High-level magnetic activity nature of the eclipsing binary KIC 12418816

Abstract

We present comprehensive spectroscopic and photometric analysis of the detached eclipsing binary KIC 12418816, which is composed of two very similar and young main sequence stars of spectral type K0 on a circular orbit. Combining spectroscopic and photometric modelling, we find masses and radii of the components as 0.88±0.06 M ⊙ and 0.84±0.05 M ⊙ , and 0.85±0.02 R ⊙ , and 0.84±0.02 R ⊙ for the primary and the secondary, respectively. Both components exhibit narrow emission features superposed on the cores of the Ca ii H&K lines, while H α and H β photospheric absoprtion is more completely infilled by broader emission. Very high precision Kepler photometry reveals remarkable sinusoidal light variation at out-of-eclipse phases, indicating strong spot activity, presumably on the surface of the secondary component. Spots on the secondary component appear to migrate towards decreasing orbital phases with a migration period of 0.72±0.05 year. Besides the sinusoidal variation, we detect 81 flares, and find that both components possess flare activity. Our analysis shows that 25 flares among 81 come exhibit very high energies with lower frequency, while the rest of them are very frequent with lower energies.

A Pulsating Flare Star in the New Planetary System: Koi-258

“…In order to reveal where KOI-258 is located among similar targets regarding flare activity, we derived the cumulative flare frequency distribution depending on the flare equivalent duration instead of the flare energy. In the literature, a similar model was derived recently for KIC 12418816 (one of the most interesting systems) by Dal &Özdarcan (2018). If their flare cumulative frequency distributions are compared, it will be seen that the interval of flare cumulative frequencies is spread from log(ν) of −1.50 h −1 to 0.00 h −1 for Group 1 and from −1.50 h −1 to +0.30 h −1 for Group 2 in the case of KIC 12418816, while it is spread from log(ν) of −3.1 h −1 to −1.3 h −1 for KOI-258.…”

“…UV Ceti type flare stars exhibit a random flare distribution in time. However, recent studies such as Yoldaş & Dal (2017b), Dal &Özdarcan (2018 and Yoldaş & Dal (2019), indicate that flares tend to aggregate around certain phases. The flare number distribution shown in Figure 13 indicates two important cases, which indicates that KOI-258's flares occur in each phase, and occur randomly as well, as do those on UV Ceti type single stars.…”

Determination of X-ray Flare Behavior in Solar Activity with OPEA Model

“…Literatüre baktığımızda, Kepler verileri kullanılarak yapılan çalışmalarda bazı örten çift sistemlerin sergilediği flare aktivitesi için oluşturulan OPEA modellerinin birden fazla model gerektirdiği görülmüştür (Kamil & Dal 2017;Dal & Özdarcan 2018;Yoldaş & Dal 2021). Ancak birden fazla model gerektirecek flare gruplarının kaynağı hakkında tartışmalar hala belirsizliğini korumaktadır.…”

Magnetic activity and orbital parameters of CC Com based on photometric data, LAMOST low- and medium-resolution spectra

“…Pi et al (2019) obtained starspot activity cycles of DV Psc based on approximately 10 years of photometric observations. In long-term photometric monitoring programs, astronomers have detected many flare events of active binaries and determined their corresponding flare parameters (amplitude, duration, etc) (Qian et al 2012;Luo et al 2019;Pi et al 2019;Dal & Özdarcan 2018). Cao et al (2019) determined chromospheric activity indicators, and detected plage, flare event and prominence.…”