Free Astronomy Magazine July-August 2021

36 JULY-AUGUST 2021 ASTRO PUBLISHING magnetic spectrum, from radio waves to gamma rays. This is the first time that a single stellar flare, other than those that occur on the Sun, has been observed with such com- plete wavelength coverage. The study was precipitated by the serendipitous discovery of a flare from Proxima Centauri in 2018 ALMA archival data. “We had never seen an M dwarf flare at millimeter wavelengths before 2018, so it was not known whether there was cor- responding emission at other wave- lengths,” said Meredith MacGregor, an assistant professor at the Center for Astrophysics and Space Astron- omy (CASA) and Department of As- trophysical and Planetary Sciences (APS) at CU Boulder, and the lead author on the study. To better un- derstand the flares on Proxima Cen- tauri — a red dwarf star located roughly four light-years or 20 trillion miles from Earth — a team of as- tronomers observed the star for 40 hours over the course of several months in 2019 using nine telescopes on the ground and in space. In May 2019, Proxima Centauri ejected a violent flare that lasted just seven seconds, but generated a surge in both ultraviolet and mil- limeter wavelengths. The flare was characterized by a strong, impulsive spike never before seen at these Stellar flare from Proxima Centauri recorded in multiple wavelengths by ALMA Observatory A stronomers using the Ata- cama Large Millimeter/sub- millimeter Array (ALMA) have spotted a flare from Earth’s nearest neighboring star, Proxima Centauri, that is 100 times more powerful than any similar flare seen from the Sun. The flare, which is the largest ever recorded from the star, has revealed the inner workings of such events to astronomers, and could help to shape the hunt for life beyond the Solar System. Stellar flares occur when the release of magnetic energy in stellar spots explodes in an intense burst of elec- tromagnetic radiation that can be observed across the entire electro-