Two planetary systems with transiting Earth-size and super-Earth planets orbiting late-type dwarf stars

TL;DR

This paper reports the discovery of two new planetary systems around cool dwarf stars, each hosting multiple transiting Earth-size and super-Earth planets, with detailed characterization of their orbital and physical properties.

Contribution

The study presents the identification and characterization of two new multi-planet systems around late-type dwarf stars using K2 data, including their orbital configurations and potential atmospheric signals.

Findings

Three Earth-size planets in near-resonance orbit around K2-239

Two super-Earths orbiting K2-240 with distinct periods

Estimated atmospheric temperatures and transmission spectroscopy signals

Abstract

We present two new planetary systems found around cool dwarf stars with data from the K2 mission. The first system was found in K2-239 (EPIC 248545986), char- acterized in this work as M3.0V and observed in the 14th campaign of K2. It consists of three Earth-size transiting planets with radii of 1.1, 1.0 and 1.1 R Earth, showing a compact configuration with orbital periods of 5.24, 7.78 and 10.1 days, close to 2:3:4 resonance. The second was found in K2-240 (EPIC 249801827), characterized in this work as M0.5V and observed in the 15th campaign. It consists of two transiting super-Earths with radii 2.0 and 1.8 R Earth and orbital periods of 6.03 and 20.5 days. The equilibrium temperatures of the atmospheres of these planets are estimated to be in the range of 380-600 K and the amplitudes of signals in transmission spectroscopy are estimated at ~10 ppm.