VARIABLE ACCRETION IN THE EMBEDDED PHASE OF STAR FORMATION

Journal Article · Sat Oct 10 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/704/1/715· OSTI ID:21367420

Motivated by the recent detection of a large number of embedded young stellar objects (YSOs) with mass accretion rates that are inconsistent with the predictions of the standard model of inside-out collapse, we perform a series on numerical hydrodynamic simulations of the gravitational collapse of molecular cloud cores with various initial masses, rotation rates, and sizes. We focus on the early Class I stage of star formation when circumstellar disks are exposed to high rates of mass deposition from infalling envelopes. Our numerical modeling reproduces the large observed spread in accretion rates inferred for embedded YSOs in Perseus, Serpens, and Ophiuchus star-forming regions by Enoch et al., yielding 37%-75% of objects with 'sub-Shu' accretion rates M-dotapprox<10{sup -6} M-odot yr{sup -1} and 1%-2% of objects with 'super-Shu' accretion rates M-dot>10{sup -5} M-odot yr{sup -1}. Mass accretion rates in the Class I stage have a lognormal distribution, with its shape controlled by disk viscosity and disk temperature. The spread in M-dot is greater in models with lower viscosity and smaller in models with higher viscosity and higher disk temperature, suggesting that gravitational instability may be a dominant cause of the observed diversity in M-dot in embedded YSOs. Our modeling predicts a weak dependence between the mean mass accretion rates and stellar masses in the Class I stage, in sharp contrast to the corresponding steep dependence for evolved T Tauri stars and brown dwarfs.

• OSTI ID: 21367420
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 704; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BINARY STARS
ERUPTIVE VARIABLE STARS
FIELD THEORIES
FLUID MECHANICS
GRAND UNIFIED THEORY
GRAVITATIONAL COLLAPSE
GRAVITATIONAL INSTABILITY
HYDRODYNAMICS
INSTABILITY
MASS
MATHEMATICAL MODELS
MECHANICS
MOTION
PARTICLE MODELS
PLASMA INSTABILITY
PROTOPLANETS
QUANTUM FIELD THEORY
ROTATION
SIMULATION
STANDARD MODEL
STARS
T TAURI STARS
UNIFIED GAUGE MODELS
VARIABLE STARS
VISCOSITY