Photometric analyses of abundances in dwarf spheroidal galaxies and globular clusters

Miscellaneous · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6785402

Light, R M

This study investigated the abundance characteristics of several dwarf spheroidal galaxies. The chemical properties of stars in these galaxies are tracers of the origin and evolution of their stellar populations, and thus can provide constraints on the theories of their formation. To derive this abundance information, photometric observations of stars in a sample of globular clusters, covering a large range in metallicity, were analyzed. Parameters describing the position of the red giant branch were found to correlate very well with cluster metallicity over a large range in abundance. These measurements, made in the Thuan-Gunn photometry system, provide ranking schemes which are, with accurate photometry, more sensitive to changes in metallicity than similar broadband BV parameters. The relations were used to derive an improved estimate of the metallicity of cluster NGC 5053. These metallicity relations were used to analyze the Thuan-Gunn system photometry produced for the Sculptor, Ursa Minor, and Carina galaxies. The excellent agreement between their metallicities and those from other previous studies indicates that globular cluster red giant branch parameters are very useful in ranking dwarf spheroidal populations by metallicity. Together with other galaxian data, strong correlations can be seen between the mean metallicities and dispersions in metallicity and the luminosities of the dwarf spheroidal galaxies. These trends also seem to apply to members of the dwarf elliptical class of galaxies. The ramifications that these correlations and the existence of a metallicity gradient in Sculptor have on the formation of the dwarf spheroidals are discussed.

• Research Organization: Yale Univ., New Haven, CT (USA)
• OSTI ID: 6785402
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
GALACTIC EVOLUTION
GALAXIES
CHEMICAL COMPOSITION
SPHERICAL CONFIGURATION
STAR CLUSTERS
CORRELATIONS
ELEMENT ABUNDANCE
LUMINOSITY
MORPHOLOGY
ORIGIN
PHOTOMETRY
RED GIANT STARS
ABUNDANCE
CONFIGURATION
GIANT STARS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
STARS
640105* - Astrophysics & Cosmology- Galaxies