Volume 566, June 2014
|Number of page(s)||4|
|Published online||09 June 2014|
Old pre-main-sequence stars
Disc reformation by Bondi-Hoyle accretion
1 ITAP, Universität zu Kiel, Leibnizstr. 15, 24118 Kiel, Germany
2 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching b. München, Germany
3 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
4 Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany
5 Universitats-Sternwarte München, Scheinerstraße 1, 81679 München, Germany
6 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
Received: 17 February 2014
Accepted: 21 May 2014
Young stars show evidence of accretion discs which evolve quickly and disperse with an e-folding time of ~3 Myr. This is in striking contrast with recent observations that suggest evidence of numerous >30 Myr 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.
Key words: accretion, accretion disks / protoplanetary disks / circumstellar matter / stars: formation / stars: pre-main sequence
© ESO, 2014
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.