I studied Physics at the Complutense University in Madrid (Spain) and I got my doctoral degree at the Autónoma University in Madrid in 1993. I worked on my Ph.D. Thesis, "Stellar formation: variability of pre-main sequence stars", under the supervision of Carlos Eiroa. I have been working abroad (outside Spain) for seven years: two years at the Institute for Astronomy of the University "Nacional Autonóma" of México (UNAM) and five years in Germany, at the Max Planck Institute for Astronomy, in Heidelberg, and at the Max Planck Institute for Extraterrestrial Physics, in Garching, close to Munich. I have worked more than 20 years at the Institute for Astrophysics of Andalusia (IAA, CSIC), in Spain. Since 2008 I am a staff member and from May 1, 2009, until June 11, 2013, I was director of the Institute. During these four years the IAA-CSIC had over 200 members and was in charge of the Sierra Nevada Observatory and (together with the MPIA in Heidelberg) of the Calar Alto Observatory (Almería, Spain). I work mainly on low mass stars, that is, stars with a mass similar to the Sun or smaller. I study the last stages of their formation, when the gas and dust disk that has surrounded them during the accretion stage is close to an end. This is the disk in which planets and minor bodies will be formed. The accretion process and the stellar activity (magnetic activity) are responsible for the variability that characterizes these stars. From the study of their variability we learn about the stars and their disks. My main scientific achievements have been: - my contribution to one of the two papers that gave basis to the binomial distribution of the rotational periods of low-mass pre-main sequence stars (Bouvier et al. 1993). This distribution is the starting point for the studies of evolution of the angular momentum of low mass stars. - the detection, for the first time, of a jet from an object at the substellar limit (Fernandez & Comeron 2005). - the detailed study of the young star V410 Tau (Stelzer et al. 2003, Fernandez et al. 2004). We confirmed observationally that the energy dissipated during flares was above the threshold given by theoretical models that tried to explain the formation of meteorites in the early Solar System. - my work done in the field of mass accretion onto pre-main sequence stars, finding relations between the mass accretion indicators and other stellar parameters. In 2007 I joined, as co-Principal Investigator, the team that has built the wide field infrared camera PANIC for the 2.2m and 3.5m telescopes of the Calar Alto Observatory. The camera is a collaboration between the Max Planck Institute for Astronomy (MPIA), in Heidelberg, and the Institute for Astrophysics of Andalusia. The camera works under cryogenic conditions (at about 100K) and it covers the maximum non-vignetted field of view at the 2.2m telescope, 30'x30'. The commissioning and the science verification finished in 2015. Due to the degradation of three of the four PANIC detectors that form a 2x2 mosaic, the mosaic has been replaced by a monolithic 4kx4k near-infrared detector. In December 2022 a new commissioning started and we are now checking the alignment of the focal plane. I have supervised the PhD thesis of Estefania Casal Lopez, entitled "Position on the Hertzprung-Russell diagram of magnetically active young stars", that has tackled the fact that low mass stars (below 2 solar masses) arrive at the main sequence showing noticeable brightness variations on time scales of days, weeks and even years. Since the exact location of a star on the Hertzprung-Russell (HR) diagram allows us to determine, using evolutionary tracks, stellar parameters such as mass, temperature, age or metallicity, the variability adds uncertainty to the values of these parameters. The characterization of this effect has been the subject of the PhD work. I have published 70 papers on refereed journals and 83 papers on other journals or proceedings. I have given over 30 talks at meetings or at scientific institutions. Number of citations: 3923 (H factor=34 and H_norm=13). Ten of my most relevant and recent contributions related to the theme of the proposal are: 1.- Title: Planet-star interactions with precise transit timing. III. Entering the regime of dynamical tides Authors: Maciejewski, G.; Fernández, M.; Sota, A.; Amado, P. J.; et al. Astronomy & Astrophysics, Volume 667, id.A127 (2022) 2.- Title: Photodynamical analysis of the nearly resonant planetary system WASP-148. Accurate transit-timing variations and mutual orbital inclination Authors: Almenara, J. M.; Hébrard, G.; Díaz, R. F.; Laskar, J.; Correia, A. C. M.; Anderson, D. R.; Boisse, I.; Bonfils, X.; Brown, D. J. A.; Casanova, V.; Cameron, A. Collier; Fernández, M.; Jenkins, J. M. et al. Astronomy & Astrophysics, Volume 663, id.A134 (2022) 3.- Title: The CARMENES search for exoplanets around M dwarfs. Benchmarking the impact of activity in high-precision radial velocity measurements Authors: Jeffers, S. V.; Barnes, J. R.; Schöfer, P.; Quirrenbach, A.; Zechmeister, M.; Amado, P. J.; Caballero, J. A.; Fernández, M.; Rodríguez, E.; et al. Astronomy & Astrophysics, Volume 663, id.A27 (2022) 4.- Title: Revisiting TrES-5 b: departure from a linear ephemeris instead of short-period transit timing variation Authors: Maciejewski, G.; Fernández, M.; Aceituno, F.; Ramos, J. L.; Dimitrov, D.; Donchev, Z.;Ohlert, J. Astronomy & Astrophysics, Volume 656, id.A88, pp. (2021) 5.- Title: Fast-rotating giant stars behind the Coma Berenices star cluster Authors: Casal, Estefanía; Fernández, Matilde; Alfaro, Emilio J.; Casanova, Víctor; Tobaruela, Ángel Monthly Notices of the Royal Astronomical Society, 497, 2562 (2020) 6.- Title: PANIC: A General-purpose Panoramic Near-infrared Camera for the Calar Alto Observatory Authors: Cárdenas Vázquez, M.-C.; Dorner, B.; Huber, A.; et al. [my position is num.13] Publications of the Astronomical Society of the Pacific, 130, 025003, 17 pp. (2018) 7.- Title: YETI observations of the young transiting planet candidate CVSO 30 b Authors: Raetz, St.; Schmidt, T. O. B.; Czesla, S.; Klocová, T.; Holmes, L.; Errmann, R.; Kitze, M.; Fernandez et al. Monthly Notices of the Royal Astronomical Society, 460, 2834-2852 (2016) 8.- Title: Departure from the constant-period ephemeris for the transiting exoplanet WASP-12 Authors: Maciejewski, G.; Dimitrov, D.; Fernandez, M.; et al. Astronomy & Astrophysics, 588, id.L6, 6 pp. (2016) 9.- Title: WASP-14 b: transit timing analysis of 19 light curves Authors: Raetz, St.; Maciejewski, G.; Seeliger, M.; Marka, C.; Fernandez, et al. Monthly Notices of the Royal Astronomical Society, 451, 4139-4149 (2015) 10.- Title: No variations in transit times for Qatar-1 b Authors: Maciejewski, G.; Fernández, M.; Aceituno, F. J.; et al. Astronomy & Astrophysics, 577, id.A109, 7 pp. (2015)