AAS 203rd Meeting, January 2004
Session 49 Stars Looking Forward to Retirement
Poster, Tuesday, January 6, 2004, 9:20am-6:30pm, Grand Hall
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[49.01] Narrow-Band Photometry of Red Supergiants in the Small Magellanic Cloud
R.F. Wing, K.M. Walker (OSU), E. Costa (U. de Chile), M.L. Houdashelt (JHU), D.J. MacConnell (CSC/STScI)
A set of 36 red supergiants belonging to the Small
Magellanic Cloud have been observed on a six-color
narrow-band photometric system that measures continuum
points and bands of TiO and CN, all in the near-infrared.
The TiO--based spectral types range from The absolute magnitudes MV and M(104), based on a
distance modulus of 18.9 mag and a very small correction for
interstellar absorption, imply that the stars observed are
Ia and Iab supergiants. Their CN--based luminosity classes,
however, are mostly Ib. The difference is attributed to the
effect of the lower metallicity of the SMC, relative to the
Population I stars of the Milky Way, on the observed CN
strength. These observations allow us to express the
CN/luminosity calibration as a function of metallicity,
thereby enhancing the usefulness of red supergiants as
distance indicators for nearby galaxies of known
metallicity.
The observations were made at Cerro Tololo Inter-American
Observatory.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.