Kepler-411 Differential Rotation from Three Transiting Planets

TL;DR

This study applies transit spot mapping to Kepler-411 to measure its differential rotation, revealing a solar-like rotation profile with precise shear estimates, based on analysis of 198 detected star spots across three transiting planets.

Contribution

First application of transit spot mapping to determine differential rotation in Kepler-411, providing detailed rotation profile and shear measurement for a star with multiple transiting planets.

Findings

Detected 198 star spots across three planets' transits.

Estimated stellar rotation periods at three latitudes.

Derived a solar-like differential rotation profile with shear of 0.0500 rad/d.

Abstract

The differential rotation of the Sun is a crucial ingredient of the dynamo theory responsible for the generation of its magnetic field. Currently, the rotation profile of a star that hosts one or more transiting planets can be estimated. By detecting the same spot in a later transit, it is possible to infer the stellar rotation period at that latitude. In this work, we apply for the first time transit spot mapping to determine the differential rotation of Kepler-411, a K2V-type star with an average rotation period of 10.52 days, radius of 0.79 R$_\odot$ and mass of 0.83 M$_\odot$. Kepler-411 hosts at least four planets, the inner planet is a super-Earth with a radius of 1.88 R$_\oplus$ and an orbital period of 3.0051 days, whereas the two larger transiting planets are mini Neptunes with radii of 3.27 and 3.31 R$_\oplus$, and periods of 7.834435 and 58.0204 days, respectively. Their orbits are such that they transit the star at latitudes of -11$^{\circ}$, -21$^{\circ}$, and -49$^{\circ}$. Analysis of the transit light curves of the three planets resulted in the detection of a total of 198 spots. For each transit latitude, the rotation period of the star was estimated and the differential rotation pattern estimated independently. Then a solar like differential rotation profile was fit to the three rotation periods at the distinct latitudes, the result agreed extremely well with the previous ones, resulting in a differential shear of $0.0500\pm0.0006$ rd/d or a relative differential rotation of $8.4\pm0.1$\%.