High-Level Magnetic Activity on a Low-Mass Close Binary: GSC 02038-0293

Abstract

Taking into account results obtained from light-curve analysis and out-of-eclipse analyses, we discuss the nature of GSC 02038-00293 and also its magnetic activity behaviour. We obtained light curves of the system during observing seasons 2007, 2008 and 2011. We obtained its secondary minimum clearly in I-band observations in 2008 for the first time. Analysing this light curve, we found the physical parameters of the components. The light-curve analysis indicates that the possible mass ratio of the system is 0.35. We obtained the remaining V-band light curves, extracting the eclipses. We modelled these remaining curves using the SPOTMODEL program and found possible spot configurations of the magnetically active component for each observing season. The models demonstrated that there are two active longitudes for the active component. The models reveal that both active longitudes migrate in the direction of decreasing longitude. We also examined the light curves in out-of-eclipse phases with respect to minimum and maximum brightness, amplitude, etc. The amplitude of the curves during out-of-eclipse phases varies in a sinusoidal way with a period of ,8.9 yr; the mean brightness of the system is dramatically decreasing. The phases of the deeper minimum during out-of-eclipse periods exhibit a migration toward decreasing phase.

KIC 2557430: A Triple System Containing One γ Dor and Two Flaring Components?

“…Thus, the flares of Group 2 should come from the primary component. However, it is not possible due to its ( B − V ) colour index according to the results obtained by Dal & Evren (2011) and Dal et al (2012). At this point, our thought is that the flares of Group 2 could come from the third body the light curve analysis indicated.…”

“…Considering the errors of the Plateau values, it is clearly seen that these Plateau values cannot be equal to each other, which is very interesting because there is not any other sample for this case. According to the results obtained by Dal & Evren (2011) and Dal, Sipahi, & Özdarcan (2012), the flares detected from one star are always modelled with just one OPEA model. However, the flares detected from KIC 2557430 must be modelled with two different OPEA models.…”

“…However, the flares detected from KIC 2557430 must be modelled with two different OPEA models. Dal & Evren (2011) and Dal et al (2012) demonstrated that the OPEA models were formed depending on the stellar ( B − V ) colour indexes. Thus, two OPEA models derived for the flares detected from KIC 2557430 definitely indicate existence of two flare sources in this system.…”

Detailed Chromospheric Activity Nature of KIC 9641031

“…For example, the amplitude variations of the sinusoidal variation are lower than a few mmag, while it is clearly seen that this amplitude and light curve shapes are changing from one cycle to the next in short time intervals. However, in the case of observations made by the ground-based telescopes, the variations of both the amplitude and the shape of the light curve due to the sinusoidal variations caused by rotational modulation can be perceived in a few months at least or generally from one season to the next (Dal, Sipahi, & Özdarcan 2012).…”

“…In addition, although both the minimum location and the shape of sinusoidal light variations due to the rotational modulation out-of-eclipses seem to be rapidly changing, but the amplitude of the variations is not large as much as that observed from other systems (Dal et al 2012). Nonetheless, KIC 9641031 has one chromospherically active component at least.…”