Toledo-Padrón, B.; González Hernández, J. I.; Rodríguez-López, C.; Suárez Mascareño, A.; Rebolo, R.; Butler, R. P.; Ribas, I.; Anglada-Escudé, G.; Johnson, E. N.; Reiners, A.; Caballero, J. A.; Quirrenbach, A.; Amado, P. J.; Béjar, V. J. S.; Morales, J. C.; Perger, M.; Jeffers, S. V.; Vogt, S.; Teske, J.; Shectman, S.; Crane, J.; Díaz, M.; Arriagada, P.; Holden, B.; Burt, J.; Rodríguez, E.; Herrero, E.; Murgas, F.; Pallé, E.; Morales, N.; López-González, M. J.; Díez Alonso, E.; Tuomi, M.; Kiraga, M.; Engle, S. G.; Guinan, E. F.; Strachan, J. B. P.; Aceituno, F. J.; Aceituno, J.; Casanova, V. M.; Martín-Ruiz, S.; Montes, D.; Ortiz, J. L.; Sota, A.; Briol, J.; Barbieri, L.; Cervini, I.; Deldem, M.; Dubois, F.; Hambsch, F.-J.; Harris, B.; Kotnik, C.; Logie, L.; Lopez, J.; McNeely, M.; Ogmen, Y.; Pérez, L.; Rau, S.; Rodríguez, D.; Urquijo, F. S.; Vanaverbeke, S.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 488, Issue 4, p.5145-5161
Description
The search for Earth-like planets around late-type stars using
ultrastable spectrographs requires a very precise characterization of
the stellar activity and the magnetic cycle of the star, since these
phenomena induce radial velocity (RV) signals that can be misinterpreted
as planetary signals. Among the nearby stars, we have selected Barnard's
Star (Gl 699) to carry out a characterization of these phenomena using a
set of spectroscopic data that covers about 14.5 yr and comes from seven
different spectrographs: HARPS, HARPS-N, CARMENES, HIRES, UVES, APF, and
PFS; and a set of photometric data that covers about 15.1 yr and comes
from four different photometric sources: ASAS, FCAPT-RCT, AAVSO, and
SNO. We have measured different chromospheric activity indicators (H
α, Ca II HK, and Na I D), as well as the full width at
half-maximum (FWHM), of the cross-correlation function computed for a
sub-set of the spectroscopic data. The analysis of generalized
Lomb-Scargle periodograms of the time series of different activity
indicators reveals that the rotation period of the star is 145 ±
15 d, consistent with the expected rotation period according to the low
activity level of the star and previous claims. The upper limit of the
predicted activity-induced RV signal corresponding to this rotation
period is about 1 m s-1. We also find evidence of a long-term
cycle of 10 ± 2 yr that is consistent with previous estimates of
magnetic cycles from photometric time series in other M stars of similar
activity levels. The available photometric data of the star also support
the detection of both the long-term and the rotation signals.
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Jonay Isai
González Hernández
