Related papers: Chromospheric activity in bright contact binary st…

Based on Kepler data, we present the results of a search for white-light flares on 1049 close binaries. We identify 234 flare binaries, on which 6818 flares are detected. We compare the flare-binary fraction in different binary morphologies…

We report intensive monitoring of the activity variability in the H$\alpha$ line for 10 Sun-like stars using the 1.88-m reflector at Okayama Branch Office, Subaru Telescope, during the last four years 2019-2022. Our aim was to investigate…

Kinematics of 237 Chromospherically Active Binaries (CAB) were studied. The sample is heterogeneous with different orbits and physically different components from F to M spectral type main sequence stars to G and K giants and super giants.…

The atmospheric activity of the Sun and solar-type stars is analysed involving observations from HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Observatories, and the…

M-type stars are crucial for stellar activity studies since they cover two types of magnetic dynamos and particularly intriguing for habitability studies due to their abundance and long lifespans during the main-sequence stage. In this…

We present empirical relations for determining the amount by which the effective temperatures and radii---and therefore the estimated masses---of low-mass stars and brown dwarfs are altered due to chromospheric activity. Accurate estimates…

Do extrasolar planets affect the activity of their host stars? Indications for chromospheric activity enhancement have been found for a handful of targets, but in the X-ray regime, conclusive observational evidence is still missing. We want…

We combine the catalogue of eclipsing binaries from the All Sky Automated Survey (ASAS) with the ROSAT All Sky Survey (RASS). The combination results in 836 eclipsing binaries that display coronal activity and is the largest sample of…

To detect stellar activity cycles and study the possible star-planet interactions (SPI's), we have developed both HK$\alpha$ and SPI-HK$\alpha$ projects since 1999 and 2012 respectively. In this work, we present preliminary results of…

Chromospheric activity is widely used as an age indicator for solar-type stars based on the early evidence that there is a smooth evolution from young and active to old and inactive stars. We analysed chromospheric activity in five…

Overcontact binary stars are systems of two stars where the component stars are in contact with each other. This implies that they share a common envelope of gas. In this work we seek signatures of nonlinearity and chaos in these stars by…

Previous studies have found that red giants (RGs) in close binary systems undergoing spin-orbit resonance exhibit an enhanced level of magnetic activity with respect to single RGs rotating at the same rate, from measurements of photometric…

We show that candidate contact binary asteroids can be efficiently identified from sparsely sampled photometry taken at phase angles >60deg. At high phase angle, close/contact binary systems produce distinctive lightcurves that spend most…

We present results from a high-resolution spectroscopic survey of 45 L dwarfs, which includes both very low-mass stars and brown dwarfs. Our spectra allow us to derive a significant number of new rotational velocities, and discover a slowly…

We investigate the fast-rotating (P_orb=P_rot=0.465d), active dwarf binary V405 And (M0V+M5V) using photometric BV(RI)_C and optical spectroscopic data. The light variation is caused by the combined effect of spottedness and binarity with a…

In this study, we consider chromospheric heating models for 55 Cancri in conjunction with observations. The theoretical models, previously discussed in Paper I, are self-consistent, nonlinear and time-dependent ab-initio computations…

We determine rotation periods of a sample of 48 late F-type to mid-M dwarf stars using time-series high-resolution spectroscopy of the Ca II H&K and H-alpha chromospheric activity indicators. We find good agreement between the rotation…

The complexity of composite spectra of close binary star system makes study of the spectra of their component stars extremely difficult. For this reason there exists very little information on the photospheric chemical composition of stars…

For more than half a century, the puzzling W-type phenomenon in contact binaries has challenged astrophysicists. In these systems, the less massive component exhibits a higher surface temperature than its more massive companion, which is a…

We present five decades of chromospheric activity measurements in 59 Sun-like stars as time series. These include and extend the 35 yr of stellar chromospheric activity observations by the Mount Wilson Survey (1966--2001), and continued…