1997/08/25 by Axel D. Schwope, AD Schwope, Schwope, Axel D. +36
Chemistry · Engineering · Physics and Astronomy · #Advanced Fiber Optic Sensors #Astrophysics (astro-ph) #FOS: Physical sciences #Photonic and Optical Devices #Spectroscopy and Laser Applications #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9708228
15 pages, 9 figures, LaTeX, uses paspconf.sty and epsf.sty; Invited review given at the 13th North American Workshop on CVs, ASP Conf. Ser., in press; see also http://www.aip.de:8080/~preprint/preprints/1997/1997_ads4.html
arxiv created 1997/08/25 · openalex publication_date 1997/08/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We review the main observational characteristics of AM Herculis stars (polars) at X-ray, EUV, UV, IR and optical wavelengths. Particular emphasis is given to multi-epoch, multi-wavelength observations of the eclipsing polar HU Aqr (RX J2107.9-0518). In AM Herculis stars the broad-band spectral energy distribution from X-rays to the IR is governed by only very small structures: the hot accretion regions on the footpoints af accreting field lines. The most extended structures in the binary systems on the other hand, the mass-donating secondary stars and the accretion streams, distinctly appear only as Doppler-shifted emission or absorption lines. They can best be studied by investigating selected narrow spectral features in the optical, ultraviolet or the near infrared. In this contribution both aspects will be highlighted, the structure of the accretion regions as inferred from multi-wavelength observations with low or no spectral resolution, as well as the structure of the secondary stars and the accretion streams as inferred from high-resolution spectral observations and Doppler mapping.