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The CNO problem in Magnetic Cataclysmic Variables

Published online by Cambridge University Press:  12 April 2016

Jean-Marc Bonnet-Bidaud
Affiliation:
Service d’Astrophysique, DSM/DAPNIA/SAp, CEA Saclay, 91191 Gif-sur-Yvette, France
Martine Mouchet
Affiliation:
Observatoire de Paris, 92190 Meudon, France

Abstract

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Some polars like BY Cam are characterized by unusual CNO line ratios compared to other polars and non-solar abundances have been suggested to explain this anomaly. We present here a first attempt to constrain the elemental abundances in these systems by applying a specific ionisation model combined with a geometrical description of the accretion column where these lines are thought to be formed. The line luminosities have been computed using the CLOUDY plasma code for different ionisation spectra and column extension. We show here selected results and compare to the values observed in “peculiar” magnetic CVs. The model applied to BY Cam confirms that ionization models with solar abundances fail to reproduce the observed line intensity ratios. Assuming the model to be valid, the induced best abundances imply an overabundance of N (x25), underabundance of C (:8) and nearly solar O (:2), in line with CNO reprocessing.

Type
Part 3. A. Accretion Plasma diagnostics - Observations
Copyright
Copyright © Astronomical Society of the Pacific 2004

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