Discovery of an Extremely Short Duration Flare from Proxima Centauri Using Millimeter through FUV Observations

TL;DR

This paper reports the discovery of an extremely short, intense stellar flare from Proxima Centauri across multiple wavelengths, revealing millimeter emission as a potential proxy for high-energy stellar activity affecting exoplanets.

Contribution

It introduces the first observation of a very short-duration flare from Proxima Centauri with multi-wavelength data, highlighting millimeter emission as a new tool for studying stellar flares.

Findings

The flare was the brightest detected in millimeter and FUV wavelengths.

Millimeter and FUV emissions closely trace each other during the flare.

Optical emission peaks later and at lower levels, indicating different emission mechanisms.

Abstract

We present the discovery of an extreme flaring event from Proxima Cen by ASKAP, ALMA, HST, 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 >14000 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 sec. 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.