Flares of M-stars in Upper Scorpius region and flares and CMEs of the active M-star AD Leo

TL;DR

This study analyzes flare activity in young K- and M-stars in Upper Scorpius using Kepler K2 data, revealing significantly higher super-flare frequencies compared to the Sun, and examines flares and CMEs in the active M-star AD Leo.

Contribution

It provides new quantitative measurements of flare frequencies and energy distributions in young stars and reports the absence of CMEs in AD Leo despite frequent flares.

Findings

Young K- and M-stars have 10,000 to 80,000 times more super-flares than the Sun.

Flare energy distribution follows a power-law similar to the Sun's.

No CMEs were detected from AD Leo during the observation period.

Abstract

Using the Kepler K2 data, we studied the flare-activity of young K-and M-stars in the Upper Sco region and found that they have 10000 to 80000 times as many super-flares with E> 5E34 erg than solar like stars. The power-law index for flares is $N/dE~E^-1.2 for K stars, N/dE~E^-1.4 for early M-star and dN/dE~E^-1.3 for late M stars, which is about the same as that of the Sun. We also observed the active M-star AD Leo spectroscopy for 222 hours, detected 22 flares but no coronal mass ejections.