401 research outputs found
The Ultraviolet Morphology of Galaxies
The vacuum ultraviolet offers a unique perspective on galaxy morphology,
stellar populations, and interstellar material which is of particular relevance
to interpreting high redshift galaxies and the history of cosmic star
formation. Here we review UV imaging studies of galaxies since 1990.Comment: 10 pages; tar.gz file includes LaTeX text file, 6 low-resolution
PostScript figures, and 3 style files. For *.ps.gz file with full res
figures, see http://www.astro.virginia.edu/~rwo/ Paper to be published in
"The Ultraviolet Universe at Low and High Redshift" ed. W. H. Waller (AIP
Press) 199
Ultraviolet Radiation from Evolved Stellar Populations: II. The Ultraviolet Upturn Phenomenon in Elliptical Galaxies
We present an analysis of the far-ultraviolet upturn phenomenon (UVX)
observed in elliptical galaxies and spiral galaxy bulges. Our premise is that
the UV radiation from these systems emanates primarily from extreme horizontal
branch (EHB) stars and their progeny. We re-derive the broad-band UV colors
and for globular clusters and elliptical galaxies from the
available satellite data and investigate color-color and color-line strength
correlations. We also provide the ingredients necessary for constructing models
with arbitrary HB morphologies.Comment: uuencoded compressed postscript file, 60pp. (revisions on pp.
7,8,22,33,37 & 57
UV Properties of Galactic Globular Clusters with GALEX II. Integrated colors
We present ultraviolet (UV) integrated colors of 44 Galactic globular
clusters (GGCs) observed with the Galaxy Evolution Explorer (GALEX) in both FUV
and NUV bands. This data-base is the largest homogeneous catalog of UV colors
ever published for stellar systems in our Galaxy. The proximity of GGCs makes
it possible to resolve many individual stars even with the somewhat low spatial
resolution of GALEX. This allows us to determine how the integrated UV colors
are driven by hot stellar populations, primarily horizontal branch stars and
their progeny. The UV colors are found to be correlated with various parameters
commonly used to define the horizontal branch morphology. We also investigate
how the UV colors vary with parameters like metallicity, age, helium abundance
and concentration. We find for the first time that GCs associated with the
Sagittarius dwarf galaxy have (FUV-V) colors systematically redder than GGCs
with the same metallicity. Finally, we speculate about the presence of an
interesting trend, suggesting that the UV color of GCs may be correlated with
the mass of the host galaxy, in the sense that more massive galaxies possess
bluer clusters.Comment: Accepted for publication by The Astronomical Journal. 36 pages, 9
figures, 1 tabl
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