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Starspots on WASP-107 and pulsations of WASP-118

Močnik, T.; Hellier, C.; Anderson, D.R.; Clark, B.J.M.; Taylor, J.

Starspots on WASP-107 and pulsations of WASP-118 Thumbnail


Authors

T. Močnik

D.R. Anderson

B.J.M. Clark



Abstract

By analysing the K2 short-cadence photometry, we detect starspot occultation events in the light curve of WASP-107, the host star of a warm-Saturn exoplanet. WASP-107 also shows a rotational modulation with a period of 17.5 ± 1.4 d. Given that the rotational period is nearly three times the planet’s orbital period, one would expect in an aligned system to see starspot occultation events to recur every three transits. The absence of such occultation recurrences suggests a misaligned orbit unless the starspots’ lifetimes are shorter than the star’s rotational period. We also find stellar variability resembling ? Doradus pulsations in the light curve of WASP-118, which hosts an inflated hot Jupiter. The variability is multiperiodic with a variable semi-amplitude of ~200 ppm. In addition to these findings, we use the K2 data to refine the parameters of both systems and report non-detections of transit-timing variations, secondary eclipses and any additional transiting planets. We used the upper limits on the secondary-eclipse depths to estimate upper limits on the planetary geometric albedos of 0.7 for WASP-107b and 0.2 for WASP-118b.

Citation

Močnik, T., Hellier, C., Anderson, D., Clark, B., & Taylor, J. (2017). Starspots on WASP-107 and pulsations of WASP-118. Monthly Notices of the Royal Astronomical Society, 469(2), 1622 - 1629. https://doi.org/10.1093/mnras/stx972

Journal Article Type Article
Acceptance Date Apr 20, 2017
Online Publication Date Apr 25, 2017
Publication Date 2017-08
Publicly Available Date May 26, 2023
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 469
Issue 2
Pages 1622 - 1629
DOI https://doi.org/10.1093/mnras/stx972
Keywords stars, individual, (WASP-107, WASP-118), stars, oscillations, planetary systems, starspots
Publisher URL http://dx.doi.org/10.1093/mnras/stx972

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