Spectacular star system discovered which could explode to create powerful cosmic firework display

Collision between winds of two stars has formed elegant spiral dust cloud as the stars orbit each other

Spectacular star system wrapped in elegant spiral dust cloud
The newly discovered binary star system. Credit: ESO/Callingham et al.

A spectacular star system wrapped in an elegant spiral dust cloud has been discovered by astronomers. The system is believed to contain a star that is spinning extremely fast, which could produce one of the most powerful explosions in the Universe.

The binary star system, containing a pair of massive ‘Wolf-Rayet’ stars, has been discovered by an international team of researchers, including Professor Paul Crowther from the University of Sheffield, and published in Nature Astronomy.

Wolf-Rayet stars are amongst the hottest stars in the Universe, blast out powerful winds of hot gas, and represent the last stage in the evolution of the most massive stars prior to exploding as a supernova.

Located around 8,000 light years away – half a billion times further away than our Sun – the binary system is surrounded by a gigantic dust cloud. The collision between the winds of the two stars can form dust, which takes on elegant spiral pinwheel shapes as the stars orbit each other.

Using the Very Large Telescope (VLT) in Chile and the Anglo-Australian Telescope (AAT) in Australia, the team has found that the star system is producing incredibly fast winds, 100,000 times quicker than a hurricane on Earth. This wind speed is routine for Wolf-Rayet stars. However, the researchers discovered that the dust cloud is moving much slower.

The differing speeds of wind and dust suggest that the Wolf-Rayet stars are spewing out faster gas at the poles and slower gas at the equator, according to the study, which was led by Dr Joseph Callingham from the Netherlands Institute for Radio Astronomy.

Co-author Dr Benjamin Pope from New York University commented: "One way for such different winds to happen is via critical rotation."

Critical rotation is needed in most supernova models for a star’s fiery death to be accompanied by the most energetic explosion in the Universe: a gamma-ray burst.

Professor Paul Crowther from the University of Sheffield’s Department of Physics and Astronomy, said: "It remains a mystery how dust – similar to soot from a candle – forms in such harsh environments, but this newly discovered system is the most beautiful case seen to date."

The system has been nicknamed Apep, after an ancient Egyptian deity

The study was conducted by Dr Joseph Callingham from the Netherlands Institute for Radio Astronomy (ASTRON), Professor Peter Tuthill from the University of Sydney, Dr Benjamin Pope, NASA Sagan Fellow at New York University, Dr P. Williams from the University of Edinburgh, Professor Paul Crowther from the University of Sheffield, Mr. M. Edwards from the University of Sydney, Dr B. Norris from the University of Sydney and Dr L. Kedziora-Chudczer from the University of New South Wales.

Read the paper

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