Home > Leadership Development Seminars > 5. Self development > Dust Evolution and Population III-II Transition

Dust Evolution and Population III-II Transition

Date: October 28, 2013 15:00-
Place: ES606, ES Building
Speaker:Dr. Daisuke Yamasawa (Tohoku University)

Dust grains are essential for a transition from the massive, first stars (Population III stars, ~ a few * 10 M_sun) to the low-mass, normal stars (Population I/II, ~ 0.1-1.0 M_sun), since the dust grains cool the star-forming gas and cause the low-mass fragmentation resulting in the low-mass star formation. In this talk, I will begin with introductions on the theoretical predictions about Population III stars and on the key physical mechanisms of star formation process in the low-metallicity environment. I will then present the results of our study of the stellar initial mass function (IMF) transition from Population III to Population I/II stars (Pop III-II transition). In this study, we construct a semi-analytic model to clarify the dependence of IMF on dark matter (DM) halo masses and redshifts, using the hierarchical merger trees. We find that Population III stars can form in the massive galaxies with virial temperature T_vir ~ a few * 10^4 K even in the redshift z < 6. Finally, I will discuss the dust properties in the very low-metallicity environment (Z < 10^-4 Z_sun).
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