Flare stars in nearby Galactic open clusters based on TESS data

Abstract

The study is devoted to search for flare stars among confirmed members of Galactic open clusters using high-cadence photometry from TESS mission. We analyzed 957 high-cadence light curves of members from 136 open clusters. As a result, 56 flare stars were found, among them 8 hot B-A type objects. Of all flares, 63 % were detected in sample of cool stars (T eff < 5000 K), and 29 % -in stars of spectral type G, while 23 % in K-type stars and approximately 34% of all detected flares are in M-type stars. Using the FLATW'RM (FLAre deTection With Ransac Method) flare finding algorithm, we estimated parameters of flares and rotation period of detected flare stars. The flare with the largest amplitude appears on the M3 type EQ Cha star. Statistical analysis did not reveal any direct correlation between ages, rotation periods and flaring activity.

Revealing the Binarity of HD 36030—One of the Hottest Flare Stars

“…We did not apply any additional detrending or pre-processing to the data, and the resulting light curves are shown in Figure 7. The light curve from Sector 6 shows a strong flare that has already been reported by Maryeva et al [11] and Balona [18]. Visual inspection of Sector 32 also revealed a flare of smaller amplitude but similar duration.…”

“…We performed a dedicated study of HD 36030, which was the hottest flare star detected by Maryeva et al [11]. We found one more flare in the TESS data that confirmed the repeating nature of the flaring.…”

“…Less frequently, B-type stars show variability related to extended atmospheres and outflows, usually observed in peculiar B-type stars, such as B[e] [7,8] or luminous blue variables (LBVs) [9,10]. Quite unexpectedly, some B stars have also been shown to manifest very energetic stellar flares (e.g., [11] and references therein)-unpredictable dramatic increases in brightness for a few dozen minutes.…”

The GATE summer school

“…Overall, the students, tutors and lecturers did a great job. The results of the students projects are summarized in (Gajdoš et al, 2021;Maryeva et al, 2021;Korth et al, 2021;Merc et al, 2021, this proceedings).…”

“…The binary group tested the robustness and accuracy of parameters using the soon to be released PHOEBE 2.3 EB modeling package (Conroy et al, 2020) on the TESS data of AI Phe (Korth et al, 2021). Project on stellar flares was focused on search for flare stars in 136 open clusters by using TESS light curves and utilizing GAIA data (Maryeva et al, 2021). Finally, the asteroseismic group worked on the global asteroseismic analysis of a heart-beat star KIC 5006817 based on the full Kepler data sample and TESS data (Merc et al, 2021).…”