Mass-loss, episodic star formation and the HI envelope of blue compact dwarfs

Free access article

Issue		A&A Volume 434, Number 1, April IV 2005


Page(s)		163 - 165
Section		Galactic structure, stellar clusters and populations
DOI		http://dx.doi.org/10.1051/0004-6361:20041866

A&A 434, 163-165 (2005)
DOI: 10.1051/0004-6361:20041866

Research Note

Mass-loss, episodic star formation and the HI envelope of blue compact dwarfs

H. Kamaya

Department of Astronomy, School of Science, Kyoto University, Sakyo-Ku, 606-8502 Kyoto, Japan
e-mail: kamaya@kusastro.kyoto-u.ac.jp

(Received 20 August 2004 / Accepted 31 January 2005)

Abstract
The star formation history of a class of dwarf galaxies like BCDs (blue compact dwarfs) is episodic and/or intermittent. Episodic star formation is theoretically supported by the limit-cycle model of the interstellar medium (ISM). This model describes the cyclic change among some components of the multi-phased ISM and the total mass of the ISM is conserved. However, the gravitational potential of dwarfs is very shallow. Then, the effect of mass-loss from dwarfs should be examined to investigate the limit-cycle of the ISM. In this paper, we study how the limit-cycle is affected by mass-loss. According to our results, when the time-scale of mass-loss is comparable to the covering time-scale of supernova remnants over a dwarf, the limit-cycle is delayed and an episodic star-formation history is inhibited. Inversely, if the mass-loss is gradual, our model predicts an HI-rich ISM and possible episodic star formation. This prediction is consistent with the typical images of BCDs which are composed of a large amount of HI and on-going star forming regions.

Key words: hydrodynamics -- ISM: structure -- ISM: evolution -- Galaxy: evolution -- ISM: supernova remnants

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