Activity and rotation of Kepler-17

Abstract

Magnetic activity on stars manifests itself in the form of dark spots on the stellar surface, that cause modulation of a few percent in the light curve of the star as it rotates. When a planet eclipses its host star, it might cross in front of one of these spots creating a "bump" in the transit light curve. By modelling these spot signatures, it is possible to determine the physical properties of the spots such as size, temperature, and location. In turn, the monitoring of the spots longitude provides estimates of the stellar rotation and differential rotation. This technique was applied to the star Kepler-17, a solar--type star orbited by a hot Jupiter. The model yields the following spot characteristics: average radius of $49\pm 10$ Mm, temperatures of $5100\pm 300$ K, and surface area coverage of $6\pm 4$ \%. The rotation period at the transit latitude, $-5^{\circ }$, occulted by the planet was found to be $11.92\pm 0.05$ d, slightly smaller than the out--of--transit average period of $12.4\pm 0.1$ d. Adopting a solar like differential rotation, we estimated the differential rotation of Kepler-17 to be $\Delta \Omega =0.041\pm 0.005$ rd/d, which is close to the solar value of 0.050 rd/d, and a relative differential rotation of $\Delta \Omega /\Omega =8.0\pm 0.9$ \%. Since Kepler-17 is much more active than our Sun, it appears that for this star larger rotation rate is more effective in the generation of magnetic fields than shear.

9 pages, 11 figures, published in ApJ

References in corpus (12)

• The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations
• Hubble Space Telescope Transmission Spectroscopy of the Exoplanet HD 189733b: High-altitude atmospheric haze in the optical and near-UV with STIS
• The Derivation, Properties and Value of Kepler's Combined Differential Photometric Precision
• The Dependence of Differential Rotation on Temperature and Rotation
• Starspots, spin-orbit misalignment, and active latitudes in the HAT-P-11 exoplanetary system
• Alignment of the stellar spin with the orbits of a three-planet system
• The hot-Jupiter Kepler-17b: discovery, obliquity from stroboscopic starspots, and atmospheric characterization
• Impact of occultations of stellar active regions on transmission spectra: Can occultation of a plage mimic the signature of a blue sky?
• Properties of starspots on CoRoT-2
• Time evolution and rotation of starspots on CoRoT-2 from the modelling of transit photometry
• SOPHIE velocimetry of Kepler transit candidates. V. The three hot Jupiters KOI-135b, KOI-204b and KOI-203b (alias Kepler-17b)
• Starspot activity and rotation of the planet-hosting star Kepler-17

Cited by in corpus (16)

• Temporal Evolution of Spatially-Resolved Individual Star Spots on a Planet-Hosting Solar-type Star: Kepler 17
• Latitudinal differential rotation in the solar analogues 16 Cyg A and B
• Calibration of Differential Light Curves for Physical Analysis of Starspots
• Stellar Magnetic Activity and "Butterfly Diagram" of Kepler-63
• Kepler-411 Differential Rotation from Three Transiting Planets
• Stellar activity and rotation of the planet host Kepler-17 from long-term space-borne photometry
• Superflare UV flashes impact on Kepler-96 system: a glimpse of habitability when the ozone layer first formed on Earth
• Starspot evolution, Differential Rotation and Correlation between Chromospheric and Photospheric Activities on Kepler-411
• Testing the solar activity paradigm in the context of exoplanet transits
• Simulations of starspot anomalies within TESS exoplanetary transit light curves -- I. The detection limits of starspot anomalies in TESS light curves
• The connection between starspots and superflares: a case study of two stars
• Model-free inverse method for transit imaging of stellar surfaces: Using transit surveys to map stellar spot coverage
• Trajectories of Coronal Mass Ejection from Solar-type Stars
• Where does the simplified Stellar Contamination Model fail in Exoplanet Transmission Spectroscopy?
• An investigation of the magnetic activity of HD 134319 based on TESS photometry and ground-based spectroscopy
• Kepler-411 star activity: connection between starspots and superflares