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

BUCCINO, A.P.; DÍAZ, R.F.; LUONI, M.L.; ABREVAYA, X.C.; MAUAS, P.J.D.

ASTRONOMICAL JOURNAL

IOP PUBLISHING LTD

Año: 2011 p. 1 - 7

0004-6256

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 theirsmall intrinsic brightness, M dwarfs are not usually the targets of long-termobservational studies of stellar activity, and their long-term variability is generallynot known. In this work, we study the long-term activity of two Mdwarf stars: Gl 229 A (M1/2) and Gl 752 A (M2.5). We employ mediumresolution echelle spectra obtained at the 2.15 m telescope at the Argentinianobservatory CASLEO between the years 2000 and 2010 and photometric observationsobtained from the ASAS database. We analyzed Ca II K line-corefluxes and the mean V magnitude with the Lomb-Scargle periodogram, andwe obtain possible activity cycles of ∼4 yr and ∼7 yr for Gl 229 A and Gl 752A respectively.