Episodic disc accretion in the halo of the `old' pre-main-sequence cluster η Chamaeleontis

We present multi-epoch medium-resolution observations of two M4.5 candidate members in the halo of the ∼8 Myr η Chamaeleontis open cluster. During six months of observations, both stars exhibited variations in their Hα line profiles on time-scales of days to months, with at least one episode of substantial activity attributable to accretion from a circumstellar disc. We derive an accretion rate of ∼10^-8.7 M_⊙ yr^-1 for this event, with a rate of ∼10^-10.6 M_⊙ yr^-1 in quiescence. Episodic accretion like that observed here suggests existing surveys of accreting weak-lined T Tauri stars in young clusters are likely incomplete and that gas dissipation time-scales calculated from the fraction of accreting objects are underestimates. This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.