Molecular hydrogen emission from discs in the η Chamaeleontis cluster

Abstract

Discs in the 6 Myr old cluster η Chamaeleontis were searched for emission from hot H2. Around the M3 star ECHA J0843.3-7905, we detect circumstellar gas orbiting at ∼2 au. If the gas is ultraviolet excited, the ro-vibrational line traces a hot gas layer supported by a disc of mass ∼0.03 M⊙, similar to the minimum mass solar nebula. Such a gas reservoir at 6 Myr would promote the formation and the inwards migration of gas giant planets. © 2007 RAS.