Statistical Analysis and the OPEA Model of the White-Light Flares Occurring on Kr\"uger 60B (DO Cep)

TL;DR

This study presents extensive statistical analysis of white-light flares on Krüger 60B (DO Cep), classifying flares into fast and slow types, modeling their behaviors, and deriving insights into their energies and loop geometries.

Contribution

It introduces the largest flare dataset for DO Cep, classifies flares into subtypes using statistical tests, and models flare behaviors with exponential functions to understand their physical properties.

Findings

Fast and slow flares are distinguishable with a critical decay/rise time ratio of 3.40.

Fast flares constitute 20.22% of the total, slow flares 79.78%.

Flares show a significant energy difference, with a 39.282-fold variation.

Abstract

In this study, new observations and some results of statistical analyses are presented. The largest flare data set of DO Cep in the literature has been obtained with 89 flares detected in 67.61 hours of U-band flare patrol. First of all, the observations demonstrated that the star is one of the most active flare stars in respect to the computed flare frequency. Secondly, using the independent samples t-test, the detected flares were classified into two subtypes, and then they were modelled. Analysing the models demonstrated that the fast and slow flares occurring on the star can be separated with a critical value of the ratio of their decay time to rise time. The critical value was computed as 3.40. According to this value, the fast flare rate is 20.22%, while the slow flare rate is 79.78%. Besides, there is a 39.282 times difference between the energies of these two types of flares. However, the flare equivalent durations versus the flare rise times increase in similar ways for both groups. In addition, all all the flares were modelled with the one-phase exponential association function. Analysing this model, the plateau value was found to be 2.810. Moreover, the half-life value was computed as 433.1s from the model. The maximum flare rise time was found to be 1164s, while the maximum flare total duration was found to be 3472s. The results of the flare timescales indicate that the geometry of the flaring loop on the surface of the star might be similar to those seen on analogues of DO Cep. Consequently, considering both the half-life value and flare timescales, the flares detected on the surface of DO Cep get maximum energy in longer times, while the geometries of the flaring loops or areas get smaller.