The Impact of Feedback in Massive Star Formation. II. Lower Star Formation Efficiency at Lower Metallicity
Artikel i vetenskaplig tidskrift, 2018

We conduct a theoretical study of the formation of massive stars over a wide range of metallicities from 10-5to and evaluate the star formation efficiencies (SFEs) from prestellar cloud cores taking into account multiple feedback processes. Unlike for simple spherical accretion, feedback processes in the case of disk accretion do not set upper limits on stellar masses. At solar metallicity, launching of magneto-centrifugally driven outflows is the dominant feedback process to set SFEs, while radiation pressure, which has been regarded as pivotal, makes only a minor contribution even in the formation of stars over 100 M⊙. Photoevaporation becomes significant in the formation of stars over 20 M⊙at low metallicities of ≲ 10-2Z⊙, where dust absorption of ionizing photons is inefficient. We conclude that if initial prestellar core properties are similar, then massive stars are rarer in extremely metal-poor environments of 10-5-10-3Z⊙. Our results give new insight into the high-mass end of the initial mass function and its potential variation with galactic and cosmological environments.

stars: formation


stars: evolution

stars: luminosity function

mass function

stars: massive

stars: winds


Kei E.I. Tanaka

University of Florida

National Astronomical Observatory of Japan

Osaka University

Jonathan Tan

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

University of Virginia

Yichen Zhang


Takashi Hosokawa

Kyoto University

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 861 1 68


Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik

Annan fysik



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