The shell game: a panoramic view of Fornax

Bate, N.F.; McMonigal, B.; Lewis, G.F.; Irwin, M.J.; Gonzalez-Solares, E.; Shanks, T.; Metcalfe, N.

Abstract

We present a panoramic study of the Fornax dwarf spheroidal galaxy, using data obtained as part of the VLT Survey Telescope (VST) ATLAS Survey. The data presented here – a subset of the full survey – uniformly cover a region of 25 deg2 centred on the galaxy, in g, r and i bands. This large area coverage reveals two key differences to previous studies of Fornax. First, data extending beyond the nominal tidal radius of the dwarf highlight the presence of a second distinct red giant branch population. This bluer red giant branch appears to be co-eval with the horizontal branch population. Secondly, a shell structure located approximately 1 ∘ . .∘ 4 from the centre of Fornax is shown to be a mis-identified background overdensity of galaxies. This last result casts further doubt on the hypothesis that Fornax underwent a gas-rich merger in its relatively recent past.

Citation

Bate, N., McMonigal, B., Lewis, G., Irwin, M., Gonzalez-Solares, E., Shanks, T., & Metcalfe, N. (2015). The shell game: a panoramic view of Fornax. Monthly Notices of the Royal Astronomical Society, 453(1), 690-703. https://doi.org/10.1093/mnras/stv1684

• Journal Article Type: Article
• Acceptance Date: Jul 22, 2015
• Online Publication Date: Aug 17, 2015
• Publication Date: Oct 11, 2015
• Deposit Date: Feb 10, 2016
• Publicly Available Date: Feb 18, 2016
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 453
• Issue: 1
• Pages: 690-703
• DOI: https://doi.org/10.1093/mnras/stv1684
• Keywords: Galaxies: dwarf, Galaxies: individual: Fornax dSph, Local Group, Galaxies: stellar content.