First long-term activity study of AU Microscopii: a possible chromospheric cycle
Date Issued
2019
Author(s)
Ibañez, R. V.
•
Buccino, A. P.
•
Flores, M.
•
Martinez, C. I.
•
Maizel, D.
•
•
Mauas, P. J. D.
Abstract
M stars are ideal targets to search for Earth-like planets. However, they
usually have high levels of magnetic activity, which could affect their
habitability and make difficult the detection of exoplanets orbiting around
them. Unfortunately, long-term variability of dM stars has not been extensively
studied, due to their low intrinsic brightness. For this reason, in 1999 we
started the HKalpha project, which systematically observes the spectra of a
large number of stars, in particular dM stars, at the Complejo Astronomico El
Leoncito (CASLEO). In this work, we study the long-term activity of the young
active dM1 star AU Microscopii. We analyze the Mount Wilson index S derived
from CASLEO spectra obtained between 2004 and 2016, which we complement with
the S-index derived from HARPS, FEROS and UVES public spectra. We also analyze
the simultaneous photometric counterpart provided by the ASAS public database
for this star between 2000 and 2009, and our own photometry. In both totally
independent time series, we detect a possible activity cycle of period around 5
years. We also derived a precise rotation period for this star P rot = 4.85
days, consistent with the literature. This activity cycle reflects that an
alphaOmega dynamo could be operating in this star.
Volume
483
Issue
1
Start page
1159
Issn Identifier
0035-8711
Rights
open.access
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