Related papers: The effect of activity on stellar temperatures and…
Observations of low-mass stars have frequently shown a disagreement between observed stellar radii and radii predicted by theoretical stellar structure models. This ``radius inflation'' problem could have an impact on both stellar and…
The fundamental properties of low-mass stars are not as well understood as those of their more massive counterparts. The best method for constraining these properties, especially masses and radii, is to study eclipsing binary systems, but…
We study the time variations of the cycles of 20 active stars based on decades-long photometric or spectroscopic observations. A method of time-frequency analysis, as discussed in a companion paper, is applied to the data. Fifteen stars…
One of the most efficient and reliable observational technique allowing to probe the internal structure of a star is the determination of the apsidal motion in close eccentric binaries. This secular precession of the binary orbit's major…
We present theoretical models of rotating low mass stars (0.1 - 1.0 \Msun) to demonstrate the effect of rotation on the effective temperature and luminosity of stars. The range of rotation rates in our models corresponds to the observed…
We report the discovery of a double-lined, spectroscopic, eclipsing binary in the Orion star-forming region. We analyze the system spectroscopically and photometrically to empirically determine precise, distance-independent masses, radii,…
M dwarf stars comprise 70-80% of the galaxy's stars and host most of its rocky planets. They also importantly differ from Sunlike stars in that they are "active" for billions of years or more: rotating quickly, flaring often, and emitting…
The eclipsing binary LL Aqr is a bright V = 9.32, detached system consisting of two solar-type stars in an eccentric orbit (P = 20.2 d). The secondary component, LL Aqr B, was previously found to have physical and atmospheric parameters…
The architecture of many exoplanetary systems is different from the solar system, with exoplanets being in close orbits around their host stars and having orbital periods of only a few days. We can expect interactions between the star and…
Using recently established empirical calibrations for the impact of chromospheric activity on the radii, effective temperatures, and estimated masses of active low-mass stars and brown dwarfs, we reassess the shape of the initial mass…
We present models designed to quantify the effects of stellar activity on exoplanet transit spectroscopy and atmospheric characterization at low (R = 100) and high (R = 100,000) spectral resolution. We study three model classes mirroring…
We use photometric observations of solar-type stars, made by the NASA Kepler Mission, to conduct a statistical study of the impact of stellar surface activity on the detectability of solar-like oscillations. We find that the number of stars…
We probed stellar X-ray activity over a wide range of stellar parameters, using {\it Chandra} and LAMOST data. We measured the X-ray-to-bolometric luminosity ratio ($R_X = L_X/L_{\rm bol}$) for 484 main-sequence stars, and found a bimodal…
A novel way of looking at the evolution of star clusters is presented. With a dynamical temperature, given by the mean kinetic energy of the cluster stars, and a dynamical luminosity, which is defined as the kinetic energy of the stars…
Long-term observational data have information on the magnetic cycles of active stars and that of the Sun. The changes in the activity of our central star have basic effects on Earth, like variations in the global climate. Therefore…
Stars interact with their planets through gravitation, radiation, and magnetic fields. Although magnetic activity decreases with time, reducing associated high-energy (e.g., coronal XUV emission, flares), stellar winds persist throughout…
Core overshoot is a large source of uncertainty in constructing stellar models. Whether the amount of overshoot is constant or mass dependent is not completely known, even though models sometimes assume a mass-based trend. In this work we…
The apparent size of stars is a crucial benchmark for fundamental stellar properties such as effective temperatures, radii and surface gravities. While interferometric measurements of stellar angular diameters are the most direct method to…
Observations of the coronae of the Sun and of solar-like stars provide complementary information to advance our understanding of stellar magnetic activity, and of the processes leading to the heating of their outer atmospheres. While solar…
Context. In tight binary star systems, tidal interactions can significantly influence the rotational and orbital evolution of both stars, and therefore their activity evolution. This can have strong effects on the atmospheric evolution of…