The TESS View of LOFAR Radio-Emitting Stars

TL;DR

This study uses TESS data to analyze M dwarfs detected by LOFAR, providing evidence that supports the interpretation of radio emissions as star-planet magnetic interactions rather than stellar activity.

Contribution

It offers the first combined analysis of TESS and LOFAR data to distinguish between stellar activity and star-planet interactions in radio-emitting M dwarfs.

Findings

GJ 1151 and three other candidates show low stellar activity.

Most LOFAR-detected M dwarfs exhibit frequent flares.

Stellar activity is unlikely to cause the observed radio emissions.

Abstract

The recent detection of the M dwarf GJ 1151 at 144 MHz low radio frequencies using LOFAR has been interpreted as evidence of an exoplanet magnetically interacting with its host star. This would be the first exoplanet detected around a main sequence star by a radio telescope. Radial velocity confirmation of such a planet has proven inconclusive, and it remains possible that the radio emission could be generated by a stellar coronal process. Using data from TESS, we shed light on this question by probing the stellar activity and flares of GJ 1151 as well as fourteen other M dwarfs detected by LOFAR. GJ 1151 and three other star-planet interaction candidates are found to be inactive, with no rotational modulation and few, if any, flares. The remainder of the LOFAR detected M dwarfs flare frequently. We consider it unlikely that stellar activity is responsible for the bright, circularly-polarized emission from GJ 1151 and its three analogs, and support the star-planet magnetic interaction interpretation.