A Multi-Period Oscillation in a Stellar Superflare

TL;DR

This study reports a rare multi-periodic quasi-periodic pulsation in a stellar superflare observed by Kepler, indicating that similar magnetohydrodynamic processes may drive both solar and stellar flares.

Contribution

It presents the first detection of multiple independent periodicities in a stellar superflare, suggesting common physical mechanisms with solar flares.

Findings

Detected two significant periodicities of 78 and 32 minutes.

The periodicities are likely independent and related to MHD modes.

Supports the idea that stellar and solar flares share similar physical processes.

Abstract

Flares that are orders of magnitude larger than the most energetic solar flares are routinely observed on Sun-like stars, raising the question of whether the same physical processes are responsible for both solar and stellar flares. In this letter we present a white-light stellar superflare on the star KIC9655129, observed by NASA's Kepler mission, with a rare multi-period quasi-periodic pulsation (QPP) pattern. Two significant periodic processes were detected using the wavelet and autocorrelation techniques, with periods of 78 +/- 12 min and 32 +/- 2 min. By comparing the phases and decay times of the two periodicities, the QPP signal was found to most likely be linear, suggesting that the two periodicities are independent, possibly corresponding either to different magnetohydrodynamic modes of the flaring region, or different spatial harmonics of the same mode. The presence of multiple periodicities is a good indication that the QPPs were caused by magnetohydrodynamic oscillations, and suggests that the physical processes in operation during stellar flares could be the same as those in solar flares.