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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Is the primary CoRoT target HD 43587 under a Maunder minimum phase?

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Ferreira, R. R. [1] ; Barbosa, R. [2] ; Castro, M. [1] ; Guerrero, G. [2] ; de Almeida, L. [1] ; Boumier, P. [3] ; do Nascimento, Jr., J. -D. [4, 1]
Total Authors: 7
[1] Univ Fed Rio Grande do Norte, Dept Fis Teor & Expt, BR-59072970 Natal, RN - Brazil
[2] Univ Fed Minas Gerais, Dept Fis, Ave Antonio Carlos 6627, BR-31270901 Belo Horizonte, MG - Brazil
[3] Univ Paris Saclay, Inst Astrophys Spatiale, UMR8617, CNRS, F-91405 Orsay - France
[4] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 - USA
Total Affiliations: 4
Document type: Journal article
Source: Astronomy & Astrophysics; v. 640, AUG 10 2020.
Web of Science Citations: 0

Context. One of the most enigmatic phenomena related to solar activity is the so-called Maunder minimum phase. It consists in the lowest sunspot count ever registered for the Sun and has not been confirmed for other stars to date. Since the spectroscopic observations of stellar activity at the Mount Wilson Observatory, the solar analog HD 43587 has shown a very low and apparently invariant activity level, which makes it a Maunder minimum candidate.Aims. We aim to analyze the chromospheric activity evolution of HD 43587 and its evolutive status, with the intention of unraveling the reasons for this low and flat activity.Methods. We used an activity measurements dataset available in the literature, and computed the S-index from HARPS and NARVAL spectra to infer a cycle period. Additionally, we analyzed the CoRoT light curve of HD 43587, and applied gyrochronology and activity calibrations to determine its rotation period. Finally, based on an evolutionary model and the inferred rotation period, we used the EULAG-MHD code to perform global MHD simulations of HD 43587 to get some insight into its dynamo process.Results. We confirm the almost flat activity profile, with a cycle period P-cyc=10.443.03 yr deduced from the S-index time series, and a long-term trend that might be a period of more than 50 yr. It was impossible to define a rotation period from the light curve, however gyrochronology and activity calibrations allow us to infer an indirect estimate of P-<overbar>(rot) = 22.6 +/- 1.9 P overbar mml:mover rot = 22.6 mml:mo +/- 1.9 d. Furthermore, the MHD simulations confirm an oscillatory dynamo with a cycle period in good agreement with the observations and a low level of surface magnetic activity.Conclusions. We conclude that this object might be experiencing a ``natural{''} decrease in magnetic activity as a consequence of its age. Nevertheless, the possibility that HD 43587 is in a Maunder minimum phase cannot be ruled out. (AU)

FAPESP's process: 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center
Grantee:Elisabete Maria de Gouveia Dal Pino
Support type: Multi-user Equipment Program