The CARMENES search for exoplanets around M dwarfs: Period search in H α, Na i D, and Ca II IRT lines

We use spectra from CARMENES, the Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs, to search for periods in chromospheric indices in 16 M0-M2 dwarfs. We measure spectral indices in the Hα, the Ca II infrared triplet (IRT), and the N...

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Detalhes bibliográficos
Autores: Fuhrmeister, Birgit, Czesla, S., Schmitt, Jürgen H. M. M., Johnson, E.N., Schöfer, P., Jeffers, Sandra V., Caballero, J. A., Zechmeister, Mathias, Reiners, Ansgar, Ribas, Ignasi, Amado, Pedro J., Quirrenbach, Andreas, Bauer, Florian Franz, Béjar, Victor J. S., Cortés-Contreras, M., Díez-Alonso, E., Dreizler, Stefan, Galadí-Enriquez, D., Guenther, E. W., Kaminski, Adrian, Kürster, M., Lafarga, M., Montes, David
Formato: artículo
Estado:Versión publicada
Fecha de publicación:2019
País:España
Recursos:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/185676
Acesso em linha:http://hdl.handle.net/10261/185676
Access Level:acceso abierto
Palavra-chave:Stars: rotation
Stars: activity
Stars: chromospheres
Stars: late-type
Descrição
Resumo:We use spectra from CARMENES, the Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs, to search for periods in chromospheric indices in 16 M0-M2 dwarfs. We measure spectral indices in the Hα, the Ca II infrared triplet (IRT), and the Na I D lines to study which of these indices are best-suited to finding rotation periods in these stars. Moreover, we test a number of different period-search algorithms, namely the string length method, the phase dispersion minimisation, the generalized Lomb-Scargle periodogram, and the Gaussian process regression with quasi-periodic kernel. We find periods in four stars using Hα and in five stars using the Ca II IRT, two of which have not been found before. Our results show that both Hα and the Ca II IRT lines are well suited for period searches, with the Ca II IRT index performing slightly better than Hα. Unfortunately, the Na I D lines are strongly affected by telluric airglow, and we could not find any rotation period using this index. Further, different definitions of the line indices have no major impact on the results. Comparing the different search methods, the string length method and the phase dispersion minimisation perform worst, while Gaussian process models produce the smallest numbers of false positives and non-detections.© 2019 ESO.

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