Youngest` neutron-star binary found

Washington – X-rays streaming towards Earth from the region near a neutron star that is cannibalizing its companion star are the youngest “X-ray binary” yet known, according to scientists.

The team discovered the age of this record-breaking pair, named Circinus X-1, by using data from NASA’s Chandra X-ray Observatory, which revealed faint remnants of the supernova explosion that created the neutron star.

Niel Brandt, Distinguished Professor of Astronomy and Astrophysics, said that he was perplexed by the unusually strong evolution of the orbit of Circinus X-1 since my graduate-school days, asserting that the discovery now of this system’s youth provides a satisfying explanation for why its orbit evolves so strongly – as the system likely still is settling down after its violent birth.

The research team, which was led by Sebastian Heinz at the University of Wisconsin-Madison, determined that Circinus X-1 is less than 4,600 years old.

Heinz asserted that X-ray binaries provide us with opportunities to study matter under extreme conditions that would be impossible to recreate in a laboratory, saying that for the first time, they can study a newly minted neutron star in an X-ray binary system.

X-ray binaries are star systems made up of two parts: a compact stellar remnant — either a neutron star or a black hole — and a companion star, a normal star like our Sun.

To determine the age of Circinus X-1, the astronomers recently caught a break, when they observed the neutron star in a very faint state — dim enough for scientists to detect the X-rays from the supernova shock wave that plowed through the surrounding interstellar gas.

The discovery has been published in The Astrophysical Journal.