Astronomers have discovered a new type of exotic binary star system, in which a rapidly spinning white dwarf star is lashing the companion red dwarf star with high-energy particles, causing the entire system to pulse dramatically every 1.97 minutes with radiation ranging from the ultraviolet to radio.
The binary system was discovered by a group of amateur astronomers from Germany, Belgium and Britain. Its behaviour was unlike anything they had ever encountered before.
The true nature of this previously misidentified system was then observed by researchers at the University of Warwick using a multitude of telescopes on the ground and in space, including the NASA/ESA Hubble Space Telescope.
The star system AR Scorpii (AR Sco) lies in the constellation of Scorpius, 380 light years from Earth.
“AR Scorpii was discovered over 40 years ago, but its true nature was not suspected until we started observing it in June 2015. We realised we were seeing something extraordinary the more we progressed with our observations,” said lead researcher Tom Marsh from the University of Warwick.
The radiation across a broad range of frequencies is indicative of emission from electrons accelerated in magnetic fields, which can be explained by AR Sco’s spinning white dwarf.
The source of the electrons themselves, however, is a major mystery — it is not clear whether it is associated with the white dwarf or its cooler companion, said the study published in the journal Nature.
“We’ve known about pulsing neutron stars for nearly 50 years and some theories predicted white dwarfs could show similar behaviour. 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,” said study co-author Boris Gansicke.