| abstract: |
The origin of cosmic dust is a fundamental issue in planetary science.
I revisit the origin of dust in galaxies, in particular, in the Milky Way
by using a chemical evolution model of a galaxy. This model solves the
time evolution of the amount of four components which are stars,
intestellar medium, 'metal' (elements heavier than helium), and dust.
I first show the shortage of the stellar dust production rate
relative to the dust destruction rate by supernovae. If the dust
growth by material accretion in molecular clouds is active, the observed
dust amount at the solar neighbourhood is reproduced. I analytically
identify the physical mechanism determining the dust content as the balance
between the accretion growth and the supernova destruction. Thus, the dust
content is independent of the stellar dust yield after the accretion growth
becomes active. The timing of the growth activation is determined by the
critical metal mass fraction which depends on the growth and destruction
efficiencies. The solar system formation seems well after the activation
and an enough dust would exist in the proto-solar nebula.
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