EDP Sciences
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Volume 388, Number 2, June III 2002
Page(s) 439 - 445
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20020605

A&A 388, 439-445 (2002)
DOI: 10.1051/0004-6361:20020605

Dust-to-gas ratio and star formation history of blue compact dwarf galaxies

H. Hirashita1, Y. Y. Tajiri2 and H. Kamaya2

1  Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, 50125 Firenze, Italy
2  Department of Astronomy, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
    e-mail: tajiri, kamaya@kusastro.kyoto-u.ac.jp

(Received 25 July 2001 / Accepted 29 March 2002 )

This paper investigates the origin of the observed large variety in dust-to-gas ratio, $\cal{D}$, among blue compact dwarf galaxies (BCDs). By applying our chemical evolution model, we find that the dust destruction can largely suppress the dust-to-gas ratio when the metallicity of a BCD reaches $12+\log{\rm (O/H)}\sim 8$, i.e., a typical metallicity level of BCDs. We also show that dust-to-gas ratio is largely varied owing to the change of dust destruction efficiency that has two effects: (i) a significant contribution of Type Ia supernovae to total supernova rate; (ii) variation of gas mass contained in a star-forming region. While mass loss from BCDs was previously thought to be the major cause for the variance of $\cal{D}$, we suggest that the other two effects are also important. We finally discuss the intermittent star formation history, which naturally explains the large dispersion of dust-to-gas ratio among BCDs.

Key words: ISM: dust, extinction -- galaxies: dwarf -- galaxies: evolution -- galaxies: ISM -- stars: formation

Offprint request: H. Hirashita, irasita@arcetri.astro.it

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