Resumo

SIGALOTTI, L. Di G. Rev. mex. fis. [online]. 2006, vol.52, suppl.3, pp.5-8. ISSN 0035-001X.

We follow the spherical gravitational collapse and the subsequent accretion phase of nonsingular A = 0.2 logatropes of both subcritical and critical masses using numerical hydrodynamics. The initial configuration is close to hydrostatic equilibrium. In all cases, we assume fiducial values of the central temperature (T_c = 10 K) and surface pressure (p_s/k = 1.3 x 10⁵ cm^-3 K) that are appropriate for star formation in isolated environments. We find that immediately after the transition toward a singular density profile, the mass accretion rate increases abruptly in a very short timescale followed by a phase of much slower increase, after which a peak value of M_acc is reached. At this point about 40% of total mass has been accreted by the central protostar. Thereafter, the accretion rate declines for the remainder of the evolution until 100% of the total core mass is condensed into a form of stellar mass. The results predict peak values of M_acc as high as ~ 5 - 6 x 10^-5 M_Θ yr ^-1 for logatropes close to the critical mass and imply that stars of mass 1 M_Θ < M_* < 92 M_Θ all form within 3.6-6.6 x 10⁶ years. The models are representative of the early protostellar phase from Class 0 to Class I objects.

Palavras-chave : Hydrodynamics; star formation; accretion and accretion disks.

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