A radio survey of older T Tauri stars in the eta Chamaeleontis cluster

A radio continuum survey of X-ray-identified weak-lined T Tauri stars (WTTs ) in the newly-discovered eta Chamaeleontis cluster has been completed usin g the Australia Telescope Compact Array (ATCA). The 10 known WTTs in the cl uster form a unique sample of codistant late-type pre-main-sequence stars w ith ages of similar to 8 Myr and masses ranging from 0.1-1.0 M-.. Our surve y detected none of the 10 X-ray-emitting WTTs with 3 sigma sensitivity limi ts at 4.8 and 8.6 GHz (6.2 and 3.5 cm) of typically 0.4 mJy, corresponding to a radio luminosity of 4.5 x 10(15) erg Hz(-1) s(-1). Rotation periods fo r these stars indicate that they are not, as a group, fast-rotating stars. The non-detection in the radio bands supports the findings of other radio s urveys of inhomogeneous samples of young stars, where radio emission is fai rly common (10-30%) among very young T Tauri stars across all late spectral types, but confined to rapidly-rotating F-G-K stars amongst older zero-age main sequence stars. Rotation, more than youth, appears to be the key to r adio emission in young stars.