Asteroseismology of the Multiplanet System K2-93

TL;DR

This paper uses asteroseismology with new K2 data to precisely characterize the host star of the K2-93 multiplanet system, refining the orbital periods and stellar parameters of its five planets for future atmospheric studies.

Contribution

It provides the first detailed asteroseismic analysis of K2-93, improving stellar and planetary parameter estimates and constraining the orbital periods of the outer planets.

Findings

Stellar mass estimated at 1.22 solar masses.

Stellar radius determined to be 1.30 solar radii.

Orbital periods of outer planets constrained.

Abstract

We revisit the analysis of the bright multiplanet system K2-93, discovered with data taken by the K2 mission. This system contains five identified planets ranging in size from sub-Neptune to Jupiter size. The K2 data available at the discovery of the system only showed single transits for the three outer planets, which allowed weak constraints to be put on their periods. As these planets are interesting candidates for future atmospheric studies, a better characterization of the host star and tighter constraints on their orbital periods are essential. Using new data from the K2 mission taken after the discovery of the system, we perform an asteroseismic characterization of the host star. We are able to place strong constraints on the stellar parameters and obtain a value for the stellar mass of $1.22^{+0.03}_{-0.02}\, \rm M_{\odot}$, a stellar radius of $1.30\pm 0.01\, \rm R_{\odot}$, and an age of $2.07^{+0.36}_{-0.27}$ Gyr. Put together with the additional transits identified for two of the three outer planets, we constrain the orbital periods of the outer planets and provide updated estimates for the stellar reflex velocities induced by the planets.