STARSPOTS, SPIN–ORBIT MISALIGNMENT, AND ACTIVE LATITUDES IN THE HAT-P-11 EXOPLANETARY SYSTEM

By Roberto Sanchis-Ojeda, J. Winn. 2011

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We present the analysis of four months of Kepler photometry of the K4V star HAT-P-11, including 26 transits of its “super-Neptune” planet. The transit data exhibit numerous anomalies which we interpret as passages of the planet over dark starspots. These spot-crossing anomalies preferentially occur at two specific phases of the transit. These phases can be understood as the intersection points between the transit chord and the active latitudes of the host star, where starspots are most abundant. Based on the measured characteristics of spot-crossing anomalies and previous observations of the Rossiter–McLaughlin effect, we find two solutions for the stellar obliquity ψ and active latitude l: either ψ = 106+15−11 and l = 19.7+1.5−2.2, or ψ = 97+8−4 and l = 67+2−4 (all in degrees). If the active latitude changes with time analogous to the “butterfly diagram” of the Sun's activity cycle, future observations should reveal changes in the preferred phases of spot-crossing anomalies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5d7bce116242fb8df2d6a5e447458add8d7aed73

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Citations in the corpus

• The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets (2017, background): “…event is larger than the observational uncertainty, thus enabling the parameters of the photospheric heterogeneity to be modeled (e.g., Sanchis-Ojeda & Winn 2011; Huitson et al. 2013; Pont et al. 2013; Tregloan-Reed et al. 2013; Scandariato et al. 2017) or the affected portion of the…”
• ON THE FORMATION OF HOT JUPITERS IN STELLAR BINARIES (2012, methodology): “The projection of ψ onto the plane of the sky, λ, can be observed through the Rossiter–McLaughlin effect (e.g., Gaudi & Winn 2007) and other methods (e.g., Nutzman et al. 2011; Sanchis-Ojeda & Winn 2011; Shporer et al. 2012).”