel, P. and Estrada, J. and Flaugher, B. and Fosalba, P. and Frieman, J. and García-Bellido, J. and Gerdes, D. W. and Gruen, D. and Gruendl, R. A. and Gschwend, J. and Gutierrez, G. and Hollowood, D. L. and Honscheid, K. and Hoyle, B. and James, D. J. and Kent, S. and Kuehn, K. and Kuropatkin, N. and Maia, M. A. G. and Marshall, J. L. and Menanteau, F. and Miquel, R. and Plazas, A. A. and Sanchez, E. and Santiago, B. and Scarpine, V. and Schindler, R. and Schubnell, M. and Serrano, S. and Sevilla-Noarbe, I. and Smith, M. and Smith, R. C. and Sobreira, F. and Suchyta, E. and Swanson, M. E. C. and Tarle, G. and Thomas, D. and Tucker, D. L. and Walker, A. R. (2019) Rediscovery of the Sixth Star Cluster in the Fornax Dwarf Spheroidal Galaxy. The Astrophysical Journal, 875 (2). L13. ISSN 2041-8213

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Abstract

Since first noticed by Shapley in 1939, a faint object coincident with the Fornax dwarf spheroidal has long been discussed as a possible sixth globular cluster (GC) system. However, debate has continued over whether this overdensity is a statistical artifact or a blended galaxy group. In this Letter we demonstrate, using deep DECam imaging data, that this object is well resolved into stars and is a bona fide star cluster. The stellar overdensity of this cluster is statistically significant at the level of ∼6–6.7σ in several different photometric catalogs including Gaia. Therefore, it is highly unlikely to be caused by random fluctuation. We show that Fornax 6 is a star cluster with a peculiarly low surface brightness and irregular shape, which may indicate a strong tidal influence from its host galaxy. The Hess diagram of Fornax 6 is largely consistent with that of Fornax field stars, but it appears to be slightly bluer. However, it is still likely more metal-rich than most of the GCs in the system. Faint clusters like Fornax 6 that orbit and potentially get disrupted in the centers of dwarf galaxies can prove crucial for constraining the dark matter distribution in Milky Way satellites.

Item Type: Article
Subjects: Afro Asian Archive > Physics and Astronomy
Depositing User: Unnamed user with email support@afroasianarchive.com
Date Deposited: 05 Jun 2023 05:42
Last Modified: 05 Sep 2024 11:35
URI: http://info.stmdigitallibrary.com/id/eprint/918

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