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Fe II Fluorescence in Symbiotic Stars

Published online by Cambridge University Press:  22 February 2018

M. Eriksson
Affiliation:
Atomic Astrophysics, Lund Observatory, Lund University, Box 43, SE-221 00, Lund, Sweden. ([email protected]) University College of Kalmar, SE-391 82, Kalmar, Sweden. (email:[email protected])
H. Veenhuizen
Affiliation:
University College of Kalmar, SE-391 82, Kalmar, Sweden. (email:[email protected])
G.M. Wahlgren
Affiliation:
Atomic Astrophysics, Lund Observatory, Lund University, Box 43, SE-221 00, Lund, Sweden. ([email protected])
S. Johansson
Affiliation:
Atomic Astrophysics, Lund Observatory, Lund University, Box 43, SE-221 00, Lund, Sweden. ([email protected])

Abstract

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Fe II fluorescence by PAR has been investigated in eight symbiotic stars having a wide range in temperature of the hot component and orbital period. The data used are spectra obtained from the IUE archive. All pumping lines investigated in this work are in the short wavelength region of IUE (1200-2000 Å), except for He ɪɪ λ1084.942 and O VI λ1032.041. The resulting Fe ɪɪ fluorescence lines are mainly in the long wavelength region (2000-3300 Å), but a few fall in the same region as the pumping lines. The aim is to understand the optimal conditions for formation of Fe ɪɪ fluorescence lines caused by PAR. Three of the selected systems, RR Tel, AG Peg and V1016 Cyg, have 10-30 active Fe ɪɪ channels. Two conditions connect those systems to each other: The hot component is a white dwarf of extreme temperature (80·103-150·103 K) and all three systems are so called symbiotic novae and have had outbursts during the last 150 years. Three systems, AG Dra, RW Hya and R Aqr, have only 2-3 active Fe ɪɪ channels. In the two remaining systems, CI Cyg and T CrB, Fe ɪɪ fluorescence lines were totally absent. These two systems have two features in common: The emission strength of highly ionized elements is less than in most symbiotic systems, and the hot component is suspected to be an accreting main sequence star rather than a white dwarf.

Resumen

Resumen

Se ha investigado la fluorescencia por PAR del ion Fe II en ocho estrellas simbióticas con muy diversos valores de la temperatura de la componente caliente y del período orbital. Los datos empleados son espectros de archivo del IUE. Todas las líneas de bombeo estudiadas se encuentran en la región (1200-2000 Å) del IUE, excepto He ɪɪ λ1084.942 y O VI λ1032.041. Las líneas de fluorescencia del Fe ɪɪ están principalmente en la región Fe ɪɪ, pero algunas caen en la región de las líneas de bombeo. Nuestro objetivo es entender las condiciones óptimas para la formación de líneas de fluorescencia por PAR del FeII. Tres de los sistemas estudiados, RR Tel, AG Peg and V1016 Cyg, presentan 10-30 canales activos del FeII. Dos condiciones relacionan a estos sistemas. La componente caliente es una enana blanca de temperatura extrema (80·103-150·103 K), y los tres sistemas son novas simbióticas, que han tenido erupciones en los últimos 150 años. Los sistemas AG Dra, RW Hya and R Aqr tienen sólo 2-3 canales activos del Fe ɪɪ. Los dos sistemas restantes, CI Cyg and T CrB, no mostraron líneas de fluorescencia del Fe II. Estos sistemas tienen en común que la intensidad de emisión de los elementos altamente ionizados es menor que en la mayoría de los sistemas simbióticos, y que la componente caliente puede ser una estrella de secuencia principal con acreción, en vez de una enana blanca.

Type
Observational Results for Very Young Binaries
Copyright
Copyright © Instituto de Astronomia – Mexico 2004

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