For distant stars, as observed by the NASA Kepler satellite, parallax information is currently of fairly low quality and is not complete. This limits the precision with which the absolute sizes of the stars and their potential transiting planets can be determined by traditional methods. Asteroseismology will be used to aid the radius determination

Radial velocity studies have provided the majority of all exoplanet discoveries. Using the radial velocity techniques on young stars suffers from problems with magnetic activity jitter, which has been studied for years, and the effects of circumstellar disks, which has remained unstudied. Here we study the disk-embedded star BP Psc using high

Context: Ultra-cool dwarfs of the L spectral type (T_eff = 1400-2200 K) are known to have dusty atmospheres. Asymmetries of the dwarf surface may arise from rotationally-induced flattening and dust-cloud coverage, and may result in non-zero linear polarisation through dust scattering. Aims: We aim to study the heterogeneity of ultra-cool dwarfs'

We present near-infrared linear spectropolarimetry of a sample of persistent X-ray binaries, Sco X-1, Cyg X-2 and GRS 1915+105. For Sco X-1 and Cyg X-2, the polarization levels at 2.4 μm are 1.3+/-0.10% and 5.4+/-0.7%, respectively, which is greater than the polarization level at 1.65 μm. This cannot be explained by interstellar polarization or

For about a decade, spectropolarimetry of He I λ10830 has been applied to the magnetic diagnostics of the solar chromosphere. This resonance line is very versatile as it is visible both on disk and in off-limb structures, and it has a good sensitivity to both the weak-field Hanle effect and the strong-field Zeeman effect. Recent observations of an

The use of AO in Extremely Large Telescopes, used to improve performances in smaller telescopes, becomes now mandatory to achieve diffraction limited images according to the large apertures. On the other hand, the new dimensions push the specifications of the AO systems to new frontiers where the order of magnitude in terms of computation power