Evolution of newly formed dust in Population III supernova remnants and its impact on the elemental composition of Population II.5 stars

Abstract

We investigate the evolution of dust formed in Population III supernovae (SNe) by considering its transport and processing by sputtering within the SN remnants (SNRs). We find that the fates of dust grains within SNRs heavily depend on their initial radii $a_{\mathrm{ini}}$. For Type II SNRs expanding into the ambient medium with density of $n_{\mathrm{H},0}=1$ cm${}^{-3}$, grains of $a_{\mathrm{ini}}<0.05$ $\mu$m are detained in the shocked hot gas and are completely destroyed, while grains of $a_{\mathrm{ini}}>0.2$ $\mu$m are injected into the surrounding medium without being destroyed significantly. Grains with $a_{\mathrm{ini}}$ = 0.05-0.2 $\mu$m are finally trapped in the dense shell behind the forward shock. We show that the grains piled up in the dense shell enrich the gas up to 10${}^{-6}-10^{-4}$ $Z_{\odot }$, high enough to form low-mass stars with 0.1-1 $M_{\odot }$. In addition, [Fe/H] in the dense shell ranges from -6 to -4.5, which is in good agreement with the ultra-metal-poor stars with [Fe/H] < -4. We suggest that newly formed dust in a Population III SN can have great impacts on the stellar mass and elemental composition of Population II.5 stars formed in the shell of the SNR.

5 pages, 3 figures and 1 table. To appear in the proceedings of IAU Symposium 255 "Low-Metallicity Star Formation: From the First Stars to Dwarf Galaxies", Rapallo, June 2008, eds. L.K. Hunt, S. Madden, & R. Schneider (Cambridge Univ. Press)

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