Significant High-Energy Flares Detected in M Dwarf Stars LTT 1445A and GJ 486

Recent observations of the stars LTT 1445A and GJ 486 have revealed significant high-energy activity, including flares that could impact our understanding of exoplanet atmospheres. The study, titled "High-energy spectra of LTT 1445A and GJ 486 reveal flares and activity," was conducted by H. Diamond-Lowe and 21 co-authors and published on arXiv (arXiv:2407.00165).

The research utilized data from various telescopes, including XMM-Newton, Chandra, and Hubble Space Telescope (HST), to analyze the high-energy spectra of these M dwarf stars. Notably, GJ 486 exhibited two flares with absolute energies of approximately 10^29.5 and 10^30.1 erg, occurring three hours apart. These flares had durations of about 4357 seconds and 19724 seconds, respectively. The authors suggest that these flares are indicative of heightened flaring activity that may persist for several days.

The findings indicate that while LTT 1445A and GJ 486 appear inactive at optical wavelengths, they exhibit significant activity in the ultraviolet and X-ray ranges. This discrepancy highlights the importance of consistent high-energy monitoring to better understand the duration and extent of such activity on M dwarfs and their potential effects on surrounding exoplanets.

The study also calculated that the planets orbiting these stars could retain CO2 atmospheres under certain conditions, which is crucial for assessing their habitability. The ages of the host stars were estimated to be at least 2.2 and 6.6 billion years, respectively.

These insights contribute to the broader understanding of how stellar activity influences planetary atmospheres, particularly for the closest terrestrial exoplanets transiting M dwarfs.

For further details, the full paper can be accessed at arXiv:2407.00165.