Formation of massive stars under protostellar radiation feedback: Very metal-poor stars

Hajime Fukushima, Takashi Hosokawa, Gen Chiaki, Kazuyuki Omukai, Naoki Yoshida, Rolf Kuiper

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


We study the formation of very metal-poor stars under protostellar radiative feedback effect. We use cosmological simulations to identify low-mass dark matter haloes and star-forming gas clouds within them. We then follow protostar formation and the subsequent long-term mass accretion phase of over one million years using two-dimensional radiation-hydrodynamics simulations. We show that the critical physical process that sets the final mass is the formation and expansion of a bipolar H ii region. The process is similar to the formation of massive primordial stars, but radiation pressure exerted on dust grains also contributes to halting the accretion flow in the low-metallicity case. We find that the net feedback effect in the case with metallicity Z = 10-2 Z⊙ is stronger than in the case with Z ∼1 Z⊙. With decreasing metallicity, the radiation-pressure effect becomes weaker, but photoionization heating of the circumstellar gas is more efficient owing to the reduced dust attenuation. In the case with Z = 10-2 Z⊙, the central star grows as massive as 200 solar masses, similarly to the case of primordial star formation. We conclude that metal-poor stars with a few hundred solar masses can be formed by gas accretion despite the strong radiative feedback.

Original languageEnglish
Pages (from-to)829-845
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 2020 Sept 1


  • accretion, accretion discs
  • cosmology: theory
  • stars: Population II
  • stars: formation
  • stars: massive

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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