2012/08/01 by Takaya Nozawa, Takashi Kozasa, Ken'ichi Nomoto +1 · 1 citation
Physics and Astronomy · #Accretion (finance) #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Fragmentation (computing) #Grain growth #Grain size #Materials science #Metallicity #Metallurgy #Physics #Star formation #Stars #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1088/2041-8205/756/2/l35
5 pages, 4 figures, 1 table, Accepted for publication in ApJ Letters
arxiv created 2012/08/01 · openalex publication_date 2012/08/23 · arxiv updated 2015/06/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
The discovery of a low-mass star with such a low metallicity as ⩽4.5 × 10 −5 Z ☉ reveals the critical role of dust in the formation of extremely metal-poor stars. In this Letter, we explore the effect of the growth of dust grains through accretion of gaseous refractory elements in very low metallicity pre-stellar cores on cloud fragmentation induced by dust emission cooling. Employing a simple model of grain growth in a gravitationally collapsing gas, we show that Fe and Si grains can grow efficiently at hydrogen densities of ≃ 10 10 –10 14 cm −3 in the clouds with metal abundances of −5 ≲ [Fe, Si/H] ≲ −3. The critical metal number abundances, above which the grain growth could induce the fragmentation of the gas clouds, are estimated to be A crit ≃ 10 −9 –10 −8 , unless the initial grain radius is too large (≳1 μm) or the sticking probability is too small (≲0.01). We find that even if the initial dust-to-gas mass ratio is well below the minimum value required for the dust-induced fragmentation, the grain growth increases the dust mass high enough to cause the gas to fragment into sub-solar mass clumps. We suggest that as long as the critical metal abundance is satisfied, grain growth could play an important role in the formation of low-mass stars with metallicity as low as 10 −5 Z ☉ .