Protostellar Collapse with Various Metallicities

By K. Omukai. 2000

238 citations recorded by the source corpus.

The thermal and chemical evolution of gravitationally collapsing protostellar clouds is investigated, focusing attention on their dependence on metallicity. Calculations are carried out for a range of metallicities spanning the local interstellar value to zero. During the time when clouds are transparent to continuous radiation, the temperatures are higher for those with lower metallicity, reflecting lower radiative ability. However, once the clouds become opaque, in the course of the adiabatic contraction of the transient cores, their evolutionary trajectories in the density-temperature plane converge to a unique curve that is determined by only physical constants. The trajectories coincide with each other thereafter. Consequently, the size of the stellar core at the formation is the same regardless of the gas composition of the parent cloud.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/bdda506e0c6f139cbb2b8c3ff820bb04fdf533a3

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Citations in the corpus

The Fragmentation of Pre-enriched Primordial Objects (2001, background): “Following the collapse to the point where the gas becomes opaque, Omukai (2000) argues that the resulting mass of the protostellar core is independent of metallicity.”
The first stars: formation of binaries and small multiple systems (2009, background): “The resulting metallicity was likely crucial in governing the transition from early highmass star formation to the normal-mass star formation seen today (e.g. Omukai 2000; Bromm et al. 2001; Schneider et al. 2002; Bromm & Loeb 2003; Frebel et al. 2007, 2009; Smith & Sigurdsson 2007).”
The Detectability of the First Stars and Their Cluster Enrichment Signatures (2003, methodology): “Such a massive star formation mode would have continued until the gas metallicity passed a critical threshold of Zcrd10 4 Z (Omukai 2000; Bromm et al. 2001a; Schneider et al. 2002a), which enabled the formation of lower mass clumps and allowed some of the above mechanisms to stop accretion.”
The First Cosmic Structures and Their Effects (2004, methodology): “Using the 1D code described in Omukai (2000), they have studied the fragmentation properties of a gravitationally unstable gas cloud for different initial metallicities in the range 0−1 Z⊙.”
Can Supermassive Black Holes Form in Metal-enriched High-Redshift Protogalaxies? (2008, background): “Cooling by finestructure lines of [C ii] and [O i] is included as in Omukai (2000).”
Two populations of metal-free stars in the early Universe (2006, background): “Once the metallicity of the IGM exceeds a critical level, the formation of primordial, metal-free stars is suppressed and star formation switches to a more conventional mode (e.g. Omukai 2000; Bromm et al. 2001a; Schneider et al. 2002).”
Fluctuations in the high-redshift Lyman–Werner background: close halo pairs as the origin of supermassive black holes (2008, background): “They suggest that gas fragmentation may thus be inevitable above a critical metallicity, whose value is between Zcr ≈ 3 × 10−4Z⊙ (in the absence of dust) and as low as Zcr ≈ 5 × 10−6Z⊙ (with a dust-to-gas mass ratio of about 0.01Z/Z⊙, also see Omukai 2000, Bromm et al. 2001, Schneider et al. 2003).”
Thermal and Fragmentation Properties of Star-forming Clouds in Low-Metallicity Environments (2005, methodology): “Indeed, the temperature evolution converges immediately to a certain trajectory, and variations in the initial conditions affect only the short transient phase of the initial evolution (e.g., Omukai 2000).”
Population III stars: hidden or disappeared? (2007, result): “This idea has been later on expanded and substantiated by a number of detailed studies (Omukai 2000; Bromm et al. 2001; Schneider et al. 2002, 2003).”
Formation and evolution of primordial protostellar systems (2012, background): “Finally, collisional dissociation of H2 removes 4.48 eV of thermal energy per molecule from the gas and substantially offsets the compressional heating up to very high densities (Omukai 2000; Yoshida et al. 2008).”
The First Stars (2003, methodology): “…concept of a critical metallicity, Zcrit, has been used to characterize the transition between Population III and Population II formation modes, where Z denotes the mass fraction contributed by all heavy elements (Omukai 2000; Bromm et al. 2001a; Schneider et al. 2002a, 2003a; Mackey et al. 2003).”
ONE HUNDRED FIRST STARS: PROTOSTELLAR EVOLUTION AND THE FINAL MASSES (2013, methodology): “Here we test this hypothesis using a simple one-zone model, which follows the thermal evolution at the center of the collapsing cloud (e.g., Omukai 2000; Chiaki et al. 2013).”
Formation of the First Stars by Accretion (2003, background): “A metal abundance as low as 10 4 Z can influence the fragmentation mass scale of star-forming clouds (Omukai 2000; Bromm et al. 2001a; Schneider et al. 2002).”
Fragmentation of star-forming clouds enriched with the first dust (2006, methodology): “…of the gas is higher, then the corresponding cooling rate starts to be effective earlier in the evolution of collapsing gas clouds and it is not confined to the highest density regime. therefore sublimate at lower temperatures, 4600 K (Omukai 2000; Schneider et al. 2003; Omukai et al. 2005).”
Formation of Supermassive Black Hole Seeds (2016, background): “In the mean time, gas becomes optically thick to molecular hydrogen cooling and consequently gas temperature rises until the protostar begins to form (Palla et al. 1983; Omukai 2000).”
Is HE 0107–5240 A Primordial Star? The Characteristics of Extremely Metal-Poor Carbon-Rich Stars (2004, background): “−4 (Yoshii & Sabano 1980, see also Omukai 2000) is the primary hurdle facing low mass star formation in the early Universe.”
First Stars, Very Massive Black Holes, and Metals (2001, methodology): “Its physical characteristics are independent of metallicity (n ≈ 1022 cm−3,M ≈ 10−3M⊙; Omukai 2000).”