Transit monitoring in the south (TraMoS) project: Discarding transit timing variations in WASP-5b

Abstract

We report nine new transit epochs of the extrasolar planet WASP-5b, observed in the Bessell I band with the Southern Astrophysical Research Telescope at the Cerro Pachon Observatory and with the SMARTS 1 m Telescope at the Cerro Tololo Inter-American Observatory, between 2008 August and 2009 October. The new transits have been combined with all previously published transit data for this planet to provide a new Transit Timing Variation (TTV) analysis of its orbit. We find no evidence of TTV rms variations larger than 1 minute over a 3 year time span. This result discards the presence of planets more massive than about 5 M ⊕, 1 M ⊕, and 2 M ⊕ around the 1:2, 5:3, and 2:1 orbital resonances, respectively. These new detection limits exceed by 5-30 times the limits imposed by current radial velocity observations in the mean motion resonances of this system. Our search for the variation of other parameters, such as orbital inclination and transit depth, also yields negative results over the total time span of the transit observations. This result supports formation theories that predict a paucity of planetary companions to hot Jupiters. © 2012 The American Astronomical Society. All rights reserved.