Related papers: A correlation between host star activity and plane…
Contact binary stars are common variable stars which are all believed to emit relatively large fluxes of x-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope with x-ray data from the…
We have assembled a sample of $\sim$8200 stars with spectral types F5V-M5V, all having directly measured X-ray luminosities from eROSITA and rotation periods from TESS, and having empirically estimated ages via their membership in stellar…
We consider the effects of mutual transits by extrasolar planet-companion systems (in a true binary or a planet-satellite system) on light curves. We show that induced changes in light curves depend strongly on a ratio between a…
Stars interact with their close-in planets through radiation, gravitation, and magnetic fields. We investigate the energy input to a planetary atmosphere by reconnection between stellar and planetary magnetic fields and compare it to the…
The purpose of this work is to supplement the "Stars with solar-type activity" catalog with information about confirmed exoplanets and exoplanet candidates. To do this, cross-identification of the catalog stars with data from the NASA…
The chromospheric activity index logR'HK of stars hosting transiting hot Jupiters appears to be correlated with the planets' surface gravity. One of the possible explanations is based on the presence of condensations of planetary evaporated…
Why bother with asteroseismology while studying exoplanets? There are several answers to this question. Asteroseismology and exoplanetary sciences have much in common and the synergy between the two opens up new aspects in both fields.…
The radial velocity method for detecting extra-solar planets relies on measuring the star's wobble around the system's center of mass. Since this is an indirect method, we may ask if there are other dynamical effects that can mimic such…
Both stars and planets can lose mass through an expansive wind outflow, often constrained or channeled by magnetic fields that form a surrounding magnetosphere. The very strong winds of massive stars are understood to be driven by…
The interaction between the magnetic fields of late-type stars and their close-by planets may produce stellar flares as observed in active binary systems. However, in spite of several claims, conclusive evidence is still lacking. We…
Planets with non-zero obliquity and/or orbital eccentricity experience seasonal variations of stellar irradiation at local latitudes. The extent of the atmospheric response can be crudely estimated by the ratio between the orbital timescale…
X-ray emission is an important tracer of stellar magnetic activity. We carried out a systematic correlation analysis for the X-ray luminosity $\log L_{\rm X}$, bolometric luminosity $\log L_{\rm bol}$, and X-ray activity level…
Planets in close orbits around their host stars are subject to strong irradiation. High-energy irradiation, originating from the stellar corona and chromosphere, is mainly responsible for the evaporation of exoplanetary atmospheres. We have…
Studies of element abundances in stars are of fundamental interest for their impact in a wide astrophysical context, from our understanding of galactic chemistry and its evolution, to their effect on models of stellar interiors, to the…
A significant population of stars with ages younger than the Pleiades exists in the solar neighborhood. They are grouped in loose young associations, sharing similar kinematical and physical properties, but, due to their vicinity to the…
Since the first discovery of an extrasolar planetary system more than a decade ago, hundreds more have been discovered. Surprisingly, many of these systems harbor Jupiter-class gas giants located close to the central star, at distances of…
Most known extrasolar planets (exoplanets) have been discovered using the radial velocity$^{\bf 1,2}$ or transit$^{\bf 3}$ methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that…
Precise exoplanet characterization requires precise classification of exoplanet host stars. The masses of host stars are commonly estimated by comparing their spectra to those predicted by stellar evolution models. However,…
Context: According to theory, high-energy emission from the coronae of cool stars can severely erode the atmospheres of orbiting planets. No observational tests of the long term effects of erosion have yet been made. Aims: To analyze the…
We present a population study of 20 exoplanets, ranging from Neptune-like to inflated hot-Jupiter planets, observed during transit with the STIS and WFC3 instruments aboard the Hubble Space Telescope. To obtain spectral information from the…