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Earth Planets Space, Vol. 65 (No. 3), pp. 213-222, 2013
doi:10.5047/eps.2012.04.014
Ryosuke S. Asano1, Tsutomu T. Takeuchi1, Hiroyuki Hirashita2, and Akio K. Inoue3
1Department of Particle and Astrophysical Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
2Academia Sinica Institute for Astronomy and Astrophysics, P. O. Box 23-141, Taipei 10617, Taiwan
3College of General Education, Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530, Japan
(Received November 7, 2011; Revised April 22, 2012; Accepted April 27, 2012; Online published March 12, 2013)
Abstract:
This paper investigates the main driver of
dust mass growth in the interstellar medium (ISM) by using a
chemical evolution model of a galaxy with metals (elements heavier
than helium) in the dust phase, in addition to the total amount of
metals. We consider asymptotic giant branch (AGB) stars, type II
supernovae (Sne II), and dust mass growth in the ISM, as the
sources of dust, and SN shocks as the destruction mechanism of
dust. Furthermore, to describe the dust evolution precisely, our model
takes into account the age and metallicity (the ratio of metal mass
to ISM mass) dependence of the sources of dust. We have particularly
focused on the dust mass growth, and found that in the ISM this is regulated by the metallicity. To quantify this
aspect, we introduce a "critical metallicity", which is the
metallicity at which the contribution of stars (AGB stars and
Sne II) equals that of the dust mass growth in the ISM. If the
star-formation timescale is shorter, the value of the critical
metallicity is higher, but the galactic age at which the
metallicity reaches the critical metallicity is shorter. From
observations, it was expected that the dust mass growth was the
dominant source of dust in the Milky Way and dusty QSOs at high
redshifts. By introducing a critical metallicity, it is clearly
shown that the dust mass growth is the main source of dust in such
galaxies with various star-formation timescales and ages. The dust
mass growth in the ISM is regulated by metallicity, and we emphasize
that the critical metallicity serves as an indicator to judge
whether the grain growth in the ISM is the dominant source of dust in a
galaxy, especially because of the strong, and nonlinear, dependence
on the metallicity.
Key words:
Dust, extinction, galaxies: infrared, galaxies:
evolution, galaxies: starburst, stars: formation.