Open AccessIonization structure in accretion shocks with a composite cooling function
Author(s) -
Wu Kinwah,
Cropper Mark,
Ramsay Gavin
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04694.x
Subject(s) - physics , white dwarf , astrophysics , ionization , accretion (finance) , shock (circulatory) , shock wave , spectral line , line (geometry) , bremsstrahlung , emission spectrum , emissivity , astronomy , stars , nuclear physics , ion , mechanics , medicine , geometry , mathematics , optics , quantum mechanics , electron
We have investigated the ionization structure of the post‐shock regions of magnetic cataclysmic variables, using an analytic density and temperature structure model in which effects caused by bremsstrahlung and cyclotron cooling are considered. We find that in the majority of the shock‐heated region where H‐ and He‐like lines of the heavy elements are emitted, the collisional‐ionization and corona‐condition approximations are justified. We have calculated the line emissivity and ionization profiles for iron as a function of height within the post‐shock flow. For low‐mass white dwarfs, line emission takes place near the shock. For high‐mass white dwarfs, most of the line emission takes place in regions well below the shock and hence it is less sensitive to the shock temperature. Thus, the line ratios are useful to determine the white dwarf masses for the low‐mass white dwarfs, but the method is less reliable when the white dwarfs are massive. Line spectra can, however, be used to map the hydrodynamic structure of the post‐shock accretion flow.