2022AJ....164..206B

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 ks 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 estimation of the star's extreme-ultraviolet spectrum, thereby facilitating modeling of the rocky planets' atmospheres.