Major substructure in the M31 outer halo:  the South-West Cloud

N. F. Bate; A. R. Conn; B. McMonigal; G. F. Lewis; N. F. Martin; A. W. McConnachie; J. Veljanoski; A. D. Mackey; A. M. N. Ferguson; R. A. Ibata; M. J. Irwin; M. Fardal; A. P. Huxor; A. Babul

doi:10.1093/mnras/stt2139

Major substructure in the M31 outer halo: the South-West Cloud

N. F. Bate^*, A. R. Conn, B. McMonigal, G. F. Lewis, N. F. Martin, A. W. McConnachie, J. Veljanoski, A. D. Mackey, A. M. N. Ferguson, R. A. Ibata, M. J. Irwin, M. Fardal, A. P. Huxor, A. Babul

^*Corresponding author for this work

Faculty of Computing, Engineering and Science

Research output: Contribution to journal › Article › peer-review

Abstract

We undertake the first detailed analysis of the stellar population and spatial properties of a diffuse substructure in the outer halo of M31. The South-West Cloud lies at a projected distance of similar to 100 kpc from the centre of M31 and extends for at least similar to 50 kpc in projection. We use Pan-Andromeda Archaeological Survey photometry of red giant branch stars to determine a distance to the South-West Cloud of 793(-45)(+45) kpc. The metallicity of the cloud is found to be [Fe/H] = -1.3 +/- 0.1. This is consistent with the coincident globular clusters PAndAS-7 and PAndAS-8, which have metallicities determined using an independent technique of [Fe/H] = -1.35 +/- 0.15. We measure a brightness for the Cloud of M-V = -12.1 mag; this is similar to 75 per cent of the luminosity implied by the luminosity-metallicity relation. Under the assumption that the South-West Cloud is the visible remnant of an accreted dwarf satellite, this suggests that the progenitor object was amongst M31's brightest dwarf galaxies prior to disruption.

Original language	English
Pages (from-to)	3362-3372
Number of pages	11
Journal	Monthly Notices of the Royal Astronomical Society
Volume	437
Issue number	4
DOIs	https://doi.org/10.1093/mnras/stt2139
Publication status	Published - Feb 2014

Keywords

galaxies: individual: M31
Local Group
galaxies: stellar content
GIANT BRANCH TIP
GLOBULAR-CLUSTER SYSTEM
DWARF GALAXY
SAGITTARIUS DWARF
ANDROMEDA GALAXY
3-DIMENSIONAL STRUCTURE
STELLAR OVERDENSITY
BAYESIAN-APPROACH
LOCAL GROUP
STREAM

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Bate, N. F., Conn, A. R., McMonigal, B., Lewis, G. F., Martin, N. F., McConnachie, A. W., Veljanoski, J., Mackey, A. D., Ferguson, A. M. N., Ibata, R. A., Irwin, M. J., Fardal, M., Huxor, A. P., & Babul, A. (2014). Major substructure in the M31 outer halo: the South-West Cloud. Monthly Notices of the Royal Astronomical Society, 437(4), 3362-3372. https://doi.org/10.1093/mnras/stt2139

@article{ddc7e2473b0240c7881a9db1374da5d3,

title = "Major substructure in the M31 outer halo: the South-West Cloud",

abstract = "We undertake the first detailed analysis of the stellar population and spatial properties of a diffuse substructure in the outer halo of M31. The South-West Cloud lies at a projected distance of similar to 100 kpc from the centre of M31 and extends for at least similar to 50 kpc in projection. We use Pan-Andromeda Archaeological Survey photometry of red giant branch stars to determine a distance to the South-West Cloud of 793(-45)(+45) kpc. The metallicity of the cloud is found to be [Fe/H] = -1.3 +/- 0.1. This is consistent with the coincident globular clusters PAndAS-7 and PAndAS-8, which have metallicities determined using an independent technique of [Fe/H] = -1.35 +/- 0.15. We measure a brightness for the Cloud of M-V = -12.1 mag; this is similar to 75 per cent of the luminosity implied by the luminosity-metallicity relation. Under the assumption that the South-West Cloud is the visible remnant of an accreted dwarf satellite, this suggests that the progenitor object was amongst M31's brightest dwarf galaxies prior to disruption.",

keywords = "galaxies: individual: M31, Local Group, galaxies: stellar content, GIANT BRANCH TIP, GLOBULAR-CLUSTER SYSTEM, DWARF GALAXY, SAGITTARIUS DWARF, ANDROMEDA GALAXY, 3-DIMENSIONAL STRUCTURE, STELLAR OVERDENSITY, BAYESIAN-APPROACH, LOCAL GROUP, STREAM",

author = "Bate, {N. F.} and Conn, {A. R.} and B. McMonigal and Lewis, {G. F.} and Martin, {N. F.} and McConnachie, {A. W.} and J. Veljanoski and Mackey, {A. D.} and Ferguson, {A. M. N.} and Ibata, {R. A.} and Irwin, {M. J.} and M. Fardal and Huxor, {A. P.} and A. Babul",

year = "2014",

month = feb,

doi = "10.1093/mnras/stt2139",

language = "English",

volume = "437",

pages = "3362--3372",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

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TY - JOUR

T1 - Major substructure in the M31 outer halo

T2 - the South-West Cloud

AU - Bate, N. F.

AU - Conn, A. R.

AU - McMonigal, B.

AU - Lewis, G. F.

AU - Martin, N. F.

AU - McConnachie, A. W.

AU - Veljanoski, J.

AU - Mackey, A. D.

AU - Ferguson, A. M. N.

AU - Ibata, R. A.

AU - Irwin, M. J.

AU - Fardal, M.

AU - Huxor, A. P.

AU - Babul, A.

PY - 2014/2

Y1 - 2014/2

N2 - We undertake the first detailed analysis of the stellar population and spatial properties of a diffuse substructure in the outer halo of M31. The South-West Cloud lies at a projected distance of similar to 100 kpc from the centre of M31 and extends for at least similar to 50 kpc in projection. We use Pan-Andromeda Archaeological Survey photometry of red giant branch stars to determine a distance to the South-West Cloud of 793(-45)(+45) kpc. The metallicity of the cloud is found to be [Fe/H] = -1.3 +/- 0.1. This is consistent with the coincident globular clusters PAndAS-7 and PAndAS-8, which have metallicities determined using an independent technique of [Fe/H] = -1.35 +/- 0.15. We measure a brightness for the Cloud of M-V = -12.1 mag; this is similar to 75 per cent of the luminosity implied by the luminosity-metallicity relation. Under the assumption that the South-West Cloud is the visible remnant of an accreted dwarf satellite, this suggests that the progenitor object was amongst M31's brightest dwarf galaxies prior to disruption.

AB - We undertake the first detailed analysis of the stellar population and spatial properties of a diffuse substructure in the outer halo of M31. The South-West Cloud lies at a projected distance of similar to 100 kpc from the centre of M31 and extends for at least similar to 50 kpc in projection. We use Pan-Andromeda Archaeological Survey photometry of red giant branch stars to determine a distance to the South-West Cloud of 793(-45)(+45) kpc. The metallicity of the cloud is found to be [Fe/H] = -1.3 +/- 0.1. This is consistent with the coincident globular clusters PAndAS-7 and PAndAS-8, which have metallicities determined using an independent technique of [Fe/H] = -1.35 +/- 0.15. We measure a brightness for the Cloud of M-V = -12.1 mag; this is similar to 75 per cent of the luminosity implied by the luminosity-metallicity relation. Under the assumption that the South-West Cloud is the visible remnant of an accreted dwarf satellite, this suggests that the progenitor object was amongst M31's brightest dwarf galaxies prior to disruption.

KW - galaxies: individual: M31

KW - Local Group

KW - galaxies: stellar content

KW - GIANT BRANCH TIP

KW - GLOBULAR-CLUSTER SYSTEM

KW - DWARF GALAXY

KW - SAGITTARIUS DWARF

KW - ANDROMEDA GALAXY

KW - 3-DIMENSIONAL STRUCTURE

KW - STELLAR OVERDENSITY

KW - BAYESIAN-APPROACH

KW - LOCAL GROUP

KW - STREAM

U2 - 10.1093/mnras/stt2139

DO - 10.1093/mnras/stt2139

M3 - Article

VL - 437

SP - 3362

EP - 3372

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -

Major substructure in the M31 outer halo: the South-West Cloud

Abstract

Keywords

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