Three modes of metal-enriched star formation in the early universe

Britton D. Smith, Devin W. Silvia, Matthew J. Turk, Steinn Sigurdsson, Brian W. O'Shea, J. Michael Shull, Michael L. Norman

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


We study how the collapse of gas clouds is altered by the addition of metals by performing a series of simulations of pre-enriched star formation at various metallicities using the adaptive mesh refinement code Enzo. In order to directly compare with the case of metal-free star formation, we use initial conditions identical to the formation of a first star, including only radiation from the high redshift cosmic microwave background (CMB). We find that there were three distinct modes of star formation at high redshift (z > 4): a 'primordial' mode, producing massive stars (10s to 100s M) at very low metallicities (log(Z/Z) < -3.75); a 'CMB-regulated' mode, producing moderate mass (10s of M) stars at high metallicites (log(Z/Z) > -2.5) at redshift z ∼ 15-20); and a 'metallicity-regulated' low-mass (a few M) mode existing between those two metallicities. As the universe ages and the CMB temperature decreases, the range of the low mass mode extends to higher metallicities, eventually becoming the sole mode of star formation. Recent studies have suggested that if dust grains are produced in Pop III supernovae, they can provide an additional coolant during late stages of collapse that could induce additional fragmentation. If this is true, the conventional value of Z cr (∼10-3.5Z) could be as much as two orders of magnitude lower. However, the exact amount of dust created in Pop III supernovae is very uncertain. Even if created in significant amounts, dust can be quickly destroyed via sputtering as dust-rich clumps of outflowing ejecta are impacted by reverse shocks. We report on preliminary results from simulations of dust-destruction in supernova reverse shocks.

Original languageEnglish (US)
Title of host publicationFirst Stars and Galaxies
Subtitle of host publicationChallenges for the Next Decade
Number of pages6
StatePublished - 2010
Event1st Stars and Galaxies: Challenges for the Next Decade - Austin, TX, United States
Duration: Mar 8 2010Mar 11 2010

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


Other1st Stars and Galaxies: Challenges for the Next Decade
Country/TerritoryUnited States
CityAustin, TX

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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