The M33 varjable star population revealed by Spitzer

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

Research output: Contribution to journalArticle

50 Citations (Scopus)

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 languageEnglish (US)
Pages (from-to)850-861
Number of pages12
JournalAstrophysical Journal
Volume664
Issue number2 I
DOIs
StatePublished - Aug 1 2007

Fingerprint

time measurement
stars
catalogs
carbon
point source
Mira variables
color
carbon stars
Space Infrared Telescope Facility
variable stars
shell
spiral galaxies
dust
oxygen
point sources
cameras
luminosity
comparison

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

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

Cite this

McQuinn, K. B. W., Woodward, C. E., Willner, S. P., Polomski, E. F., Gehrz, R. D., Humphreys, R. M., ... Fazio, G. G. (2007). The M33 varjable star population revealed by Spitzer. Astrophysical Journal, 664(2 I), 850-861. https://doi.org/10.1086/519068
McQuinn, K. B.W. ; Woodward, Charles E. ; Willner, S. P. ; Polomski, E. F. ; Gehrz, R. D. ; Humphreys, Roberta M. ; Van Loon, Jacco Th ; Ashby, M. L.N. ; Eicher, K. ; Fazio, G. G. / The M33 varjable star population revealed by Spitzer. In: Astrophysical Journal. 2007 ; Vol. 664, No. 2 I. pp. 850-861.
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McQuinn, KBW, Woodward, CE, Willner, SP, Polomski, EF, Gehrz, RD, Humphreys, RM, Van Loon, JT, Ashby, MLN, Eicher, K & Fazio, GG 2007, 'The M33 varjable star population revealed by Spitzer', Astrophysical Journal, vol. 664, no. 2 I, pp. 850-861. https://doi.org/10.1086/519068

The M33 varjable star population revealed by Spitzer. / McQuinn, K. B.W.; Woodward, Charles E.; Willner, S. P.; Polomski, E. F.; Gehrz, R. D.; Humphreys, Roberta M.; Van Loon, Jacco Th; Ashby, M. L.N.; Eicher, K.; Fazio, G. G.

In: Astrophysical Journal, Vol. 664, No. 2 I, 01.08.2007, p. 850-861.

Research output: Contribution to journalArticle

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AU - Humphreys, Roberta M.

AU - Van Loon, Jacco Th

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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.

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McQuinn KBW, Woodward CE, Willner SP, Polomski EF, Gehrz RD, Humphreys RM et al. The M33 varjable star population revealed by Spitzer. Astrophysical Journal. 2007 Aug 1;664(2 I):850-861. https://doi.org/10.1086/519068