Query : 2002A&A...395..321S

2002A&A...395..321S - Astronomy and Astrophysics, volume 395, 321-338 (2002/11-3)

Gravitational collapse of nonsingular logatropic spheres.


Abstract (from CDS):

We present the results of high-resolved, hydrodynamic calculations of the spherical gravitational collapse and subsequent accretion of nonsingular subcritical and critical A=0.2 logatropes, starting with initial configurations close to hydrostatic equilibrium. Two sequences of models with varying masses and the same central temperature Tc=10K are defined, which differ only in the fiducial value of the truncation pressure (ps/k=1.3x105cm–3K and 1.0x107cm–3K). In all cases, we follow the calculations until the central protostar has accreted 99% of the total available mass. Thus, the models may be indicative of early evolution from the Class 0 to the Class I protostellar phase. We find that the approach to the singular density profile is never entirely subsonic. In the lower ps sequence, about 6% of the mass collapses supersonically in a 1M sphere, while only ∼0.02% behaves this way in a critical (≃92.05M) logatrope. In the high ps sequence the same trend is observed, with ∼0.7% of the mass now infalling supersonically at the time of singularity formation in a 1M sphere. Immediately after singularity formation, the accretion rate rises steeply in all cases, reaching a maximum value when the central protostar has accreted ∼40% of its final mass. Thereafter, it decreases monotonically for the remainder of the evolution. Our models predict peak values of {dot}(M)acc as high as ∼5-6x10–5M/yr for logatropes close to the critical mass. In contrast, a subcritical 1M logatrope reaches a maximum value of ∼8x10–7M/yr for the lower ps sequence compared to ∼5x10–6M/yr for the higher ps case. The results also imply that the accretion lifetimes are longer in logatropes with lower ps, consistent with the observational evidence that star formation in clumped regions occurs on shorter timescales compared to more isolated environments.

Abstract Copyright:

Journal keyword(s): hydrodynamics - methods: numerical - stars: formation - circumstellar matter

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4136 0
2 LDN 1544 DNe 05 04 16.6 +25 10 48           ~ 812 0
3 NAME [BM89] L1544 cor 05 04 22.5 +25 11 36           ~ 436 1
4 LDN 57 DNe 17 22 38.2 -23 49 34           ~ 304 1

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