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A radio-pulsing white dwarf binary star
T R Marsh1, B T Gänsicke1, S Hümmerich2,3
1Department of Physics, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL, UK.
Nature
|July 28, 2016
Summary
We discovered AR Scorpii, a unique white dwarf binary system emitting across the electromagnetic spectrum. This magnetic white dwarf
Area of Science:
- * Astronomy and Astrophysics
- * Compact Stars
- * Binary Systems
Background:
- * White dwarfs are Earth-sized, dense stellar remnants.
- * Typically emit UV to near-IR radiation.
- * In binaries, mass transfer can cause X-ray and IR emission, but far-IR/radio detection is rare.
Purpose of the Study:
- * To report the discovery of a white dwarf/cool star binary emitting from X-ray to radio wavelengths.
- * To characterize the unusual emission properties of the AR Scorpii system.
Main Methods:
- * Multi-wavelength observations (X-ray to radio).
- * Analysis of light curves and spectral properties.
- * Determination of orbital and spin periods.
Main Results:
- * Discovery of AR Scorpii, a 3.56-hour period binary system.
- * Intense, rapid pulsations (1.97 min period) detected across optical and radio frequencies.
- * White dwarf spin-down power significantly exceeds electromagnetic output, indicating spin-power dominance.
- * Broadband spectrum consistent with synchrotron radiation, requiring relativistic electrons.
Conclusions:
- * AR Scorpii is a primarily spin-powered magnetic white dwarf binary.
- * Pulsations, driven by white dwarf spin, originate mainly from the cool companion star.
- * Relativistic electrons are crucial for the observed synchrotron emission, likely generated near the white dwarf or at the M star.
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