~20 yr of stellar activity for M stars
M dwarf stars are prime targets in current and upcoming exoplanet surveys, due to their ubiquity in the
solar neighborhood and the high occurrence of small exoplanets in their habitable zones. However, their
magnetic activity could hinder the detection of orbiting planets and also seriously contrains the
habitability of the terrestrial planets.
During the last decade, new debates about the mechanism responsible for the magnetic activity of M stars
have emerged in the dynamo theory. Information on the long-term activity of partially and fully
convective M stars would allow us to understand whether their underlying dynamo is responsible for the
detected activity cycles.
Since 1999, the HKα Project is operating in the Argentinian observatory CASLEO (Complejo
Astronómico El Leoncito), exclusively dedicated to observe a set of F3V to M5.5V stars. To date, our
database presents more than 6000 mid-resolution spectra with a wavelength range from 389 to 669 nm,
which constitutes an ideal dataset to study long-term activity.
In the present work, we show the first evidence of activity cycles for a fully convective M
stars, Gl 729, obtained from reliabale time series of 20 year length.