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

Author(s): de Wit, Julien; Lewis, Nikole K; Knutson, Heather A.; Fuller, Jim; Antoci, Victoria; et al

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Abstract: 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-2ʼs eccentric planetary system gained from the analysis of∼350 hr of 4.5μm 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 4.5μm 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-2ʼs pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.
Publication Date: 20-Feb-2017
Electronic Publication Date: 14-Feb-2017
Citation: de Wit, Julien, Lewis, Nikole K, Knutson, Heather A, Fuller, Jim, Antoci, Victoria, Fulton, Benjamin J, Laughlin, Gregory, Deming, Drake, Shporer, Avi, Batygin, Konstantin, Cowan, Nicolas B, Agol, Eric, Burrows, Adam S, Fortney, Jonathan J, Langton, Jonathan, Showman, Adam P. (2017). Planet-induced Stellar Pulsations in HAT-P-2’s Eccentric System. \apj, 836 (L17 - L17. doi:10.3847/2041-8213/836/2/L17
DOI: doi:10.3847/2041-8213/836/2/L17
Type of Material: Journal Article
Journal/Proceeding Title: Astrophysical Journal Letters
Version: Author's manuscript

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