white dwarf star pulsar

Discovered: Elusive White Dwarf Pulsar Lashes Partner Red Dwarf With Energy Whip

Astronomers have known that white dwarf pulsars have existed for at least a half-century, but it wasn’t until recently that scientists actually discovered a true white dwarf pulsar, pushing the theoretical into the actual. And the white dwarf pulsar exists in a binary star system with a red dwarf, making the discovery a bit more exotic in that the pulsar lashes out with its electromagnetic radiation beam and hits the red dwarf a couple times every two minutes.

Phys.org reported last week that professors Tom Marsh and Boris Gänsicke from the University of Warwick’s Astrophysics Group, along with Dr. David Buckley from the South African Astronomical Observatory, discovered a white dwarf pulsar just a mere 380 light years away. That star, designated AR Scorpii (or AR Sco) by astronomers, is the first of its kind ever discovered.

Scientists found out about the existence of pulsars (highly magnetized neutron stars or white dwarfs) in the 1960s and although white dwarf pulsars were thought to exist, they did so only in theory. Oddly enough, the star AR Sco itself was discovered four decades ago, but its uniqueness would remain a secret those 40 years.

Lead researcher Tom Marsh said (per a separate Phys.org report), “AR Sco was discovered over 40 years ago, but its true nature was unsuspected until we observed it last May with a high-speed astronomical camera called ULTRACAM on the William Herschel Telescope. We realized we were seeing something extraordinary within minutes of starting to observe it.”

Professor Boris Gansicke agreed, saying, “It’s very exciting that we have discovered such a system, and it has been a fantastic example of amateur astronomers and academics working together.”

AR Sco is quick-spinning, burned out stellar remnant that lashes its neighbor – a red dwarf about a third the size of our Sun – with powerful electromagnetic beams, which causes the entire binary system to brighten and fade in a sort of lighthouse effect twice every two minutes. The electromagnetic beam itself is focused, which means that the beam is directed in a concentrated manner in one direction. It is unique in all the known universe.

white dwarf and red dwarf binary
Astronomers believe that there are more binary star systems than any other configuration in the universe. [Image by Catmando/Shutterstock]

AR Sco can be found in the constellation Scorpius. The white dwarf is roughly the size of the Earth. However, it is 200,000 times more massive. It spins around its neighboring red dwarf, which is a mere 1.4 million kilometers (870,000 miles) away, every 3.6 hours. The beam emitted from AR Sco fires into the red dwarf and accelerates the electrons in its atmosphere to nearly the speed of light, basically charging up the smaller star. The process has never been witnessed before in binary star relationships.

Professor Gänsicke said of the discovery, “AR Sco is like a gigantic dynamo: a magnet, size of the Earth, with a field that is ~10.000 stronger than any field we can produce in a laboratory, and it is rotating every two minutes. This generates an enormous electric current in the companion star, which then produces the variations in the light we detect.”

A white dwarf star and incoming objects
Until this recent find, white dwarf stars were only theorized to act as pulsars. [Image by muratart/Shutterstock]

In other white dwarf-related astronomy news, a white dwarf was also recently observed, using NASA’s Hubble Space Telescope, shredding apart an enormous object with a composition much like a comet. According to redOrbit, researchers found an enormous comet-like object comparable to the make-up of Halley’s Comet (but is 100,000 times larger and carries a greater quantity of water) was detected being torn apart by its white dwarf parent star. That astronomical first came with a bonus: It was determined that the comet-like object was rich in the elements necessary for life, including carbon, oxygen, and nitrogen.

The observations are evidence that suggests the existence of a belt of comet-like objects in orbit around the white dwarf, a collection comparable to the Solar System’s Kuiper Belt, which moves in the outer reaches of our solar system past the orbit of Neptune.

[Featured Image by Jurik Peter/Shutterstock]