SIMBAD references

2014MNRAS.445.1186L - Mon. Not. R. Astron. Soc., 445, 1186-1204 (2014/December-1)

General polytropic Larson-Penston-type collapses.

LOU Y.-Q. and SHI C.-H.

Abstract (from CDS):

We investigate self-similar hydrodynamics of a general polytropic (GP) gas with spherical symmetry under self-gravity and extend the conventional polytropic (CP) relation n = 2 - γ for the self-similar index n and the polytropic index γ to a general relation n = 2(q + γ - 2)/(3q - 2), where q is a real parameter by specific entropy conservation along streamlines. We derive GP Larson-Penston (LP)-type solutions for q > 2/3 and γ > 4/3; Larson-Penston-Hunter (LPH)-type solutions are also constructed in a GP gas by a time-reversal operation on a GP-LP-type solution and by connecting to a GP free-fall-type solution across t = 0. These GP-LPH solutions describe dynamic processes that a GP gas globule, static and dense initially, undergoes a runaway collapse under self-gravity, forms a central mass singularity, and keeps accreting during a free-fall stage. We apply such GP-LPH-type solutions with variable envelope mass infall rates (EMIRs) for the dynamic evolution of globules and dense cores in star-forming molecular clouds. In particular, a GP-LPH-type solution can sustain an EMIR as low as 10–8 ∼ 10–6M/yr or even lower - much lower than that of Shu's isothermal model for a cloud core in Class 0 and Class I phases. Such GP-LPH-type solutions with EMIRs as low as 10–9 ∼ 10–8M/yr offer a sensible viable mechanism of forming brown dwarfs during the accretion stage in a collapsed GP globules with 1.495 ≤ γ ≤ 1.50 and 0.99 ≤ n ≤ 1.0. The GP-LPH solutions with 0.94 < n < 0.99 and 1.47 < γ < 1.495 can even give extremely low EMIRs of 10–12 ∼ 10–9M/yr to form gaseous planet-type objects in mini gas globules.

Abstract Copyright: © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2014)

Journal keyword(s): hydrodynamics - planets and satellites: formation - planets and satellites: gaseous planets - brown dwarfs - stars: formation - ISM: clouds

Simbad objects: 3

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