Astronomers have identified AR Scorpii a binary stellar system in the constellation Scorpius, 380 light-years from Earth as the first example of a white dwarf pulsar.

AR Scorpii, the first discovered white dwarf pulsar. In this unique double star a rapidly spinning white dwarf (right) powers electrons up to almost the speed of light. These high energy particles release blasts of radiation that lash the companion red dwarf (left) and cause the entire system to pulse dramatically every 1.97 minutes with radiation ranging from UV to radio. Image credit: M. Garlick / University of Warwick / ESO.

AR Scorpii is composed of a cool, low-mass star in a tight, 3.55-hour orbit with a more massive white dwarf.

The distance between the two stars is around 1.4 million km which is three times the distance between the Moon and the Earth.

The low-mass companion in AR Scorpii a red dwarf star is about one-third the mass of the Sun. The white dwarf is the size of Earth but 200,000 times more massive.

This system was recently discovered to pulse in brightness every 1.97 min from UV wavelengths into the radio regime.

AR Scorpiis white dwarf lashes its red dwarf companion with powerful beams of electrical particles and radiation.

According to new research in the journal Nature Astronomy, the lash of energy is a focused beam, emitting concentrated radiation in a single direction much like a particle accelerator something which is totally unique in the known Universe.

The new data show that AR Scorpiis light is highly polarized, showing that the magnetic field controls the emission of the entire system, and a dead ringer for similar behavior seen from the more traditional neutron star pulsars, said co-author Prof. Tom Marsh, from the University of Warwick, UK.

With an electromagnetic field 100 million times more powerful than Earth, AR Scorpii produces lighthouse-like beams of radiation and particles, which lash across the face of the red dwarf.

AR Scorpii is like a gigantic dynamo: a magnet, size of the Earth, with a field that is roughly 10,000 stronger than any field we can produce in a lab, and it is rotating every two minutes, said co-author Prof. Boris Gnsicke, also from the University of Warwick.

This generates an enormous electric current in the companion star, which then produces the variations in the light we detect.

_____

D. A. H. Buckley et al. 2017. Polarimetric evidence of a white dwarf pulsar in the binary system AR Scorpii. Nature Astronomy 1, article number: 0029; doi: 10.1038/s41550-016-0029

The rest is here:

Astronomers Find First Ever White Dwarf Pulsar - Sci-News.com