Statistical Analysis and the OPEA Model of the White-Light Flares Occurring on Krüger 60B (DO Cep)
Hasan Ali DalDepartment of Astronomy and Space Sciences, University of Ege, Bornova, 35100 İzmir, Turkey. Email: ali.dal@ege.edu.tr
Publications of the Astronomical Society of Australia 28(4) 365-377 https://doi.org/10.1071/AS11034
Submitted: 3 July 2011 Accepted: 26 September 2011 Published: 7 November 2011
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 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 433.1 s from the model. The maximum flare rise time was found to be 1164 s, while the maximum flare total duration was found to be 3472 s. 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.
Keywords: methods: data analysis — methods: statistical — stars: spots — stars: flare — stars: individual (DO Cep)
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