Episodic disk accretion in the halo of the 'old' Pre-Main Sequence cluster Eta Chamaeleontis
arXiv:1011.3816 · doi:10.1111/j.1745-3933.2010.00992.x
Abstract
We present multi-epoch medium-resolution observations of two M4.5 candidate members in the halo of the ~8 Myr Eta Chamaeleontis open cluster. Over six months of observations both stars exhibited variations in their H-alpha line profiles on timescales of days to months, with at least one episode of substantial activity attributable to accretion from a circumstellar disk. We derive an accretion rate ~10^-8.7 Msun/yr for this event, with a rate of ~10^-10.6 Msun/yr in quiescence. Episodic accretion like that observed here means existing surveys of accreting Weak-lined T-Tauri Stars in young clusters are likely incomplete and that gas dissipation timescales calculated from the fraction of accreting objects are underestimates.
5 pages, 5 figures, 1 table. Accepted for publication in MNRAS Letters
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