New cases of super-flares on slowly rotating solar-type stars and large amplitude super-flares in G- and M-type main-sequence stars

Abstract

In our previous work, we searched for super-flares on different types of stars while focusing on G-type dwarfs using entire Kepler data to study statistical properties of the occurrence rate of super-flares. Using these new data, as a by-product, we found fourteen cases of super-flare detection on thirteen slowly rotating Sun-like stars with rotation periods of 24.5 to 44 days. This result supports earlier conclusion by others that the Sun may possibly have a surprise super-flare. Moreover, we found twelve and seven new cases of detection of exceptionally large amplitude super-flares on six and four main-sequence stars of G- and M-type, respectively. No large-amplitude flares were detected in A, F, or K main-sequence stars. Here we present preliminary analysis of these cases. The super-flare detection, i.e. an estimation of flare energy, is based on a more accurate method compared to previous studies. We fit an exponential decay function to flare light curves and study the relation between e-folding decay time, $\tau$, vs. flare amplitude and flare energy. We find that for slowly rotating Sun-like stars, large values of $\tau$ correspond to small flare energies and small values of $\tau$ correspond to high flare energies considered. Similarly, $\tau$ is large for small flare amplitudes and $\tau$ is small for large amplitudes considered. However, there is no clear relation between these parameters for large amplitude super-flares in the main sequence G- and M-type stars, as we could not establish clear functional dependence between the parameters via standard fitting algorithms.

The final version is accepted for publication in Research in Astronomy and Astrophysics (2023)

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Cited by in corpus (2)

• Spectroscopic observations of flares and superflares on AU Mic
• Prediction of short stellar activity cycles using derived and established empirical relations between activity and rotation periods