Stellar rotational periods in the planet hosting open cluster Praesepe

TL;DR

This study analyzes stellar rotation periods in Praesepe, revealing a strong color-period relation, confirming similar ages with Hyades, and suggesting star-planet interactions may influence stellar rotation in planet-hosting stars.

Contribution

It provides a comprehensive catalog of rotational variables in Praesepe, extending known data for earlier spectral types, and explores potential star-planet interaction effects on stellar rotation.

Findings

Most variables have amplitudes between 0.005 and 0.04 mag.

Rotational periods range from 2.5 to 15 days.

Praesepe and Hyades share the same gyrochronological age.

Abstract

By using the dense coverage of the extrasolar planet survey project HATNet, we Fourier analyze 381 high-probability members of the nearby open cluster Praesepe (Beehive/M44/NGC 2632). In addition to the detection of 10 variables (of \delta Scuti and other types), we identify 180 rotational variables (including the two known planet hosts). This sample increases the number of known rotational variables in this cluster for spectral classes earlier than M by more than a factor of three. These stars closely follow a color/magnitude -- period relation from early F to late K stars. We approximate this relation by polynomials for an easier reference to the rotational characteristics in different colors. The total (peak-to-peak) amplitudes of the large majority (94%) of these variables span the range of 0.005 to 0.04 mag. The periods cover a range from 2.5 to 15 days. These data strongly confirm that Praesepe and the Hyades have the same gyrochronological ages. Regarding the two planet hosts, Pr0211 (the one with the shorter orbital period) has a rotational period that is ~2 days shorter than the one expected from the main rotational pattern in this cluster. This, together with other examples discussed in the paper, may hint that star-planet interaction via tidal dissipation can be significant in some cases in the rotational evolution of stars hosting Hot Jupiters.