The Gran Telescopio de Canarias Adaptive Optics System (GTCAO) is currently in its commissioning phase at Roque de Los Muchachos Observatory (ORM). The GTCAO is a single-conjugated post-focal system equipped with a Shack- Hartmann Wavefront Sensor (WFS) and a Deformable Mirror (DM) conjugated to the pupil, achieving a Strehl Ratio of 65% in the K

We present an exhaustive photometric and spectroscopic analysis of TOI-837, a F9/G0 35 Myr young star, hosting a transiting exoplanet, TOI-837 b, with an orbital period of ~8.32 d. Utilizing data from the Transiting Exoplanet Survey Satellite and ground-based observations, we determine a planetary radius of $0.818_{-0.024}^{+0.034}$ R J for TOI-837

Context. Small planets transiting bright nearby stars are essential to our understanding of the formation and evolution of exoplanetary systems. However, few constitute prime targets for atmospheric characterization, and even fewer are part of multiple star systems. Aims: This work aims to validate TOI-4336 A b, a sub-Neptune-sized exoplanet

This thesis focuses on the study of atmospheres of main sequence cool stars (spectral types G2V, K0V, and M2V, with solar metallicity) by means of three-dimensional time-dependent magneto-hydrodynamic simulations of their near-surface convection and photospheres. The simulations are computed with the MANCHA code, which is adapted to simulate other

One of the main goals of the NASA Transiting Exoplanet Survey Satellite (TESS) mission is the discovery of Earth-like planets around nearby M-dwarf stars. We present the discovery and validation of three new short-period Earth-sized planets orbiting nearby M dwarfs: TOI-5720 b, TOI-6008 b, and TOI-6086 b. We combined TESS data, ground-based

Ultra-diffuse galaxies (UDGs) are attractive candidates to probe cosmological models and test theories of galaxy formation at low masses; however, they are difficult to detect because of their low surface brightness. In the Local Group a handful of UDGs have been found to date, most of which are satellites of the Milky Way and M31, and only two are