Related papers: KIC011764567: An evolved object showing substantia…
Context. The Sun and solar-like stars undergo activity cycles for which the underlying mechanisms are not well understood. The oscillations of the Sun are known to vary with its activity cycle and these changes provide diagnostics on the…
The observational mass-radius relation of main sequence stars with masses between ~0.3 and 1.0 Msun reveals deviations between the stellar radii predicted by models and the observed radii of stars in detached binaries. We generate an…
We analyze the photometric short-cadence data obtained with the Kepler Mission during the first eight months of observations of two solar-type stars of spectral types G and F: KIC 11395018 and KIC 11234888 respectively, the latter having a…
In strong stellar and solar flares flare loops typically appear during the decay phase, providing an additional contribution to the flare emission and, possibly, obscuring the flare emission. Super-flares, common in active, cool stars,…
We have used 605 days of photometric data from the Kepler spacecraft to study KIC 6614501, a close binary system with an orbital period of 0.15749747(25) days (3.779939 hours), that consists of a low-mass subdwarf B (sdB) star and a white…
KIC 8560861 (HD 183648) is a marginally eccentric (e=0.05) eclipsing binary with an orbital period of P_orb=31.973d, exhibiting mmag amplitude pulsations on time scales of a few days. We present the results of the complex analysis of high…
Statistically analyzing Johnson UBVR observations of V1285 Aql during the three observing seasons, both activity level and behavior of the star are discussed in respect to obtained results. We also discuss the out-of-flare variation due to…
Flares, energetic eruptions on the surfaces of stars, are an unmistakable manifestation of magnetically driven emission. Their occurrence rates and energy distributions trace stellar characteristics such as mass and age. But before flares…
We analyse light curves covering four years of 39 fast-rotating ($P_\mathrm{rot}< 1d$) late-type active stars from the Kepler database. Using time-frequency analysis (Short-Term Fourier-Transform), we find hints for activity cycles of…
We have performed a non-LTE spectroscopic analysis using far-UV and UV data of the central star of the planetary nebula K1-26 (Longmore 1), and found Teff = 120+/-10 kK, logg = 6.7 +0.3/-0.7, and y = 0.10. The temperature is significantly…
The habitability of planets is closely connected with the stellar activity, mainly the frequency of flares and the distribution of flare energy. Kepler and TESS find many flaring stars are detected via precise time-domain photometric data,…
We present the discovery of nonradial pulsations in five hot subdwarf B (sdB) stars based on 27 days of nearly continuous time-series photometry using the Kepler spacecraft. We find that every sdB star cooler than $\approx 27\,500\,$K that…
Stellar flares are short-duration ($<$ hours) bursts of radiation associated with surface magnetic reconnection events. Stellar magnetic activity generally decreases as a function of both age and Rossby number, $R_0$, a measure of the…
We present a study of flare rates, rotation periods, and spectroscopic activity indicators of 125 single stars within 15 parsecs and with masses between 0.1$-$0.3 $M_\odot$ observed during the first year of the TESS mission, with the goal…
Context. White-light stellar flares are proxies for some of the most energetic types of flares, but their triggering mechanism is still poorly understood. As they are associated with strong X and UV emission, their study is particularly…
Young solar-type stars are known to show frequent "superflares", which may severely influence the habitable worlds on young planets via intense radiations and coronal mass ejections. Here we report an optical spectroscopic and photometric…
KIC 5359678 is a 6.231-d period F-type eclipsing binary system whose component stars both show starspot activity. It was observed by the Kepler satellite in long cadence for the full four-year duration of the mission. Wang et al (2021)…
We present spectroscopic and photometric analysis of KIC\,9451096, where the latter is based on very high precision long cadence photometry obtained by $Kepler$ space craft. Combined spectroscopic and photometric modeling show that the…
Flares are short-lived but energetic manifestations of stellar activity. Studying them is crucial, as they emit intense high-energy radiation that can impact the circumstellar environment, especially the atmospheres of orbiting planets.…
We searched for extrasolar planets around pulsating stars by examining $\textit{Kepler}$ data for transit-like events hidden in the intrinsic variability. All Short Cadence observations for targets with 6000 K $< T_{\rm eff} <$ 8500 K were…