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Radiation-Driven Acceleration in Photospheres of Nonaccreting Magnetic White Dwarfs

Published online by Cambridge University Press:  12 April 2016

Vladimir V. Zheleznyakov  and
A. V. Serber
Vladimir V. Zheleznyakov
Affiliation:
Institute of Applied Physics, Russian Academy of Science, ul. Ul’yanova 46, 603600 Nizhny Novgorod, Russia
A. V. Serber
Affiliation:
Institute of Applied Physics, Russian Academy of Science, ul. Ul’yanova 46, 603600 Nizhny Novgorod, Russia

Abstract

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Radiation transfer in a pure hydrogen, fully ionized, isothermal photosphere of an isolated white dwarf with dipole magnetic field is considered, and the radiation pressure force, both in the continuum and in the cyclotron line, is determined with the line saturation effect taken into account. It is shown that the magnetic field can reduce the critical luminosity for white dwarfs. This leads to the possibility of photospheric plasma ejection driven by the radiation in the cyclotron line and the formation of radiation-driven winds from sufficiently hot isolated magnetic white dwarfs.

It is shown that cyclotron radiation pressure plays a significant role in the force balance of the photospheres of the magnetic white dwarfs GD 229, GrW +70° 8247, and PG 1031+234. The strong unidentified depression in the UV spectrum of GD 229 is attributed to cyclotron scattering by the radiation-driven plasma envelope with density N ≳ 108 cm−3 .

Subject headings: radiative transfer — stars: atmospheres — stars: magnetic fields — white dwarfs

Type
Stars
Information
International Astronomical Union Colloquium , Volume 142: Particle Acceleration Phenomena in Astrophysical Plasmas , 1994 , pp. 783 - 787
Copyright
Copyright © The American Astronomical Society 1994

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