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Paper: The Critical Metallicity for Cosmic Star Formation
Volume: 332, The Fate of the Most Massive Stars
Page: 249
Authors: Schneider, R.
Abstract: Recent theoretical studies consistently predict that the first (Pop III) stars had characteristic masses of 100-600 MSolar, i.e. more than 100 times more massive than those observed today. The basis for this claim is that (i) the fragmentation scale of metal-free clouds is typically 103 MSolar (199; 202); (ii) because of the absence of dust grains the radiative feedback from the forming star is not strong enough to halt the accretion (206); (iii) since accretion rate is as large as 10−2 − 10−3 MSolar/yr, the star grows up to >> 100MSolar within its lifetime (206). A number of indirect evidences seem to favor short-lived, very massive Pop III stars, which include the amplitude and anisotropy of the Near-Infrared Background, (207; 204) and the failure to find any zero-metallicity star in our Galaxy halo (200). On the other hand, observations in the present-day universe show that (Pop II/I) stars form according to a Salpeter initial mass function (IMF) with a characteristic mass of ~ 1MSolar. This situation stimulates some fundamental questions: Has a transition from the early massive star formation mode characterizing Pop III stars to a "normal" one occurred? When did it happen? What physical process caused it?
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