A white dwarf with a low magnetic field in the IP RXJ0028.8+5917/V709Cas

J. M. Bonnet-Bidaud (1) , M. Mouchet (2) , D. de Martino , G. Matt , C. Motch (3)

1 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
2 DAEC - Departement d'Astrophysique Extragalactique et de Cosmologie
3 OAS - Observatoire astronomique de Strasbourg

We report the first detailed spectroscopic observations of the recently identified intermediate polar RXJ0028.8+5917/V709 Cas. We discovered that the system shows significant EW ~ (2-4)A broad absorptions, affecting the Balmer lines from Hdelta to Hbeta. These broad absorptions are interpreted as the contribution of an underlying DA logg=8 white dwarf at a temperature of ~ 23 000 K, contributing ~ 17 % (at 4500 A) to the overall flux. This is the first direct detection of a white dwarf in an intermediate polar system. The absence of significant Zeeman splitting indicates a magnetic field lower than 10 MG, confirming that, at least in some cases, intermediate polars have weaker fields than polars.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

J. M. Bonnet-Bidaud, M. Mouchet, D. de Martino, G. Matt, C. Motch. A white dwarf with a low magnetic field in the IP RXJ0028.8+5917/V709Cas. The Physics of Cataclysmic Variables and Related Objects, 2002, Göttingen, Germany. pp.133. ⟨hal-00010143⟩