RT Journal Article
T1 The behaviour of the excess Ca II H and K and H_ε emissions in chromospherically active binaries
A1 Montes Gutiérrez, David
A1 Fernández Figueroa, María José
A1 Cornide Castro-Piñeiro, Manuel
A1 Castro Rubio, Elisa De
AB In this work we analyze the behaviour of the excess Ca II H and K and H_ ε emissions in a sample of 73 chromospherically active binary systems (RS CVn and BY Dra classes), of different activity levels and luminosity classes. This sample includes the 53 stars analyzed by Fernandez-Figueroa et al. (1994) and the observations of 28 systems described by Montes et al. (1995c). By using the spectral subtraction technique (subtraction of a synthesized stellar spectrum constructed from reference stars of spectral type and luminosity class similar to those of the binary star components) we obtain the active-chromosphere contribution to the Ca II H and K lines in these 73 systems. We have determined the excess Ca II H and K emission equivalent widths and converted them into surface fluxes. The emissions arising from each component were obtained when it was possible to deblend both contributions. We have found that the components of active binaries are generally stronger emitters than single active stars for a given effective temperature and rotation rate. A slight decline of the excess Ca II H and K emissions towards longer rotation periods, P-rot, and larger Rossby numbers, R_0, is found. When we use R_0  instead of P_rot, the scatter is reduced and a saturation at R_0≈0.3 is observed. A good correlation between the excess Ca II K and H_ ε chromospheric emission fluxes has been found. The correlations obtained between the excess Ca II K emission and other activity indicators, (C IV in the transition region, and X-rays in the corona) indicate that the exponents of the power-law relations increase with the formation temperature of the spectral features.
PB EDP Sciencies
SN 0004-6361
YR 1996
FD 1996-08
LK https://hdl.handle.net/20.500.14352/59620
UL https://hdl.handle.net/20.500.14352/59620
LA eng
NO © 1996 EDP Sciencies.We thank F. Martín for the C iv ux measurements in IUE spectra retrieved from ULDA. We would also like to thank Dr. B. Montesinos for the very careful reading of the manuscript and the referee S. Catalano for suggesting several improvements and clarifications. This work has been supported by the Universidad Complutense de Madrid and the Spanish Dirección General de Investigación Científica y Técnica (DGICYT) under grant PB94-0263.
NO Universidad Complutense de Madrid (UCM)
NO Dirección General de Investigación Científica y Técnica (DGICYT), España
NO Ministerio de Economía y Competitividad (MINECO), España
DS Docta Complutense
RD 13 abr 2025