Supernova dust formation and the grain growth in the early universe: the critical metallicity for low-mass star formation
Date Issued
2015
Author(s)
Chiaki, Gen
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Nozawa, Takaya
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Yoshida, Naoki
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Omukai, Kazuyuki
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Description
We thank Simone Bianchi for his kind contribution. GC is supported by Research Fellowships of the Japan Society for the Promotion of Science (JSPS) for Young Scientists. This work is supported by World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan and in part by Grant-in-Aid for Scientific Research from the JSPS Promotion of Science (22684004, 23224004, 23540324, 25287040, 25287050, and 26400223). A part of calculations is performed with COMA at Center for Computational Sciences in University of Tsukuba. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement n. 306476. ML acknowledges the following funding sources: PRIN INAF 2009 ‘Supernova Variety and Nucleosynthesis Yields’, and PRIN MIUR 2010–2011, project ‘The Chemical and dynamical Evolution of the Milky Way and Local Group Galaxies’, prot. 2010LY5N2T.
Abstract
We investigate the condition for the formation of low-mass second-generation stars in the early Universe. It has been proposed that gas cooling by dust thermal emission can trigger fragmentation of a low-metallicity star-forming gas cloud. In order to determine the critical condition in which dust cooling induces the formation of low-mass stars, we follow the thermal evolution of a collapsing cloud by a one-zone semi-analytic collapse model. Earlier studies assume the dust amount in the local Universe, where all refractory elements are depleted on to grains, and/or assume the constant dust amount during gas collapse. In this paper, we employ the models of dust formation and destruction in early supernovae to derive the realistic dust compositions and size distributions for multiple species as the initial conditions of our collapse calculations. We also follow accretion of heavy elements in the gas phase on to dust grains, i.e. grain growth, during gas contraction. We find that grain growth well alters the fragmentation property of the clouds. The critical conditions can be written by the gas metallicity Zcr and the initial depletion efficiency fdep,0 of gas-phase metal on to grains, or dust-to-metal mass ratio, as (Zcr/10-5.5 Z☉) = (fdep,0/0.18)-0.44 with small scatters in the range of Zcr = [0.06-3.2] × 10-5 Z☉. We also show that the initial dust composition and size distribution are important to determine Zcr.
Volume
446
Issue
3
Start page
2659
Issn Identifier
0035-8711
Ads BibCode
2015MNRAS.446.2659C
Rights
open.access
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