paper

Long-term chromospheric activity in southern M dwarfs: Gl 229 A and Gl 752 A

arXiv:1011.1137 · doi:10.1088/0004-6256/141/2/34

Abstract

Several late-type stars present activity cycles similar to that of the Sun. However, these cycles have been mostly studied in F to K stars. Due to their small intrinsic brightness, M dwarfs are not usually the targets of long-term observational studies of stellar activity, and their long-term variability is generally not known. In this work, we study the long-term activity of two M dwarf stars: Gl 229 A (M1/2) and Gl 752 A (M2.5). We employ medium resolution echelle spectra obtained at the 2.15 m telescope at the Argentinian observatory CASLEO between the years 2000 and 2010 and photometric observations obtained from the ASAS database. We analyzed Ca \II K line-core fluxes and the mean V magnitude with the Lomb-Scargle periodogram, and we obtain possible activity cycles of 4 yr and 7 yr for Gl 229 A and Gl 752 A respectively.

Accepted for publication by Astronomical Journal (AJ)

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