Accretion in Gravitationally Contracting Clouds

Abstract

Accretion flow in a contracting magnetized isothermal cloud was studied using magnetohydrodynamical simulations and a nested grid technique. First, the interstellar magnetized cloud experiences a ``runaway collapse'' phase, in which the central density increases drastically within a finite time scale. Finally, it enters an accretion phase, in which inflowing matter accretes onto a central high-density disk or a new-born star. We found that the accretion rate reaches (4 -- 40) $\times c_s^3/G$, where $c_s$ and $G$ represent the isothermal sound speed and the gravitational constant, respectively. This is much larger than the standard accretion rate of $0.975c_s^3/G$ for a hydrostatic isothermal spherical cloud (Shu 1977, AAA19.065.044). Due to the effect of an extra infall velocity achieved in the runaway phase ($\sim 2c_s$), the accretion rate is boosted. This rate declines with time in contrast to Shu's solution, but keeps $\gtsim 2.5 c_s^3/G$. The observed gas infall rate around proto-stars such as L1551 IRS 5 and HL Tau is also discussed.

10 pages, latex using PASJ style file (available from http://www.tenmon.or.jp/pasj/index-e.html), postscripted text and figures are available from http://quasar.ed.niigata-u.ac.jp/docs/Papers/mag3ps.tgz

Cited by in corpus (18)

• Control of star formation by supersonic turbulence
• The Burst Mode of Protostellar Accretion
• The Physics of Star Formation
• Formation of the First Stars by Accretion
• Collapse-Driven Outflow in Star-Forming Molecular Cores
• Evolution of Angular Momentum Distribution during Star Formation
• Constraints on the Formation and Evolution of Circumstellar Disks in Rotating Magnetized Cloud Cores
• Protostellar mass accretion rates from gravoturbulent fragmentation
• Dynamical Collapse of Nonrotating Magnetic Molecular Cloud Cores: Evolution Through Point-Mass Formation
• The Formation of Stellar Clusters: Time Varying Protostellar Accretion Rates
• Magnetically Controlled Spasmodic Accretion During Star Formation. I. Formulation of the Problem and Method of Solution
• Early evolution of disk, outflow, and magnetic field of young stellar objects: Impact of dust model
• Formation of an Infalling Disklike Envelope around a Protostar
• The seeds of supermassive black holes and the role of local radiation and metal spreading
• ALMA Observations toward the S-shaped Outflow and the Envelope around NGC1333 IRAS 4A2
• Self-Gravitating Magnetically-Supported Protostellar Disks and the Formation of Substellar Companions
• Discovery of Asymmetric Spike-like Structures of the 10 au Disk around the Very Low-luminosity Protostar Embedded in the Taurus Dense Core MC 27/L1521F with ALMA
• Environmental Effects of Star-Forming Cores on Mass Accretion Rate