Condition for low-mass star formation in shock-compressed metal-poor clouds

Daisuke Nakauchi, Kazuyuki Omukai, Raffaella Schneider

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Shocks may have been prevalent in the early Universe, associated with virialization and supernova explosions, etc. Here, we study thermal evolution and fragmentation of shockcompressed clouds, by using a one-zone model with detailed thermal and chemical processes. We explore a large range of initial density (1-105 cm-3), metallicity (0-10-2 Z), UV strength (0-500 times Galactic value), and cosmic microwave background temperature (10 and 30 K). Shock-compressed clouds contract isobarically via atomic and molecular line cooling, until self-gravitating clumps are formed by fragmentation. If the metals are only in the gas-phase, the clump mass is higher than ~3M in any conditions we studied. Although in some cases with a metallicity higher than ~10-3 Z, re-fragmentation of a clump is caused by metal-line cooling, this fragment mass is higher than ~30M. On the other hand, if about half the mass of metals is condensed in dust grains, as in the Galactic interstellar medium, dust cooling triggers re-fragmentation of a clump into subsolar mass pieces, for metallicities higher than ~10-5 Z. Therefore, the presence of dust is essential in low-mass (≳ M) star formation from a shock-compressed cloud.

Original languageEnglish
Pages (from-to)1043-1056
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 2018


  • Stars: Population II
  • Stars: Population III
  • Stars: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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