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Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2016

Major substructure in the M31 outer halo: distances and metallicities along the giant stellar stream

A. Conn
  • Fonction : Auteur
B. Mcmonigal
  • Fonction : Auteur
N. Bate
  • Fonction : Auteur
G. Lewis
  • Fonction : Auteur
R. Ibata
N. Martin
A. Mcconnachie
  • Fonction : Auteur
A. Ferguson
  • Fonction : Auteur
M. Irwin
  • Fonction : Auteur
P. Elahi
  • Fonction : Auteur
K. Venn
  • Fonction : Auteur
A. Mackey
  • Fonction : Auteur

Résumé

We present a renewed look at M31's giant stellar stream along with the nearby structures streams C and D, exploiting a new algorithm capable of fitting to the red giant branch (RGB) of a structure in both colour and magnitude space. Using this algorithm, we are able to generate probability distributions in distance, metallicity and RGB width for a series of subfields spanning these structures. Specifically, we confirm a distance gradient of approximately 20 kpc per degree along a 6 deg extension of the giant stellar stream, with the farthest subfields from M31 lying ∼120 kpc more distant than the innermost subfields. Further, we find a metallicity that steadily increases from −0.7 +0.1 −0.1 to −0.2 +0.2 −0.1 dex along the inner half of the stream before steadily dropping to a value of −1.0 +0.2 −0.2 dex at the farthest reaches of our coverage. The RGB width is found to increase rapidly from 0.4 +0.1 −0.1 to 1.1 +0.2 −0.1 dex in the inner portion of the stream before plateauing and decreasing marginally in the outer subfields of the stream. In addition, we estimate stream C to lie at a distance between 794 and 862 kpc and stream D between 758 and 868 kpc. We estimate the median metallicity of stream C to lie in the range −0.7 to −1.6 dex and a metallicity of −1.1 +0.3 −0.2 dex for stream D. RGB widths for the two structures are estimated to lie in the range 0.4-1.2 dex and 0.3-0.7 dex, respectively. In total, measurements are obtained for 19 subfields along the giant stellar stream, four along stream C, five along stream D and three general M31 spheroid fields for comparison. We thus provide a higher resolution coverage of the structures in these parameters than has previously been available in the literature.
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Dates et versions

hal-03156518 , version 1 (02-03-2021)

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A. Conn, B. Mcmonigal, N. Bate, G. Lewis, R. Ibata, et al.. Major substructure in the M31 outer halo: distances and metallicities along the giant stellar stream. Monthly Notices of the Royal Astronomical Society, 2016, 458 (3), pp.3282-3298. ⟨10.1093/mnras/stw513⟩. ⟨hal-03156518⟩
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