MacGregor et al. have reported the discovery of an extreme flaring event from the star Proxima Centauri by the Australian Square Kilometre Array Pathfinder (ASKAP), Atacama Large Millimeter/submillimeter Array (ALMA), Hubble Space Telescope (HST), Transiting Exoplanet Survey Satellite (TESS), and the du Pont Telescope. In the millimeter and far-ultraviolet bands, this flare is the brightest ever detected, brightening by a factor of >1000 and >14,000 as seen by ALMA and HST, respectively.

The ASKAP observations show faint, ∼ 50% circularly-polarized emission throughout the entire 14-hour observation, including a slowly-declining flux component that is not seen on any other day of the campaign. But no radio burst counterpart was detected by ASKAP. This apparent lack of correlation between low-frequency (< 1 GHz) and higher frequency activity is commonly observed from active M-dwarf stars, and may indicate that the physical driver for low-frequency activity is independent of the processes driving flaring activity observed in higher-frequency wavebands The results of the study were reported this week in The Astrophysical Journal Letters. (Image credit: S. Dagnello, NRAO/AUI/NSF)