We have analyzed JHKL observations of the stellar population of the \approx 9 Myr-old \eta Chamaeleontis cluster .
Using infrared ( IR ) colour-colour and colour-excess diagrams , we find the fraction of stellar systems with near-IR excess emission is 0.60 \pm 0.13 ( 2 \sigma ) .
This results implies considerably longer disc lifetimes than found in some recent studies of other young stellar clusters .
For the classical T Tauri ( CTT ) and weak-lined T Tauri ( WTT ) star population , we also find a strong correlation between the IR excess and H \alpha emission .
The IR excesses of these stars indicate a wide range of star-disc activity ; from a CTT star showing high levels of accretion , to CTT – WTT transition objects with evidence for some on-going accretion , and WTT stars with weak or absent IR excesses .
Of the 15 known cluster members , 4 stars with IR excesses \Delta ( K - L ) > 0.4 mag are likely experiencing on-going accretion owing to strong or variable optical emission .
The resulting accretion fraction ( 0.27 \pm 0.13 ; 2 \sigma ) shows that the accretion phase , in addition to the discs themselves , can endure for at least \sim 10 Myr .