Rediscovery of the Sixth Star Cluster in the Fornax Dwarf Spheroidal Galaxy Academic Article uri icon

abstract

  • 2019. The American Astronomical Society. All rights reserved.. 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 6-6.7 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.

published proceedings

  • ASTROPHYSICAL JOURNAL LETTERS

altmetric score

  • 8.08

author list (cited authors)

  • Wang, M. Y., Koposov, S., Drlica-Wagner, A., Pieres, A., Li, T. S., de Boer, T., ... Walker, A. R.

citation count

  • 20

complete list of authors

  • Wang, MY||Koposov, S||Drlica-Wagner, A||Pieres, A||Li, TS||de Boer, T||Bechtol, K||Belokurov, V||Pace, AB||Bacon, D||Abbott, TMC||Annis, J||Bertin, E||Brooks, D||Buckley-Geer, E||Burke, DL||Rosell, A Carnero||Kind, M Carrasco||Carretero, J||da Costa, LN||De Vicente, J||Desai, S||Diehl, HT||Doel, P||Estrada, J||Flaugher, B||Fosalba, P||Frieman, J||García-Bellido, J||Gerdes, DW||Gruen, D||Gruendl, RA||Gschwend, J||Gutierrez, G||Hollowood, DL||Honscheid, K||Hoyle, B||James, DJ||Kent, S||Kuehn, K||Kuropatkin, N||Maia, MAG||Marshall, JL||Menanteau, F||Miquel, R||Plazas, AA||Sanchez, E||Santiago, B||Scarpine, V||Schindler, R||Schubnell, M||Serrano, S||Sevilla-Noarbe, I||Smith, M||Smith, RC||Sobreira, F||Suchyta, E||Swanson, MEC||Tarle, G||Thomas, D||Tucker, DL||Walker, AR

publication date

  • April 2019