Article

Whole Earth Telescope observations of V471 Tauri - The nature of the white dwarf variations

07/1992;
Source: NTRS

ABSTRACT Time-series photometric observations of the binary star V471 Tauri were conducted using the Whole Earth Telescope observing network. The purpose was to determine the mechanism responsible for causing the 555 and 277 s periodic luminosity variations exhibited by the white dwarf in this binary. Previous observers have proposed that either g-mode pulsations or rotation of an accreting magnetic white dwarf could cause the variations, but were unable to decide which was the correct model. The present observations have answered this question. Learning the cause of the white dwarf variations has been possible because of the discovery of a periodic signal at 562 s in the Johnson U-band flux of the binary. By identifying this signal as reprocessed radiation and using its phase to infer the phase of the shorter wavelength radiation which produces it, made it possible to compare the phase of the 555 s U-band variations to the phase of the X-ray variations. It was found that U-band maximum coincides with X-ray minimum. From this result it was concluded that the magnetic rotator model accurately describes the variations observed, but that models involving g-mode pulsations do not.

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Keywords

277 s periodic luminosity variations exhibited
 
555 s U-band variations
 
accreting magnetic white
 
binary star V471 Tauri
 
g-mode pulsations
 
Johnson U-band flux
 
magnetic rotator model
 
mechanism responsible
 
periodic signal
 
possible
 
present observations
 
Previous observers
 
reprocessed radiation
 
shorter wavelength radiation
 
Time-series photometric observations
 
U-band maximum coincides
 
unable
 
Whole Earth Telescope
 
X-ray minimum
 
X-ray variations
 

J.C. Clemens