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Discovery of monochromatic oscillations in optical spectrum of the intermediate polar RE 0751+14 *
Received 9 September 1996 / Accepted 26 November 1997
We report the results of optical dynamic spectroscopy and spectropolarimetry of the intermediate polar RE 0751+14 which were obtained with the help of the multichannel photon-counting system (scanner) in a high time resolution mode (32 ms) at the 6 m telescope (BTA) from February 1993 to March 1996. The dependences of the power of oscillations on the wavelengths (3900-5200 Å, 1 Å/channel) and periods of pulsations in the region 300-2000 s with a mean resolution along the period 10 s have been ivestigated. The statistically significant (the probability of random signal is till ) perturbations of spectral composition of the photoelectron noise in the narrow wavelength passbands (1 Å) were discovered. Power spectra have revealed strong (amplitude up to 40%), circularly polarized (dominating in one polarization) monochromatic (FWHM in power spectra 2-3 Å) oscillations with periods of 13.3-15.2 min in the vicinity of the spin period of the white dwarf (13.9 min) mainly in the profiles of emission lines with the time of life 3000-5000 s. The wavelengths of the oscillations correspond to the solutions of the Schrödinger equation in strong resonance magnetic fields (quadratic Zeeman effect). The equation for calculations of resonance magnetic fields for transitions is the equality of the wavelength shifts due to the linear and quadratic terms of the Zeeman effect. As a result of the detection of the oscillations corresponding to transitions, the resonance magnetic fields equal for strongest transitions of 4 MGs and for 9 MGs were measured. The strong magnetic fields indicate that the sources of radiation causing the oscillations are in the accretion column of the white dwarf. On the basis of analysis of properties of the oscillations we conclude that the physical nature of the sources of the oscillations and its radiation cannot be explained in frame of a conventional physics.
Key words: white dwarfs accretion stars: individual: RE 0751+14 stars: oscillations polarization stars: magnetic fields
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© European Southern Observatory (ESO) 1998
Online publication: March 23, 1998