Dust coagulation in star formation with different metallicities |
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| Authors: | Hiroyuki Hirashita Kazuyuki Omukai |
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| Institution: | Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, Taipei 10617, Taiwan;National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan |
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| Abstract: | Dust grains coagulate into larger aggregates in dense gas. This changes their size distribution and possibly affects the thermal evolution of star-forming clouds. We here investigate dust coagulation in collapsing pre-stellar cores with different metallicities by considering the thermal motions of grains. We show that coagulation does occur even at low metallicity ～10?6 Z⊙ . However, we also find (i) that the H2 formation rate on dust grains is reduced only after the majority of H2 is formed and (ii) that the dust opacity is modified only after the core becomes optically thick. Therefore, we conclude that the effects of dust coagulation can safely be neglected in discussing the temperature evolution of the pre-stellar cores for any metallicity as long as the grain motions are thermal. |
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| Keywords: | molecular processes stars: formation ISM: abundances dust extinction galaxies: evolution galaxies: high-redshift |
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