skip to main content

Title: Radiation magnetohydrodynamic simulations of protostellar collapse: Low-metallicity environments

Among many physical processes involved in star formation, radiation transfer is one of the key processes because it dominantly controls the thermodynamics. Because metallicities control opacities, they are one of the important environmental parameters that affect star formation processes. In this work, I investigate protostellar collapse in solar-metallicity and low-metallicity (Z = 0.1 Z {sub ☉}) environments using three-dimensional radiation hydrodynamic and magnetohydrodynamic simulations. Because radiation cooling in high-density gas is more effective in low-metallicity environments, first cores are colder and have lower entropies. As a result, first cores are smaller, less massive, and have shorter lifetimes in low-metallicity clouds. Therefore, first cores would be less likely to be found in low-metallicity star forming clouds. This also implies that first cores tend to be more gravitationally unstable and susceptible to fragmentation. The evolution and structure of protostellar cores formed after the second collapse weakly depend on metallicities in the spherical and magnetized models, despite the large difference in the metallicities. Because this is due to the change of the heat capacity by dissociation and ionization of hydrogen, it is a general consequence of the second collapse as long as the effects of radiation cooling are not very large during themore » second collapse. On the other hand, the effects of different metallicities are more significant in the rotating models without magnetic fields, because they evolve slower than other models and therefore are more affected by radiation cooling.« less
Authors:
 [1]
  1. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
Publication Date:
OSTI Identifier:
22356960
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 786; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DENSITY; DISSOCIATION; ENTROPY; EVOLUTION; FRAGMENTATION; GRAVITATIONAL COLLAPSE; HYDROGEN; LIFETIME; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; METALLICITY; OPACITY; RADIANT HEAT TRANSFER; SIMULATION; SPECIFIC HEAT; SPHERICAL CONFIGURATION; STARS; THERMODYNAMICS; THREE-DIMENSIONAL CALCULATIONS