The M33 varjable star population revealed by Spitzer

Kristen B McQuinn; Chick E Woodward; S. P. Willner; E. F. Polomski; Robert D Gehrz; Roberta M Humphreys; Jacco Th Van Loon; M. L.N. Ashby; K. Eicher; G. G. Fazio

doi:10.1086/519068

The M33 varjable star population revealed by Spitzer

Kristen B McQuinn, Chick E Woodward, S. P. Willner, E. F. Polomski, Robert D Gehrz, Roberta M Humphreys, Jacco Th Van Loon, M. L.N. Ashby, K. Eicher, G. G. Fazio

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Abstract

We analyze five epochs of Spitzer Space Telescope Infrared Array Camera (IRAC) observations of the nearby spiral galaxy M33. Each epoch covered nearly a square degree at 3.6,4.5, and 8.0 μm. The point-source catalog from the full data set contains 37,650 stars. The stars have luminosities characteristic of the asymptotic giant branch and can be separated into oxygen-rich and carbon-rich populations by their [3.6] - [4.5] colors. The [3.6] - [8.0] colors indicate that over 80% of the stars detected at 8.0 μm have dust shells. Photometric comparison of epochs using conservative criteria yields a catalog of 2923 variable stars. These variables are most likely long-period variables amid an evolved stellar population. At least one-third of the identified carbon stars are variable.

Original language	English (US)
Pages (from-to)	850-861
Number of pages	12
Journal	Astrophysical Journal
Volume	664
Issue number	2 I
DOIs	https://doi.org/10.1086/519068
State	Published - Aug 1 2007

Keywords

Galaxies: individual (M33)
Galaxies: stellar content
Infrared: stars
Stars: AGB and post-AGB
Stars: Variables: other

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title = "The M33 varjable star population revealed by Spitzer",

abstract = "We analyze five epochs of Spitzer Space Telescope Infrared Array Camera (IRAC) observations of the nearby spiral galaxy M33. Each epoch covered nearly a square degree at 3.6,4.5, and 8.0 μm. The point-source catalog from the full data set contains 37,650 stars. The stars have luminosities characteristic of the asymptotic giant branch and can be separated into oxygen-rich and carbon-rich populations by their [3.6] - [4.5] colors. The [3.6] - [8.0] colors indicate that over 80% of the stars detected at 8.0 μm have dust shells. Photometric comparison of epochs using conservative criteria yields a catalog of 2923 variable stars. These variables are most likely long-period variables amid an evolved stellar population. At least one-third of the identified carbon stars are variable.",

keywords = "Galaxies: individual (M33), Galaxies: stellar content, Infrared: stars, Stars: AGB and post-AGB, Stars: Variables: other",

author = "McQuinn, {Kristen B} and Woodward, {Chick E} and Willner, {S. P.} and Polomski, {E. F.} and Gehrz, {Robert D} and Humphreys, {Roberta M} and {Van Loon}, {Jacco Th} and Ashby, {M. L.N.} and K. Eicher and Fazio, {G. G.}",

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AU - McQuinn, Kristen B

AU - Woodward, Chick E

AU - Willner, S. P.

AU - Polomski, E. F.

AU - Gehrz, Robert D

AU - Humphreys, Roberta M

AU - Van Loon, Jacco Th

AU - Ashby, M. L.N.

AU - Eicher, K.

AU - Fazio, G. G.

PY - 2007/8/1

Y1 - 2007/8/1

N2 - We analyze five epochs of Spitzer Space Telescope Infrared Array Camera (IRAC) observations of the nearby spiral galaxy M33. Each epoch covered nearly a square degree at 3.6,4.5, and 8.0 μm. The point-source catalog from the full data set contains 37,650 stars. The stars have luminosities characteristic of the asymptotic giant branch and can be separated into oxygen-rich and carbon-rich populations by their [3.6] - [4.5] colors. The [3.6] - [8.0] colors indicate that over 80% of the stars detected at 8.0 μm have dust shells. Photometric comparison of epochs using conservative criteria yields a catalog of 2923 variable stars. These variables are most likely long-period variables amid an evolved stellar population. At least one-third of the identified carbon stars are variable.

AB - We analyze five epochs of Spitzer Space Telescope Infrared Array Camera (IRAC) observations of the nearby spiral galaxy M33. Each epoch covered nearly a square degree at 3.6,4.5, and 8.0 μm. The point-source catalog from the full data set contains 37,650 stars. The stars have luminosities characteristic of the asymptotic giant branch and can be separated into oxygen-rich and carbon-rich populations by their [3.6] - [4.5] colors. The [3.6] - [8.0] colors indicate that over 80% of the stars detected at 8.0 μm have dust shells. Photometric comparison of epochs using conservative criteria yields a catalog of 2923 variable stars. These variables are most likely long-period variables amid an evolved stellar population. At least one-third of the identified carbon stars are variable.

KW - Galaxies: individual (M33)

KW - Galaxies: stellar content

KW - Infrared: stars

KW - Stars: AGB and post-AGB

KW - Stars: Variables: other

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JO - Astrophysical Journal

JF - Astrophysical Journal

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ER -

The M33 varjable star population revealed by Spitzer

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Keywords

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