Tychos supernova remnant: New evidence on origin of supernovas found

Astronomers may now know the cause of an historic supernova explosion that is an important type of object for investigating dark energy in the universe. The discovery, made using NASAs Chandra X-ray Observatory, also provides strong evidence that a star can survive the explosive impact generated when a companion star goes supernova.

The new study examined the remnant of a supernova observed by the Danish astronomer Tycho Brahe in 1572. The object, dubbed Tycho for short, was formed by a Type Ia supernova, a category of stellar explosion useful in measuring astronomical distances because of their reliable brightness. Type Ia supernovas have been used to determine that the universe is expanding at an accelerating rate, an effect attributed to the prevalence of an invisible, repulsive force throughout space called dark energy.

A team of researchers analyzed a deep Chandra observation of Tycho and found an arc of X-ray emission in the supernova remnant. Evidence supports the conclusion that a shock wave created the arc when a white dwarf exploded and blew material off the surface of a nearby companion star.

“There has been a long-standing question about what causes Type Ia supernovas,” said Fangjun Lu of the Institute of High Energy Physics, Chinese Academy of Sciences in Beijing. “Because they are used as steady beacons of light across vast distances, it is critical to understand what triggers them.”

This is an artist's impression showing an explanation from scientists for the origin of an X-ray arc in Tycho's supernova remnant. It is believed that material was stripped off the companion star by the explosion of the white dwarf in the Type Ia supernova explosion, forming the shock wave seen in the arc. The arc has blocked debris from the explosion, creating a "shadow" behind the arc. The force of the explosion imparted a kick to the companion star, and this combined with the orbital velocity of the companion before the explosion to give the "observed" motion of the companion. Previously, studies with optical telescopes have revealed a star within the remnant that is moving much more quickly than its neighbors, showing that it could be the companion to the supernova. The size of the companion's orbit is not shown to scale here: the separation between it and the white dwarf before the explosion is estimated to have only been about a millionth of a light year, while the full scale of the illustration is over 10 light years.

via Tychos supernova remnant: New evidence on origin of supernovas found.

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