A system of three transiting super-Earths in a cool dwarf star

TL;DR

This paper reports the discovery of three transiting super-Earths around a cool K dwarf star, providing valuable data for understanding super-Earth formation, composition, and habitability potential.

Contribution

First detection of a three-planet super-Earth system around a cool dwarf star using K2 data and detailed stellar characterization.

Findings

Planets have radii of 1.8, 2.6, and 1.9 Earth radii.

Orbital periods are 6.34, 13.85, and 40.72 days.

The outer planet is near the habitable zone.

Abstract

We present the detection of three super-Earths transiting the cool star LP415-17, monitored by K2 mission in its 13th campaign. High resolution spectra obtained with HARPS-N/TNG showed that the star is a mid-late K dwarf. Using spectral synthesis models we infer its effective temperature, surface gravity and metallicity and subse- quently determined from evolutionary models a stellar radius of 0.58 R Sun. The planets have radii of 1.8, 2.6 and 1.9 R Earth and orbital periods of 6.34, 13.85 and 40.72 days. High resolution images discard any significant contamination by an intervening star in the line of sight. The orbit of the furthest planet has radius of 0.18 AU, close to the inner edge of the habitable zone. The system is suitable to improve our understanding of formation and dynamical evolution of super-Earth systems in the rocky - gaseous threshold, their atmospheres, internal structure, composition and interactions with host stars.