Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published February 20, 2017 | Published + Accepted Version
Journal Article Open

Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System


Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet's atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ~350 hr of 4.5 μm observations with the Spitzer Space Telescope. The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b's 4.5 μm photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet's orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

Additional Information

© 2017 The American Astronomical Society. Received 2016 December 14; revised 2017 January 11; accepted 2017 January 12; published 2017 February 14. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Support for this work was provided by JPL/Caltech. J.d.W. was further supported by the WBI (Wallonie-Bruxelles International) under the WBI-World Excellence Fellowship Program. A.S. performed this work in part under contract with the California Institute of Technology (Caltech) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. V.A. is funded by the Stellar Astrophysics Centre via the Danish National Research Foundation (grant DNRF106). The research was supported by the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (grant agreement No. 267864). Radial velocity data presented herein were obtained at the W. M. Keck Observatory using time granted by the California Institute of Technology, UC Berkeley, and the University of Hawaii. We thank the observers who contributed to the measurements reported here and acknowledge the efforts of the Keck Observatory staff. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. J.d.W thanks T. Rogers, V. Stamenković A. Zsom, B.-O. Demory, M. Gillon, S. Seager, and V. Van Grootel for useful discussions during the preparation of this manuscript.

Attached Files

Published - Wit_2017_ApJL_836_L17.pdf

Accepted Version - 1702.03797.pdf


Files (2.6 MB)
Name Size Download all
1.3 MB Preview Download
1.4 MB Preview Download

Additional details

August 19, 2023
February 2, 2024