Unusual high-frequency oscillations in the KeplerScuti star KIC4840675

Abstract

We show that the star KIC4840675 observed by Kepler is composed of three stars with a rapidly rotating A-type star and two solar-type fainter companions. The A-type star is a δScuti variable with a dominant mode and many other modes of lower amplitude, including several low-frequency variations. The low-frequency variation with highest amplitude can be interpreted as rotational modulation with the light curve changing with time. However, the most interesting aspect of this star is a triplet of independent modes in the range 118-129d-1 (1.4-1.5mHz), which is far outside the range of typical δScuti frequencies. We discuss the possibility that these modes could be solar-like oscillations, oscillations of the roAp type or due to an unseen pulsating compact companion. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.