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Author Gallagher, J. S. III ♦ Hunter, D. A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ GALACTIC EVOLUTION ♦ BALMER LINES ♦ MAGELLANIC CLOUDS ♦ MORPHOLOGY ♦ PHOTOMETRY ♦ SPATIAL DISTRIBUTION ♦ SPIRAL CONFIGURATION ♦ STAR EVOLUTION ♦ CONFIGURATION ♦ DISTRIBUTION ♦ GALAXIES ♦ Astrophysics & Cosmology- Galaxies
Abstract UBVRI and H-alpha photometric observations are presented for 16 amorphous galaxies and a comparison sample of Magellanic irregular (Im) and Sc spiral galaxies. These data are analyzed in terms of star-formation rates and histories in amorphous galaxies. Amorphous galaxies have mean global colors and star-formation rates per unit area that are similar to those in giant Im systems, despite differences in spatial distributions of star-forming centers in these two galactic structural classes. Amorphous galaxies differ from giant Im systems in having somewhat wider scatter in relationships between B - V and U - B colors, and between U - B and L(H-alpha)/L(B). This scatter is interpreted as resulting from rapid variations in star-formation rates during the recent past, which could be a natural consequence of the concentration of star-forming activity into centrally located, supergiant young stellar complexes in many amorphous galaxies. While the unusual spatial distribution and intensity of star formation in some amorphous galaxies is due to interactions with other galaxies, several amorphous galaxies are relatively isolated and thus the processes must be internal. The ultimate evolutionary fate of rapidly evolving amorphous galaxies remains unknown. 77 references.
Educational Use Research
Learning Resource Type Article
Publisher Date 1987-07-01
Publisher Place United States
Journal Astron. J.
Volume Number 94
Organization Lowell Observatory, Flagstaff, AZ


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