PHYSICAL PROPERTIES OF THE 0.94-DAY PERIOD TRANSITING PLANETARY SYSTEM WASP-18
- Astrophysics Group, Keele University, Newcastle-under Lyme, ST5 5BG (United Kingdom)
- Armagh Observatory, College Hill, Armagh, BT61 9DG (United Kingdom)
- SUPA, University of St. Andrews, School of Physics and Astronomy, North Haugh, St. Andrews, KY16 9SS (United Kingdom)
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, 8000 Aarhus C (Denmark)
- Niels Bohr Institute and Centre for Star and Planet Formation, University of Copenhagen, Juliane Maries vej 30, 2100 Copenhagen Oe (Denmark)
- Astronomisches Rechen-Institut, Zentrum fuer Astronomie, Universitaet Heidelberg, Moenchhofstrasse 12-14, 69120 Heidelberg (Germany)
- Dipartimento di Fisica 'E. R. Caianiello', Universita di Salerno, Baronissi (Italy)
- Deutsches SOFIA Institut, NASA Ames Research Center, Mail Stop 211-3, Moffett Field, CA 94035 (United States)
- Institut fuer Astrophysik, Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)
- Institut d'Astrophysique et de Geophysique, Universite de Liege, 4000 Liege (Belgium)
We present high-precision photometry of five consecutive transits of WASP-18, an extrasolar planetary system with one of the shortest orbital periods known. Through the use of telescope defocusing we achieve a photometric precision of 0.47-0.83 mmag per observation over complete transit events. The data are analyzed using the JKTEBOP code and three different sets of stellar evolutionary models. We find the mass and radius of the planet to be M {sub b} = 10.43 +- 0.30 +- 0.24 M {sub Jup} and R {sub b} = 1.165 +- 0.055 +- 0.014 R {sub Jup} (statistical and systematic errors), respectively. The systematic errors in the orbital separation and the stellar and planetary masses, arising from the use of theoretical predictions, are of a similar size to the statistical errors and set a limit on our understanding of the WASP-18 system. We point out that seven of the nine known massive transiting planets (M {sub b} > 3 M {sub Jup}) have eccentric orbits, whereas significant orbital eccentricity has been detected for only four of the 46 less-massive planets. This may indicate that there are two different populations of transiting planets, but could also be explained by observational biases. Further radial velocity observations of low-mass planets will make it possible to choose between these two scenarios.
- OSTI ID:
- 21389330
- Journal Information:
- Astrophysical Journal, Vol. 707, Issue 1; Other Information: DOI: 10.1088/0004-637X/707/1/167; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
THE HOMOGENEOUS STUDY OF TRANSITING SYSTEMS (HoSTS). I. THE PILOT STUDY OF WASP-13
THE SUB-SATURN MASS TRANSITING PLANET HAT-P-12b