We conjecture that observed protoplanetary disc accretion rates may be explained with low viscosities, which could be the result of hydrodynamic turbulence. We show that viscosities parametrized in the usual way with alpha greater than or similar to 10(-4), comparable to values suggested for hydrodynamic turbulence, can explain the observed accretion rates and lifetimes with plausible inner disc surface densities. Our models are also in better agreement with surface density estimates of the minimum mass solar nebula than models with rapid transport for a given mass accretion rate, such as recent models of accretion driven by magnetic winds. The required surface densities are a natural result of the protostellar infall phase, as long as non-gravitational transport is limited. We argue that, in addition to possible non-ideal magnetic transport due to disc winds possibly modified by the Hall effect, the effects of low-viscosity hydrodynamic accretion deserve more consideration.
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UNIV LONDON QUEEN MARY & WESTFIELD COLL,SCH MATH SCI,LONDON E1 4NS,ENGLANDUNIV LONDON QUEEN MARY & WESTFIELD COLL,SCH MATH SCI,LONDON E1 4NS,ENGLAND
Armitage, PJ
Clarke, CJ
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UNIV LONDON QUEEN MARY & WESTFIELD COLL,SCH MATH SCI,LONDON E1 4NS,ENGLANDUNIV LONDON QUEEN MARY & WESTFIELD COLL,SCH MATH SCI,LONDON E1 4NS,ENGLAND
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Cornell Univ, Ctr Astrophys & Planetary Sci, Dept Astron, Ithaca, NY 14853 USACornell Univ, Ctr Astrophys & Planetary Sci, Dept Astron, Ithaca, NY 14853 USA
Li, Rixin
Chen, Yi-Xian
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Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA
Tsinghua Univ, Dept Phys, Beijing 100084, Peoples R ChinaCornell Univ, Ctr Astrophys & Planetary Sci, Dept Astron, Ithaca, NY 14853 USA
Chen, Yi-Xian
Lin, Douglas N. C.
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Univ Calif Santa Cruz, Dept Astron, Santa Cruz, CA 95064 USA
Tsinghua Univ, Inst Adv Studies, Beijing 100084, Peoples R ChinaCornell Univ, Ctr Astrophys & Planetary Sci, Dept Astron, Ithaca, NY 14853 USA