Proxima Centauri, the closest star to our Sun, hosts an Earth-like planet called Proxima Cen b. This planet might be able to harbor life, however, this critically depends on its illumination with high-energy radiation from Proxima Cen's active chromosphere and corona. These UV and X-ray photons are efficiently absorbed in the planetary atmosphere so that they critically affect the planetary climate as well as the planet's water content on the long term.

To investigate the habitability of the planet Proxima Cen b, scientists from the Hamburger Sternwarte in collaboration with their colleagues from the US, India, Chile, France, and several institutes within Germany coordinated a sophisticated multi-wavelength campaign. Several of the most advanced astronomical facilities joined forces to probe the high-energy environment of our nearest exoplanetary neighbor. In particular, three satellite observatories, the Hubble Space Telescope, the Chandra X-ray observatory, and India's ASTROSAT simultaneously observed Proxima Cen together with ground-based facilities like ESO HARPS.

Proxima Centauri is a known flare star and several large flares, i.e., explosion-like events that release large amounts of energy, occurred during the observations. One particularly strong flare (shown in the Figure) was observed by all participating telescopes and caused an average flux increase by a factor of about ten at X-ray as well as FUV wavelengths. The scientists are now investigating the characteristics of these flaring events to understand the implications for potential life on Proxima Cen b.


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