According to dynamo theory, stars with convective envelopes efficiently generate surface magnetic fields, which manifest as magnetic activity in the form of starspots, faculae, and/or flares, when their rotation period is shorter than their convective turnover time. Most red giants, having undergone significant spin down while expanding, have slow

Mercator Array for Radial VELocities (MARVEL) is an ensemble of four 80-cm off the shelf telescopes feeding a single stabilised high-resolution (R>90 000) echelle spectrograph. The facility is currently under construction and will be located on La Palma (Canary Islands), next to the Mercator telescope. The facility is designed such that the four

Despite thousands of extrasolar planets discovered to date, the dominant mechanisms forming planets and the timescales of planetary migration and atmospheric evaporation remain to be probed observationally. To shed light on these mechanisms, we performed a combined photometric and spectroscopic analysis of several young transiting systems at

Metal-poor ultracool dwarfs (ultracool subdwarfs, including very-low-mass stars and brown dwarfs) are tracers of the pristine chemical composition at early phases in the assembly of the Milky Way. They are poorly understood because they are extremely faint and rare. Our aims are to improve the knowledge of ultracool subdwarf candidates, to break

MUDEHaR has completed its first of five years of project, and all the information is already available for exploitation. MUDEHaR is a multi-epoch photometric survey with two narrow filters in Hα and the calcium triplet window that uses T80Cam at the JAST80 telescope at Javalambre spanish astronomical observatory. It is obtaining ~50 epochs/year per

Simultaneous multicolor photometry is an important source of observational data providing priceless information on different physical processes that cannot be obtained in other ways. It can provide modal identification for classical pulsators, information about the stellar spots structure, or clues for identifying false positives in exoplanetary