Data: 11.08.2022

Palestrante: Dr. Andrea Buccino (Universidad de Buenos Aires)

Link: https://youtu.be/tSwuA2F02ZY

Slides:

Resumo: The Mount Wilson survey is the most extended database to explore the long-term chromospheric activity in F to K stars. However, activity in southern late-type stars and beyond the convective limit (~M3.5) has not been extensively explored by this program. Over the last decade, new interest in M dwarfs has emerged. They are prime targets for current and upcoming exoplanet searches and characterization efforts, due to their ubiquity in the solar neighborhood and high occurrence rates of small exoplanets in the habitable zone. However, these stars can be very active and their activity signatures can hinder the detection of orbiting planets. To analyze the long-term activity in late-type stars near and beyond the convective limit, since 1999 the HKα Project has been operating in the Argentine CASLEO (Complejo Astronómico El Leoncito) observatory. We systematically observe more than 150 main-sequence southern stars from F3 to M5.5. To date, we have more than 6000 mid-resolution spectra, ranging from 389 to 669 nm, which constitute an ideal dataset to study long-term activity in cool stars. In this talk I will revise the main results of the HKα Project. First, I show evidence of cyclic activity for M dwarfs, including fully-convective stars. Then, I concentrate on multiple cycles in solar-type stars and the interpretation from the dynamo theory.