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arXiv · 1507.06654

The shell game: a panoramic view of Fornax

N. F. Bate·B. McMonigal·G. F. Lewis·M. J. Irwin·E. Gonzalez-Solares·T. Shanks·N. Metcalfe
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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 square degrees 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 coeval with the horizontal branch population. Second, a shell structure located approximately 1.4 degrees 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.

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N. F. Bate, B. McMonigal, G. F. Lewis, M. J. Irwin, E. Gonzalez-Solares, T. Shanks, N. Metcalfe. 2015-07-23. The shell game: a panoramic view of Fornax. https://doi.org/10.1093/mnras%2Fstv1684

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