2023MNRAS.518.3147K -
Mon. Not. R. Astron. Soc., 518, 3147-3163 (2023/January-2)
A study of the magnetic activity and variability of GJ 436.
KUMAR M. and FARES R.
Abstract (from CDS):
We present a magnetic activity study of GJ 436 using spectroscopic data from HARPS, spanning over 14 yr, and additional data from NARVAL, falling within the HARPS observations. We study the Ca II H&K, He I D3, Na I doublet, H α, and Ca II IRT triplets lines and explore linear correlations between them. Using the full HARPS data set, we found indices H α versus Ca II H&K & H α versus He I to correlate positively. From the NARVAL data set, covering one observing epoch, we found Ca II IRT3 versus Ca II IRT2 & Ca II IRT3 versus H α index to correlate negatively. We investigate long and short-term periodicity in these index variations, using the Generalized Lomb-Scargle periodogram. For Ca II H&K, Na I and H α indices, we detect long-term periods of 2470.7 d (∼ 6.8 yr), 1861.6 d (∼ 5.1 yr), and 2160.9 d (∼ 5.9 yr) respectively, consistent with GJ 436's photometric cycle of ∼ 7.4 yr. Applying the 'Pooled Variance' technique to H α & Na I indices, we found ∼ 2500 d to be the period of an activity cycle mechanism, in good agreement with the detected 2470.7 d period. For Ca II H&K and H α indices, we detect short-term periods of $39.47^{+0.11}_{-0.15}$ d and $40.46^{+0.44}_{-0.52}$ d, respectively, identified as the stellar rotation period. The stellar rotation is detected after pre-whitening the long-term periodicity. It is detected as well in the analysis of individual observing epochs.
Abstract Copyright:
© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
Journal keyword(s):
stars: activity - stars: chromospheres - stars: individual: GJ 436 - planetary systems
Status at CDS
:
Large table(s) will be appraised for possible ingestion in VizieR.
Simbad objects:
4
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2023MNRAS.518.3147K and select 'bookmark this link' or equivalent in the popup menu