OGLE-TR-211 - a new transiting inflated hot Jupiter from the OGLE survey and ESO LP666 spectroscopic follow-up program

We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in 2005 season (Campaign #5). About twenty most promising candidates discovered in these data were subsequently verified spectroscopically with the VLT/FLAMES spectrograph. One of the candidates, OGLE-TR-211, reveals clear changes of radial velocity with small amplitude of 82 m/sec, varying in phase with photometric transit ephemeris. Thus, we confirm the planetary nature of the OGLE-TR-211 system. Follow-up precise photometry of OGLE-TR-211 with VLT/FORS together with radial velocity spectroscopy supplemented with high resolution, high S/N VLT/UVES spectra allowed us to derive parameters of the planet and host star. OGLE-TR-211b is a hot Jupiter orbiting a F7-8 spectral type dwarf star with the period of 3.68 days. The mass of the planet is equal to 1.03±0.20 MJup while its radius 1.36 +0.18 −0.09 RJup. The radius is about 20% larger than the typical radius of hot Jupiters of similar mass. OGLE-TR-211b is, then, another example of inflated hot Jupiters – a small group of seven exoplanets with large radii and unusually small densities – objects being a challenge to the current models of exoplanets.The OGLE project is partially supported by the Polish MNiSW grant N20303032/4275. WG, DM, GP, MTR and MZ gratefully acknowledge support for this work from the chilean FONDAP Center of Astrophysics 15010003. NCS acknowledges the support from Fundac¸ ˜ao para a Ciˆencia e a Tecnologia, Portugal, in the form of a grant (reference POCI/CTE-AST/56453/2004), and support by the EC’s FP6 and by FCT (with POCI2010 and FEDER funds), within the HELAS international collaboration