WASP-33: the firstδScuti exoplanet host star

Abstract

We report the discovery of photometric oscillations in the host star of the exoplanet WASP-33 b (HD 15082). The data were obtained in the R band in both transit and out-of-transit phases from the 0.3-m telescope and the Montcabrer Observatory and the 0.8-m telescope at the Montsec Astronomical Observatory. Proper fitting and subsequent removal of the transit signal reveals stellar photometric variations with a semi-amplitude of about 1 mmag. The detailed analysis of the periodogram yields a structure of significant signals around a frequency of 21 cyc d −1 , which is typical of δ Scuti-type variable stars. An accurate study of the power spectrum reveals a possible commensurability with the planet orbital motion with a factor of 26, but this remains to be confirmed with additional time-series data that will permit the identification of the significant frequencies. These findings make WASP-33 the first transiting exoplanet host star with δ Sct variability and a very interesting candidate to search for star-planet interactions.

pt5m– a 0.5 m robotic telescope on La Palma

“…Our measured inclination matches well with previous studies (Collier Cameron et al 2010;Herrero et al 2011;Smith et al 2011;Kovács et al 2013;von Essen et al 2014), but the planetary radius is found to be up to 3σ larger. This highlights the fact that WASP33b is substantially bloated in comparison to other exoplanets.…”

“…The planet is also observed to be hotter and more bloated than most other exoplanets. In addition, there have been tentative claims of a resonance between the period of orbit and period of pulsations, suggesting a tidal link (Herrero et al 2011).…”

Mass of WASP-33b

“…Herrero et al 2011). It was discovered within the transit survey of the WASP project by Christian et al (2006) to show planet-like transits with a period of 1.22 d. WASP-33b, the first short-period planet of an A-type star, was finally confirmed by Collier Cameron et al (2010, CC10 hereafter).…”

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

“…It is the first planet discovered to orbit an A-type star (Herrero et al 2011). This system has been extensively studied with photometry and spectroscopy (Herrero et al 2011;Moya et al 2011;Smith et al 2011;Deming et al 2012;Sada et al 2012;de Mooij et al 2013;von Essen et al 2014;Hardy et al 2015;Haynes et al 2015;Johnson et al 2015;von Essen et al 2015).…”