Radio Burst from a Stellar Coronal Mass Ejection

TL;DR

This paper reports the first detection of a stellar coronal mass ejection signature via a Type II radio burst from an M dwarf, providing new observational insights into stellar CMEs and their potential effects on exoplanets.

Contribution

It presents the first unambiguous detection of a CME from a star outside the Sun using radio burst observations, establishing observational limits on stellar CME rates and impacts.

Findings

Detected a Type II radio burst from an M dwarf star.

Estimated CME occurrence rate of approximately 0.84×10^{-3} per day per star.

Implication that stellar CME properties can now be directly studied rather than extrapolated from solar data.

Abstract

Coronal mass ejections (CMEs) are massive expulsions of magnetised plasma from a star, and are the largest contributors to space weather in the Solar System. CMEs are theorized to play a key role in planetary atmospheric erosion, especially for planets that are close to their host star. However, such a conclusion remains controversial as there has not been an unambiguous detection of a CME from a star outside of our Sun. Previous stellar CME studies have only inferred the presence of a CME through the detection of other types of stellar eruptive events. A signature of a fast CME is a Type II radio burst, which is emitted from the shock wave produced as the CME travels through the stellar corona into interplanetary space. Here we report an analogue to a Type II burst from the early M dwarf StKM 1-1262. The burst exhibits identical frequency, time, and polarisation properties to fundamental plasma emission from a solar Type II burst. We demonstrate the rate of such events with similar radio luminosity from M dwarfs are 0.84$^{+1.94}_{-0.69} \times$10$^{-3}$ per day per star. Our detection implies that we are no longer restricted to extrapolating the solar CME kinematics and rates to other stars, allowing us to establish the first observational limits on the impact of CMEs on exoplanets.