University of Hertfordshire

From the same journal

From the same journal

By the same authors


  • Meredith A. MacGregor
  • Alycia J. Weinberger
  • R. O. Parke Loyd
  • Evgenya Shkolnik
  • Thomas Barclay
  • Ward S. Howard
  • Andrew Zic
  • Rachel A. Osten
  • Steven R. Cranmer
  • Adam F. Kowalski
  • Emil Lenc
  • Allison Youngblood
  • Anna Estes
  • David J. Wilner
  • Jan Forbrich
  • Anna Hughes
  • Nicholas M. Law
  • Tara Murphy
  • Aaron Boley
  • Jaymie Matthews
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Original languageEnglish
Article numberL25
Number of pages9
JournalAstrophysical Journal Letters
Publication statusPublished - 21 Apr 2021


We present the discovery of an extreme flaring event from Proxima Cen 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 that occurred on 2019 May 1. In the millimeter and FUV, this flare is the brightest ever detected, brightening by a factor of >1000 and >14,000 as seen by ALMA and HST, respectively. The millimeter and FUV continuum emission trace each other closely during the flare, suggesting that millimeter emission could serve as a proxy for FUV emission from stellar flares and become a powerful new tool to constrain the high-energy radiation environment of exoplanets. Surprisingly, optical emission associated with the event peaks at a much lower level with a time delay. The initial burst has an extremely short duration, lasting for <10 s. Taken together with the growing sample of millimeter M dwarf flares, this event suggests that millimeter emission is actually common during stellar flares and often originates from short burst-like events.


© 2021. The American Astronomical Society. All rights reserved. This is the accepted manuscript version of an article which has been published in final form at

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