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

¹ Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw, Poland e-mail: udalski@astrouw.edu.pl
² The OGLE Team
³ Observatoire de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
⁴ European Southern Observatory, Casilla 19001, Santiago 19, Chile
⁵ Institut d'Astrophysique de Paris, 98bis Bd Arago, 75014 Paris, France
⁶ Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
⁷ Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, BP 8, Les Trois Lucs, 13376 Marseille Cedex 12, France
⁸ Instituto de Astronomia y Física del Espacio (CONICET-UBA), Buenos Aires, Argentina
⁹ Departamento de Fisica, Astronomy Group, Universidad de Concepción, Casilla 160-C, Concepción, Chile
¹⁰ Department of Astronomy, Universidad de Chile, Santiago, Chile
¹¹ School of Physics and Astronomy, R. and B. Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
¹² Departmento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile
¹³ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK

Received: 26 November 2007
Accepted: 4 February 2008

Abstract

We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in the 2005 season (Campaign #5). About twenty of the 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 a small amplitude of 82 m/s, varying in phase with photometric transit ephemeris. Further analysis confirms the planetary nature of this 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 an F7-8 spectral type dwarf star with a period of 3.68 days. The mass of the planet is equal to 1.03±0.20 M_Jup, while its radius R_Jup. 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 low densities – objects that are a challenge to the current models of exoplanets.