The surprising Far-UV spectrum of the polar BY Camelopardalis - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2003

The surprising Far-UV spectrum of the polar BY Camelopardalis

J. -M. Bonnet-Bidaud
  • Fonction : Auteur
K. Beuermann
  • Fonction : Auteur
D. de Martino
  • Fonction : Auteur
R. E. Fried
  • Fonction : Auteur
B. T. Gänsicke
  • Fonction : Auteur
S. B. Howell
  • Fonction : Auteur
K. Mukai
  • Fonction : Auteur
D. Porquet
  • Fonction : Auteur
P. Szkody
  • Fonction : Auteur

Résumé

We report on the first far-UV observations of the asynchronous polar BY Cam made by the Far-Ultraviolet Spectroscopic Explorer (FUSE). The source is known to exhibit the most extreme NV/CIV emission resonance line ratio observed among polars. The FUSE observations reveal a OVI resonance line weaker than in the prototype of polars, AM Her, with the absence of a detectable narrow component. The OVI broad line is detected with an equivalent width of the same order as in AM Her, the blueward doublet component is clearly present but the redward component is strongly affected by H2 absorption. The presence of a strong NIII line and weak CIII lines also confirms the peculiar CNO line flux. We compare the resonance CNO line intensities with the predictions of the CLOUDY plasma code coupled to a geometrical model of the accretion column. Varying the temperature and/or intensity of the ionising spectrum is unable to reproduce the observed broad line ratios. A solution is obtained by significantly altering the element abundances with a strong depletion of C, overabundance of N and a weak underabundance of O. This confirms previous suggestions of non-solar abundances which may result from redistribution in the accreted material following nova outbursts and/or the secondary nuclear evolution. A very significant H2 absorption is observed in front of the source, a possible indication for either the existence of a dense interstellar cloud or of circumstellar material.

This work is based on data obtained from the NASA-CNES-CSA FUSE mission.

Fichier principal
Vignette du fichier
aah4229.pdf (133.95 Ko) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-04111249 , version 1 (08-06-2023)

Identifiants

Citer

M. Mouchet, J. -M. Bonnet-Bidaud, E. Roueff, K. Beuermann, D. de Martino, et al.. The surprising Far-UV spectrum of the polar BY Camelopardalis. Astronomy and Astrophysics - A&A, 2003, 401, pp.1071-1076. ⟨10.1051/0004-6361:20030176⟩. ⟨hal-04111249⟩
18 Consultations
3 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More