Search For Exospheric Signatures From Transiting Planets

We searched for spectral signatures from the exosphere of HD209458 in the UV and the near-IR with UVES and ISAAC at the VLT. We looked in particular for the helium absorption feature at 10 830 \AA predicted to be among the strongest ones. The upper limit of the He I line derived is 0.5% at 3 $\sigma$ for a 3 \AA bandwith. Planet-induced chromospheric activity search on HD209458 was also performed.