Short-period variable stars in the M31 halo

Andrew E. Dolphin; A. Saha; Edward W. Olszewski; Frank Thim; Evan D. Skillman; J. S. Gallagher; John Hoessel

doi:10.1086/381301

Short-period variable stars in the M31 halo

Andrew E. Dolphin, A. Saha, Edward W. Olszewski, Frank Thim, Evan D. Skillman, J. S. Gallagher, John Hoessel

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

17 Scopus citations

Abstract

We report the findings of a new search for RR Lyrae stars in an M31 halo field located 40′ from the nucleus of the galaxy along the minor axis. We detected 37 variable stars, of which 24 are classified as RR Lyrae and the others are ambiguous. Estimating a completeness fraction of ∼24%, we calculate that there are approximately 100 RR Lyrae stars in the field, which is consistent with what is expected from deep Hubble Space Telescope (HST) color-magnitude diagrams. We calculate a mean magnitude of 〈(g)〉 = 25.15 ± 0.03, which we interpret to mean that the mean metallicity of RR Lyrae stars is significantly lower than that of the M31 halo as a whole. The presence of ancient, metal-poor stars opens the possibility that initially the M31 halo appeared much like the Milky Way halo.

Original language	English (US)
Pages (from-to)	875-896
Number of pages	22
Journal	Astronomical Journal
Volume	127
Issue number	2 1778
DOIs	https://doi.org/10.1086/381301
State	Published - Feb 2004
Externally published	Yes

Keywords

Galaxies: individual (M31)
Local Group
Stars: variables: other

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/381301

Cite this

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title = "Short-period variable stars in the M31 halo",

abstract = "We report the findings of a new search for RR Lyrae stars in an M31 halo field located 40′ from the nucleus of the galaxy along the minor axis. We detected 37 variable stars, of which 24 are classified as RR Lyrae and the others are ambiguous. Estimating a completeness fraction of ∼24%, we calculate that there are approximately 100 RR Lyrae stars in the field, which is consistent with what is expected from deep Hubble Space Telescope (HST) color-magnitude diagrams. We calculate a mean magnitude of 〈(g)〉 = 25.15 ± 0.03, which we interpret to mean that the mean metallicity of RR Lyrae stars is significantly lower than that of the M31 halo as a whole. The presence of ancient, metal-poor stars opens the possibility that initially the M31 halo appeared much like the Milky Way halo.",

keywords = "Galaxies: individual (M31), Local Group, Stars: variables: other",

author = "Dolphin, {Andrew E.} and A. Saha and Olszewski, {Edward W.} and Frank Thim and Skillman, {Evan D.} and Gallagher, {J. S.} and John Hoessel",

year = "2004",

month = feb,

doi = "10.1086/381301",

language = "English (US)",

volume = "127",

pages = "875--896",

journal = "Astronomical Journal",

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TY - JOUR

T1 - Short-period variable stars in the M31 halo

AU - Dolphin, Andrew E.

AU - Saha, A.

AU - Olszewski, Edward W.

AU - Thim, Frank

AU - Skillman, Evan D.

AU - Gallagher, J. S.

AU - Hoessel, John

PY - 2004/2

Y1 - 2004/2

N2 - We report the findings of a new search for RR Lyrae stars in an M31 halo field located 40′ from the nucleus of the galaxy along the minor axis. We detected 37 variable stars, of which 24 are classified as RR Lyrae and the others are ambiguous. Estimating a completeness fraction of ∼24%, we calculate that there are approximately 100 RR Lyrae stars in the field, which is consistent with what is expected from deep Hubble Space Telescope (HST) color-magnitude diagrams. We calculate a mean magnitude of 〈(g)〉 = 25.15 ± 0.03, which we interpret to mean that the mean metallicity of RR Lyrae stars is significantly lower than that of the M31 halo as a whole. The presence of ancient, metal-poor stars opens the possibility that initially the M31 halo appeared much like the Milky Way halo.

AB - We report the findings of a new search for RR Lyrae stars in an M31 halo field located 40′ from the nucleus of the galaxy along the minor axis. We detected 37 variable stars, of which 24 are classified as RR Lyrae and the others are ambiguous. Estimating a completeness fraction of ∼24%, we calculate that there are approximately 100 RR Lyrae stars in the field, which is consistent with what is expected from deep Hubble Space Telescope (HST) color-magnitude diagrams. We calculate a mean magnitude of 〈(g)〉 = 25.15 ± 0.03, which we interpret to mean that the mean metallicity of RR Lyrae stars is significantly lower than that of the M31 halo as a whole. The presence of ancient, metal-poor stars opens the possibility that initially the M31 halo appeared much like the Milky Way halo.

KW - Galaxies: individual (M31)

KW - Local Group

KW - Stars: variables: other

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DO - 10.1086/381301

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JO - Astronomical Journal

JF - Astronomical Journal

SN - 0004-6256

IS - 2 1778

ER -

Short-period variable stars in the M31 halo

Abstract

Keywords

ASJC Scopus subject areas

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