Multiwavelength optical observations of chromospherically active binary systems - III. High resolution echelle spectra from Ca ii H & K to Ca ii IRT

Astronomy and Astrophysics Supplement Series, Jul 2018

This is the third paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. High resolution echelle spectra including all the optical chromospheric activity indicators from the Ca ii H & K to Ca ii IRT lines are analysed here for 16 systems. The chromospheric contribution in these lines has been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted Hα profile of the very active star HU Vir. These profiles are well matched using a two-component Gaussian fit (narrow and broad) and the broad component can be interpreted as arising from microflaring. Red-shifted absorption features in the Hα line have been detected in several systems and excess emission in the blue wing of FG UMa was also detected. These features indicate that several dynamical processes, or a combination of them, may be involved. Using the ratio as a diagnostic we have detected prominence-like extended material viewed off the limb in many stars of the sample, and prominences viewed against the disk at some orbital phases in the dwarfs OU Gem and BF Lyn. The He i D3 line has been detected as an absorption feature in mainly all the giants of the sample. Total filling-in of the He i D3, probably due to microflaring activity, is observed in HU Vir. Self-absorption with red asymmetry is detected in the Ca ii H & K lines of the giants 12 Cam, FG UMa and BM CVn. All the stars analysed show clear filled-in Ca ii IRT lines or even notable emission reversal. The small values of the ratio we have found indicate Ca ii IRT emission arises from plage-like regions. Orbital phase modulation of the chromospheric emission has been detected in some systems, in the case of HU Vir evidence of an active longitude area has been found.

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Multiwavelength optical observations of chromospherically active binary systems - III. High resolution echelle spectra from Ca ii H & K to Ca ii IRT

Astron. Astrophys. Suppl. Ser. Multiwavelength optical observations of chromospherically active binary systems III. High resolution echelle spectra from Ca ii H K to Ca ii IRT? D. Montes 1 2 M.J. Fernandez-Figueroa 2 E. De Castro 2 M. Cornide 2 A. Latorre 2 J. Sanz-Forcada 0 2 0 Harvard-Smithsonian Center for Astrophysics , 60 Garden St., Cambridge, MA 02138 , U.S.A 1 Guest observer at McDonald Observatory , Texas , U.S.A 2 Departamento de Astrof sica, Facultad de Ciencias F sicas, Universidad Complutense de Madrid , E-28040 Madrid , Spain This is the third paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. High resolution echelle spectra including all the optical chromospheric activity indicators from the Ca ii H & K to Ca ii IRT lines are analysed here for 16 systems. The chromospheric contribution in these lines has been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted H pro le of the very active star HU Vir. These pro les are well matched using a two-component Gaussian t (narrow and broad) and the broad component can be interpreted as arising from microflaring. Red-shifted absorption features in the H line have been detected in several systems and excess emission in the blue wing of FG UMa was also detected. These features indicate that several dynamical processes, or a combination of them, may be involved. Using the EH =EH ratio as a diagnostic we have detected prominence-like extended material viewed o the limb in many stars of the sample, and prominences viewed against the disk at some orbital phases in the dwarfs OU Gem and BF Lyn. The He i D3 line has been detected as an absorption feature in mainly all the giants of the sample. stars; activity | stars; binaries; close | stars; binaries; spectroscopic | stars; chromospheres | stars; late-type - Send o print requests to: D. Montes ? Based on observations made with the Isaac Newton Telescope (INT) operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrof sica de Canarias, and with the Nordic Optical Telescope (NOT), operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof sica de Canarias. ?? Tables 3, 5, 6, 7 also at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.ustrasbg.fr/Abstract.html Correspondence to: e-mail: dmg@astrax. s.ucm.es Total lling-in of the He i D3, probably due to microflaring activity, is observed in HU Vir. Self-absorption with red asymmetry is detected in the Ca ii H & K lines of the giants 12 Cam, FG UMa and BM CVn. All the stars analysed show clear lled-in Ca ii IRT lines or even notable emission reversal. The small values of the E8542=E8498 ratio we have found indicate Ca ii IRT emission arises from plage-like regions. Orbital phase modulation of the chromospheric emission has been detected in some systems, in the case of HU Vir evidence of an active longitude area has been found. 1. Introduction This paper is a continuation of our ongoing project of multiwavelength optical observations aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features that are formed at di erent heights in the chromosphere. In Paper I (Montes et al. 1997) we focussed our study on the analysis of the extensively used H chromospheric activity indicator together with simultaneous observations of the less studied He i D3 and Na i D1, D2 spectral features in a sample of 18 northern active binary systems. In Paper II (Montes et al. 1998a) the H , H , Na i D1, D2, He i D3, Mg i b triplet, Ca ii H & K and Ca ii infrared triplet lines (Ca ii IRT) of the RS CVn system EZ Pegasi were studied at di erent orbital phases, also including a high resolution echelle spectrum. As shown in Papers I and II, with the simultaneous analysis of the di erent optical chromospheric activity indicators and using the spectral subtraction technique, it is possible to study in detail the chromosphere, discriminating between the di erent structures: plages, prominences, flares and microflares (see recent studies by Gunn & Doyle 1997; Gunn et al. 1997; Lazaro & Arevalo 1997; Arevalo & Lazaro 1999; Hall & Wolovitz 1998; Montes et al. 1998b; Montes & Ramsey 1998, 1999; Montes et al. 1999; Eibe et al. 1999; Oliveira & Foing 1999; Berdyugina et al. 1999) . In this paper we present high resolution echelle spectra of 16 systems selected from \A Catalog of Chromospherically Active Binary Stars (second edition)" (Strassmeier et al. 1993, hereafter CABS) . The spectra were taken during four observing runs (from 1996 to 1999) and include all the optical chromospheric activity indicators from the Ca ii H & K to C (...truncated)


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D. Montes, M. J. Fernández-Figueroa, E. De Castro, M. Cornide, A. Latorre, J. Sanz-Forcada. Multiwavelength optical observations of chromospherically active binary systems - III. High resolution echelle spectra from Ca ii H & K to Ca ii IRT, Astronomy and Astrophysics Supplement Series, pp. 103-140, Volume 146, Issue 1, DOI: 10.1051/aas:2000359