X-ray Emission from the Exoplanet Hosting LTT 1445 Triple Star System

TL;DR

This study used Chandra X-ray observations to resolve and analyze the X-ray emission of the LTT 1445 triple star system, providing data crucial for understanding the atmospheres of its orbiting rocky planets.

Contribution

First spatially resolved and measured X-ray luminosities of all three stars in the LTT 1445 system, including the host star of nearby rocky planets.

Findings

Detected all three stars in X-ray; measured their luminosities.

Observed strong X-ray flux variability in two stars.

Analyzed coronal properties at different activity levels.

Abstract

JWST will be able to observe the atmospheres of rocky planets transiting nearby M dwarfs. The M dwarf triple star system LTT 1445, at a distance of 6.86 pc, hosts some of the nearest rocky terrestrial planets. These planets most likely orbit the M 3.5V star LTT 1445A. During a 28.6 ksec Chandra ACIS-S3 observation we have i) spatially resolved and detected all three stars in the LTT 1445 system, ii) measured the X-ray luminosity of the individual stars, including LTT 1445A, for the first time, iii) studied the flux variability of the X-ray sources and found strong variability from the A and C components, and iv) investigated how the coronal luminosities, temperatures and volume emission measures vary at different activity levels. Combining these X-ray data with upcoming HST ultraviolet observations will allow a differential emission measure (DEM) estimation of the star's EUV spectrum, thereby facilitating modeling of the rocky planets' atmospheres.