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V405 Aurigae: A High Magnetic Field Intermediate Polar
- Source :
- The Astrophysical Journal. 684:558-568
- Publication Year :
- 2008
- Publisher :
- American Astronomical Society, 2008.
-
Abstract
- Our simultaneous multicolor (UBVRI) circular polarimetry has revealed nearly sinusoidal variation over the WD spin cycle, and almost symmetric positive and negative polarization excursions. Maximum amplitudes are observed in the B and V bands (+-3 %). This is the first time that polarization peaking in the blue has been discovered in an IP, and suggests that V405 Aur is the highest magnetic field IP found so far. The polarized flux spectrum is similar to those found in polars with magnetic fields in the range B ~ 25-50 MG. Our low resolution circular spectropolarimetry has given evidence of transient features which can be fitted by cyclotron harmonics n = 6, 7, and 8, at a field of B = 31.5 +- 0.8 MG, consistent with the broad-band polarized flux spectrum. Timings of the circular polarization zero crossovers put strict upper limits on WD spin period changes and indicate that the WD in V405 Aur is currently accreting closely at the spin equilibrium rate, with very long synchronization timescales, T_s > 10^9 yr. For the observed spin to orbital period ratio, P_{spin}/P_{orb} = 0.0365, and P_{orb} ~ 4.15 hr, existing numerical accretion models predict spin equilibrium condition with B ~ 30 MG if the mass ratio of the binary components is q_1 ~ 0.4. The high magnetic field makes V405 Aur a likely candidate as a progenitor of a polar.<br />To appear in The Astrophysical Journal, September 1 Issue (2008), 9 pages, 10 figures
- Subjects :
- Physics
Astrophysics::High Energy Astrophysical Phenomena
Astrophysics (astro-ph)
FOS: Physical sciences
Astronomy and Astrophysics
Astrophysics
Mass ratio
Polarization (waves)
Orbital period
Magnetic field
Amplitude
Intermediate polar
Space and Planetary Science
Astrophysics::Solar and Stellar Astrophysics
Polar
Circular polarization
Subjects
Details
- ISSN :
- 15384357 and 0004637X
- Volume :
- 684
- Database :
- OpenAIRE
- Journal :
- The Astrophysical Journal
- Accession number :
- edsair.doi.dedup.....e53e7b5420b2fd0d56276bef1308e32b
- Full Text :
- https://doi.org/10.1086/590144