Related papers: Stellar activity as a tracer of moving groups
We conduct a study of K to M type stars to investigate the activity and the rotation limit in the Hyades. We use a sample of 40 stars in this intermediate-age cluster (~625 Myr) to probe stellar rotation in the threshold region where…
We have analysed the kinematics of a sample of 114 hot subdwarf stars, for 2/3 of which we present new proper motions, spectroscopic and photometric data. The vast majority of the stars show a kinematic behaviour that is similar to that of…
The Sun and stars with low magnetic activity levels, become photometrically brighter when their activity increases. Magnetically more active stars display the opposite behaviour and get fainter when their activity increases. We reproduce…
Using a recent census of flare stars from the Kepler survey, we have explored how flare activity evolves across stellar main sequence lifetimes. We utilize a sample of 347 stars with robust flare activity detections, and which have rotation…
The European Space Agency's Gaia space telescope, launched in 2013, aims to measure the positions, parallaxes, and proper motions of a billion stars in our Galaxy and throughout the Local Group. In doing so it will include hundreds of…
Context. Recent studies have suggested that moving groups have a dynamic or "resonant" origin. Under this hypothesis, these kinematic structures become a powerful tool for studying the large-scale structure and dynamics of the Milky Way.…
From the tangential velocities of stars all over the sky, one can, in a statistical way, infer their 3D velocity distribution. An application to Hipparcos data reveals rich structure in the planar stellar motions: there are several moving…
The spatial-kinematic structure of 48 young star clusters and associations is investigated. Moran's $I$ statistic is used to quantify the degree of kinematic substructure in each region, and the results are compared to those expected…
Aims. We are searching for new open clusters or moving groups in the Solar neighbourhood. Methods. We used the Gaia-TGAS catalogue, cut it into narrow proper motion and parallax slices and searched for significant spatial over-densities of…
We conducted a panoramic spectroscopic campaign with MOSCA at the Calar Alto observatory. We acquired spectra of more than 500 objects. Approximately 150 of these spectra were of galaxies that are members of six different clusters, which…
The Kepler mission has been providing high-quality photometric data leading to many breakthroughs in the exoplanet search and in stellar physics. Stellar magnetic activity results from the interaction between rotation, convection, and…
We present a sample of 824 solar and late-type stars with X-ray luminosities and rotation periods. This is used to study the relationship between rotation and stellar activity and derive a new estimate of the convective turnover time. From…
We present a catalogue of rotation and chromospheric activity in a sample of 334 M dwarfs of spectral types M0--M4.5 populating the parameter space around the boundary to full convection. We obtained high-resolution optical spectra for 206…
Debate over the existence of branches in the stellar activity-rotation diagrams continues. Application of modern time series analysis tools to study the mean cycle periods in chromospheric activity index is lacking. We develop such models,…
Interacting galaxies are known to have higher global rates of star formation on average than normal galaxies, relative to their stellar masses. Using UV and IR photometry combined with new and published H-alpha images, we have compared the…
In the search for planets orbiting distant stars the presence of stellar activity in the atmospheres of observed stars can obscure the radial velocity signal used to detect such planets. Furthermore, this stellar activity contamination is…
We perform numerical simulations of a stellar galactic disk with initial conditions chosen to represent an unrelaxed population which might have been left following a merger. Stars are unevenly distributed in radial action angle, though the…
The stellar dynamics of Omega Centauri are inferred from the radial velocities of 469 stars measured with CORAVEL (Mayor et al. 1997). Rather than fit the data to a family of models, we generate estimates of all dynamical functions…
We present the results of radial velocity measurements of two samples of active stars. The first sample contains field G and K giants across the Red Giant Branch, whereas the second sample consists of nearby young stars (d < 150 pc) with…
We have investigated a group of stars known to have low chromospheric ages, but high kinematical ages. Isochrone, chemical and lithium ages are estimated for them. The majority of stars in this group show lithium abundances much smaller…