Search and Characterization of Transiting Planets
Planets transiting in front of their parent stars have a special role in the field of extrasolar planets, because their mean density can be measured, allowing the first physical studies of the structure of exoplanets. The transit technique is well suited to search for planets in star clusters, thanks to the availability of wide field imagers. This allows one to study the effects of dynamical environment on planet formation and evolution. We performed multi-site campaigns targeting the most metal-rich open clusters in the Galaxy, NGC 6791 and NGC 6253. For field stars, the frequency of giant planets is strongly correlated with the stellar metallicity. Therefore a significant number of transiting planets is expected in our targets. For NGC 6791, a very populous star cluster, we do not find any planet candidate. The probability that the null detection is simply due to chance coincidence is estimated to be 3%-10%, depending on the metallicity assumed for the cluster. An addional multisite campaign was performed in Summer 2008. Data anlysis is in progress. These additional observations would make a null results significant at more than 99% confidence level.
For NGC 6253, three candidates need confirmation concerning both the planetary nature of the observed transit and the membership to the cluster. The project also contributes to improve our knowledge of the variable stars of these clusters and their surrounding fields. Another project dedicated to search for transiting planets is RATS using the Schmidt Telescope at Cima Ekar.
The telescope is being refurbished for this project will be used for the wide field photometric survey while the 182 Copernico telescope equipped with a fiber fed echelle spectrograph will be used for the spectroscopic follow up. The project is at its first stage and several images of the selected survey stellar fields are under study.
Future activities foresee to exploit the large field of view of OMEGACAM (link alla pagina OMEGACAM) at VST to search for transiting planets in rich stellar fields close to the Galactic plane (Omegatrans).
We are also working at the characterization of transiting planets and their host stars. The first target we studied is HD17156, for which we found spin-orbit alignment.
People: S. Desidera, R. Claudi, R. Gratton, L. Contri, G. Gianesini, G. Martorana, M. Rebeschini, D. Strazzabosco.
Collaboration: G. Piotto, F. De Marchi, V. Granata (Padova Univ.), M. Montalto, R. Saglia (MPE Garching), M. Barbieri (Laboratoire d'Astrophysique de Marseille), E. Poretti (INAF OA Merate), P. Stetson (Victoria, Canada), H. Bruntt, A. Arellano Ferro (UNAM, Mexico) A. Aparicio (IAC), J. Alcala', E. Covino (INAF OA Capodimonte), I. Snellen (Leiden), F. Favata (ESA), S. Scuderi (INAF OA Catania), G. Micela (INAF OA Palermo)
Publications: Barbieri et al. (2008), arXiv 812.0785; Montalto et al. (2007), A&A 470,1137; De Marchi et al. (2007), A&A 471,515