AAS 201st Meeting, January, 2003
Session 33. Stars Dead or Alive
Oral, Monday, January 6, 2003, 2:00-3:30pm, 606-607

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[33.06] Radio and X-ray Emission Properties of Magnetic Chemically Peculiar Stars

S.A. Drake (USRA & NASA/GSFC), J.L. Linsky (U. Colorado), G.A. Wade (RMC, Canada)

Magnetic Chemically Peculiar (MCP) stars have been known since the mid 1980's to be radio emitters, with high radio luminosities, moderate circular polarization, and fairly flat microwave spectra, which are similar to the radio properties of active cool stars such as RS CVns. The radio emission mechanism in both cases is believed to be gyrosynchrotron emission from mildly relativistic nonthermal electrons. By 2002, about 120 MCP stars have been observed in the radio, and 25% detected as radio emitters. Radio sources have been found among all types of MCP stars except the subclass of A-type SrCrEu-type stars. The radio luminosities of MCP stars are correlated with increasing effective temperature and magnetic field strength, and (with less confidence) with decreasing rotational period.

The status of MCP star X-ray emission is much less clear. Although many MCP stars have been associated with X-ray sources in the last two decades, there is still uncertainty as to whether X-ray emission is an intrinsic property of this class, since is not obviously correlated with any of the other stellar and/or radio properties. In many cases, the X-ray emission may, in fact, be due to a lower-mass stellar companion rather than to the MCP star. This lack of correlation with the radio properties is in stark contrast with active late-type stars where the X-ray and radio emission levels are well-correlated. We discuss the implications of the observed radio and X-ray properties of MCP stars on the various models proposed to explain the high-energy emission from these stars, such as the magnetospheric and the magnetically confined wind shock models, and suggest some observational tests which may help to constrain or refine them.

The author(s) of this abstract have provided an email address for comments about the abstract: Steve.Drake@gsfc.nasa.gov

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.