Metal abundance range in the Draco dwarf galaxy
The multichannel scanner of the Hale telescope was used to measure the spectral flux distributions of 23 red giants in the Draco system over the range lambda lambda 3240 to 7620. The memberships of these stars in Draco were checked by use of the spectral scans, and for 17 of them the observations are of sufficient quality that estimates of metal abundance can be made. The scans of the Draco stars resemble in every way the scans of red giants in globular clusters. Large differences are seen among the scans of the Draco stars, which are due to a range in Fe/H. The distribution over metal abundance was found from the abundance estimates; its half-width corresponds to an abundance range of a factor of 2.7. The mean metal abundance (Fe/H) = -1.86 +- 0.09, which is larger than the abundance of M92. This result does not support the previous claims that Draco is more metal poor than the most metal-deficient globular clusters. The implications of these results for the interpetations of Draco's color--magnitude diagram and variable star population are discussed. The chemical evolution of Draco was modeled with simple models that assume mass loss and prompt initial enrichment. These models provide adequate fits to the observed abundance distribution, and suggest that the proto-Draco was initially approx. 100 times more massive than Draco is today. 10 figures, 2 tables.
- Research Organization:
- Hale Observatories, Pasadena, CA
- OSTI ID:
- 6311177
- Journal Information:
- Astrophys. J.; (United States), Vol. 225:3
- Country of Publication:
- United States
- Language:
- English
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The chemical inhomogeneity of the Draco dwarf spheroidal galaxy
CARBON ABUNDANCES FOR RED GIANTS IN THE DRACO DWARF SPHEROIDAL GALAXY
Related Subjects
GENERAL PHYSICS
GALACTIC EVOLUTION
MATHEMATICAL MODELS
RED GIANT STARS
CHEMICAL COMPOSITION
SPECTROPHOTOMETRY
GALAXIES
MASS
METALS
PHOTOMETRY
VARIABLE STARS
VISIBLE SPECTRA
ELEMENTS
GIANT STARS
SPECTRA
STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 - Astrophysics & Cosmology- Galaxies