WASP-33: The first delta Scuti exoplanet host star

TL;DR

This paper reports the discovery of delta Scuti-type stellar oscillations in the host star of exoplanet WASP-33 b, marking the first such case among transiting exoplanet hosts, and explores potential star-planet interaction signals.

Contribution

It presents the first detection of delta Scuti variability in a transiting exoplanet host star, expanding understanding of stellar pulsations in exoplanet systems.

Findings

Detected stellar oscillations with ~1 mmag amplitude

Identified a dominant frequency around 21 cycles per day

Possible resonance between stellar pulsations and planetary orbit

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 per day, which is typical of delta 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 delta Sct variability and a very interesting candidate to search for star-planet interactions.