A 150 MG Magnetic White Dwarf in the Cataclysmic Variable RX J1554.2+2721
Gänsicke, B. T.; Beuermann, K.; de Martino, D.; Szkody, P.; Jordan, S.; Marsh, T. R.; Thorstensen, J.
United Kingdom, Germany, Italy, United States
Abstract
We report the detection of Zeeman-split Lyα absorption π and σ+ lines in the far-ultraviolet Hubble Space Telescope/Space Telescope Imaging Spectrograph (STIS) spectrum of the magnetic cataclysmic variable RX J1554.2+2721. Fitting the STIS data with magnetic white dwarf model spectra, we derive a field strength of B~=144 MG and an effective temperature of 17,000 K<~Teff<~23,000 K. This measurement makes RX J1554.2+2721 only the third cataclysmic variable containing a white dwarf with a field exceeding 100 MG. Similar to the other high-field polar AR UMa, RX J1554.2+2721 is often found in a state of feeble mass transfer, which suggests that a considerable number of high-field polars may still remain undiscovered.
Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.