Kepler super-flare stars: what are they?

TL;DR

This study investigates the nature of super-flare stars observed by Kepler, using high-resolution spectroscopy to analyze their properties and assess the potential for such extreme flares on Sun-like stars.

Contribution

The paper presents the first high-resolution spectroscopic analysis of super-flare stars, revealing diverse stellar characteristics and challenging simple explanations for super-flare origins.

Findings

Several super-flare stars are very young and fast-rotating with high activity levels.

Some stars show no clear link between age or rotation and super-flare occurrence.

Results suggest multiple mechanisms may produce super flares on solar-type stars.

Abstract

The Kepler mission has led to the serendipitous discovery of a significant number of `super flares' - white light flares with energies between 10^33 erg and 10^36 erg - on solar-type stars. It has been speculated that these could be `freak' events that might happen on the Sun, too. We have started a programme to study the nature of the stars on which these super flares have been observed. Here we present high-resolution spectroscopy of 11 of these stars and discuss our results. We find that several of these stars are very young, fast-rotating stars where high levels of stellar activity can be expected, but for some other stars we do not find a straightforward explanation for the occurrence of super flares.