Abstract
view Abstract Citations (224) References (42) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An Interaction Model for the Formation of Dwarf Galaxies and 10 8 Msun Clouds in Spiral Disks Elmegreen, B. G. ; Kaufman, M. ; Thomasson, M. Abstract Galaxy interactions that agitate the interstellar medium by increasing the gas velocity dispersion and removing peripheral gas in tidal arms should lead to the formation and possible ejection of self- gravitationally bound cloud complexes with masses in excess of 10^8^ M_sun_. Some of these complexes may eventually appear as independent dwarf galaxies. The formation of clouds with masses exceeding 10^8^ M_sun_ is the result of gravitational instabilities in gas disks with high velocity dispersions. Such masses and high dispersions were observed with the VLA for the interacting pair IC 2163/NGC 2207, which contains 10 clouds with H I masses > 10^8^ M_sun_ and widespread velocity dispersions 4 times larger than in normal spiral galaxies. A giant cloud that forms by an instability in a high-dispersion ISM should also have a high internal dispersion, and it should produce stars with a greater efficiency than in normal galaxies because of the cloud's greater resistance to self-destruction. Such clouds should also have a larger fraction of massive stars than normal clouds because of the larger temperatures that follow from the high efficiency. Thus agitated galaxies should produce peripheral or nuclear starbursts partly because of their high gas velocity dispersions. Numerical N-body simulations of interacting galaxies illustrate the proposed formation of 10^8^ M_sun_ cloud complexes by gravitational instabilities. The masses and dispersions of the clouds that form increase with the strength of the perturbation. The simulations suggest that the complete detachment of an unbound dwarf galaxy requires a companion mass comparable to or larger than the galaxy mass. Dwarf galaxies that form this way should contain old stars from the original disk plus new stars from the cloud complex/starburst phase of its interaction-induced formation. The model also forms an extended gas pool containing 10^9^ M_sun_ at the end of the tidal arm opposite the companion. This low-density gas was uniformly distributed in the outer part of the disk before the interaction, and it too eventually leaves the galaxy. Publication: The Astrophysical Journal Pub Date: July 1993 DOI: 10.1086/172903 Bibcode: 1993ApJ...412...90E Keywords: Astronomical Models; Dwarf Galaxies; Galactic Evolution; Interacting Galaxies; Interstellar Gas; Spiral Galaxies; H Alpha Line; Many Body Problem; Starburst Galaxies; Very Large Array (Vla); Astrophysics; GALAXIES: INTERACTIONS; GALAXIES: SPIRAL; ISM: CLOUDS full text sources ADS | data products SIMBAD (46) NED (40)
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