South Africa's New Radio Telescope SKA Reveals Giant Outbursts from Binary Star System

An artist's impression of the Circinus X-1 system showing the binary (double) star system. 

Two stars orbit each other every 16.5 days in an elliptical orbit. 

The small white sphere is the neutron star - an extremely dense and compact remnant of an exploded star, only about 20 km in diameter. 

The red sphere is an ordinary star - the companion star in this system. 

When the two stars are at their closest, the neutron star pulls material from its companion star. 

An accretion disk (the blue disk) forms around the neutron star, containing the matter that is sucked from the ordinary star. 

Powerful jets of material (the orange rays) then blast out from the neutron star at close to the speed of light, causing powerful flares in radio frequencies. 

Credit: Image courtesy of University of Southampton /SKA South Africa

An international team of astronomers have reported the first scientific results from the Karoo Array Telescope (KAT-7) in South Africa, the pathfinder radio telescope for the $3 billion global Square Kilometre Array (SKA) project.

The results appear in the latest issue of the international astronomical journal Monthly Notices of the Royal Astronomical Society (MNRAS).

Using the seven-dish KAT-7 telescope and the 26 m radio telescope at the Hartebeesthoek Radio Astronomy Observatory (HartRAO), astronomers have observed a neutron star system known as Circinus X-1 as it fires energetic matter from its core into the surrounding system in extensive, compact `jets' that flare brightly, details of which are visible only in radio waves.

Journal Reference: 
R. P. Armstrong, R.P. Fender, G.D. Nicolson, S. Ratcliffe, M. Linares, J.Horrell, L. Richter, M. P. E. Schurch, M. Coriat, P. Woudt, J. Jonas, R. Booth, B. Fanaroff. A return to strong radio flaring by Circinus X-1 observed with the Karoo Array Telescope test array KAT-7. Monthly Notices of the Royal Astronomical Society, 2013