2014A&A...566L...3S -
Astronomy and Astrophysics, volume 566, L3-3 (2014/6-1)
Old pre-main-sequence stars. Disc reformation by Bondi-Hoyle accretion.
SCICLUNA P., ROSOTTI G., DALE J.E. and TESTI L.
Abstract (from CDS):
Young stars show evidence of accretion discs which evolve quickly and disperse with an e-folding time of ∼3Myr. This is in striking contrast with recent observations that suggest evidence of numerous >30Myr old stars with an accretion disc in large star-forming complexes. We consider whether these observations of apparently old accretors could be explained by invoking Bondi-Hoyle accretion to rebuild a new disc around these stars during passage through a clumpy molecular cloud. We combine a simple Monte Carlo model to explore the capture of mass by such systems with a viscous evolution model to infer the levels of accretion that would be observed. We find that a significant fraction of stars may capture enough material via the Bondi-Hoyle mechanism to rebuild a disc of mass >1 minimum-mass solar nebula, and ≲10% accrete at observable levels at any given time. A significant fraction of the observed old accretors may be explained with our proposed mechanism. Such accretion may provide a chance for a second epoch of planet formation, and have unpredictable consequences for planetary evolution.
Abstract Copyright:
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Journal keyword(s):
accretion, accretion disks - protoplanetary disks - circumstellar matter - stars: formation - stars: pre-main sequence
Simbad objects:
4
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