Multiwavelength optical observations of chromospherically active binary systems - II. EZ Pegasi



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Montes Gutiérrez, David and Sanz Forcada, J. and Fernández Figueroa, María José and Castro Rubio, Elisa de and Poncet, A. (1998) Multiwavelength optical observations of chromospherically active binary systems - II. EZ Pegasi. Astronomy & Astrophysics, 330 (1). pp. 155-168. ISSN 0004-6361

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The star EZ Peg, long ago classified as cataclysmic variable, has been shown to be a chromospherically active binary system of the RS CVn-type. In this paper we have analysed, using the spectral subtraction technique, simultaneous spectroscopic observations of the Hα, Hβ, Na I D_1 and D_2, He I D_3, Mg I b triplet, Ca II H & K, and Ca II infrared triplet lines. We have found that the hot component is the active star of the system, showing strong emission in the Hα, Ca Ir H & K, Hε, and Ca II IRT lines, and a strong filling-in of the Hβ line, however the Na I D_1 and D_2 and Mg I b triplet lines do not present filled-in. The He I D_3 could present a total filling-in due to microflaring. The observed variations (in different epochs and with the orbital phase) of the different activity indicators, formed at different height in the chromosphere, are correlated. Very broad wings have been found in the subtracted profiles of Hα and Ca II IRT λ8498 and λ8662 lines. These profiles are well matched using a two-component Gaussian fit (narrow and broad) and the broad component could be interpreted as arising from microflaring. The higher luminosity class of the hot component, that our spectra seem to indicate, could explain why the hot component is the active star of the system.

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© 1998 EDP Sciencies.
We thank N. Cardiel and J. Cenarro for having taken and reduced the 1997 JKT spectrum. This research has made use of La Palma Archive. This work has been supported by the Universidad Complutense de Madrid and the Spanish Direccion General de Investigación Científica y Técnica (DGICYT) under grant PB94-0263.

Uncontrolled Keywords:RS-canum-venaticorum; High-resolution spectrograph; H-alpha emission; Physical-properties; Lithium abundances; Infrared triplet; Line-profiles; CVN binaries; K-dwarfs; Stars
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:30978
Deposited On:18 Jun 2015 14:25
Last Modified:10 Dec 2018 15:05

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