Accession Number : ADA327573

Title :   A Modified Beat Frequency Modulated Accretion Model I. Spin Periods and Magnetic Moments of Z-Sources Inferred from Horizontal Branch QPO.

Descriptive Note : Technical rept.,

Corporate Author : STANFORD UNIV CA W W HANSEN LABS OF PHYSICS

Personal Author(s) : Wood, Kent S. ; Michelson, Peter F. ; Roberts, Mallory S.

PDF Url : ADA327573

Report Date : 1996

Pagination or Media Count : 35

Abstract : We present a modified beat-frequency modulated accretion model appropriate to a description of the horizontal branch oscillations of Z-type low-mass x-ray binaries. This model incorporates several new physical elements: (1) magnetic screening by the accretion disk and neutron star, (2) radiation pressure dominance in the inner disk, and (3) stellar rotation effects. Fitted to observational data, the model constrains the surface magnetic field in a typical LMXB Z source to be less than 10(exp 9) G and the stellar spin frequency to be greater than 400 Hz. The predicted high stellar spin frequency falls in a range where observational upper limits on pulsation are not a constraint. The derived magnetic field and spin frequency range are compatible with the fastest radio pulsars.

Descriptors :   *BINARY STARS, *NEUTRON STARS, MAGNETIC FIELDS, FREQUENCY MODULATION, PLASMA OSCILLATION, RADIATION PRESSURE, MAGNETIC MOMENTS, RADIO SOURCES(ASTRONOMY), X RAY ASTRONOMY, STELLAR EVOLUTION, PULSARS.

Subject Categories : Astronomy
      Astrophysics

Distribution Statement : APPROVED FOR PUBLIC RELEASE