The solar magnetism is no more considered as a purely superficial phenomenon. The SoHO community has shown that the length of the solar cycle depends on the transition region between radiation and convection. Nevertheless, the internal solar (stellar) magnetism stays poorly known. Starting in 2008, the American instrument HMI/SDO and the European

When the polarimetric sensitivity and the angular resolution exceed a threshold, magnetic fields show up almost everywhere on the solar surface. Here I revise the observational properties of the weakest polarization signals, which appear in the InterNetwork (IN) regions. We already have some information on the magnetic field strengths and

The mass of CoRoT-7b, the first transiting super-Earth exoplanet, is still a subject of debate. A wide range of masses have been reported in the literature ranging from as high as 8 M ⊕ to as low as 2.3 M ⊕. This range in mass is largely due to the activity level of the star that contributes a significant amount of radial velocity (RV) "jitter" and

Context. The “mass discrepancy” in massive O stars represents a long-standing problem in stellar astrophysics with far-reaching implications for the chemical and dynamical feedback in galaxies. Aims: Our goal is to investigate this mass discrepancy by comparing state-of-the-art model masses with model-independent masses determined from eclipsing

We report on the optical spectroscopy of the eclipsing halo low-mass X-ray binary 2S 0921-630, which reveals the absorption-line radial velocity curve of the K0 III secondary star with a semiamplitude K2=92.89+/-3.84 km s-1, a systemic velocity γ=34.9+/-3.3 km s-1, and an orbital period Porb of 9.0035+/-0.0029 days (1 σ). Given the quality of the

Presently every telescope at McDonald Observatory is utilized for the search for extrasolar planets. Here we give an overview of the precision Doppler surveys currently in progress at the 9.2 m Hobby-Eberly Telscope (HET) and the Harlan J. Smith 2.7 m telescope. Other planet search programs at McDonald Observatory include a transit search at the 0