Astronomers’ sky survey spots most distant supernova ever seen

An international team of astronomers has discovered the most distant supernova ever seen. Light from the stellar blast has taken 10.5 billion years to reach us.

The Dark Energy Camera (DECam) mounted on the 4-metre Blanco Telescope , Image credit: Reidar Hahn, Fermilab

The catastrophic explosion happened when the Universe was only a quarter of its current age of 13.8 billion years. It was spotted in images taken by a 570-megapixel digital camera mounted on the 4-metre Blanco Telescope at Cerro Tololo Inter-American Observatory, on a peak in the Chilean Andes.

The camera, called DECam, is part of an international project to study a mysterious dark force in the Universe that is thought to be causing it to expand. It is known as the Dark Energy Survey, and works by mapping 300 million galaxies far beyond our own Milky Way.

The star that blew itself to bits is labelled DES16C2nm and is one of a specially bright and unusual type called a superluminous supernova, or SLSN. Such a supernova can become brighter than all the other stars in a galaxy combined.

SLSNs, the brightest and rarest class of supernovae, were first identified 10 years ago. They are thought to be caused by material falling onto the densest object in the Universe, a rapidly rotating neutron star newly formed in the explosion of a massive star.

Annotated images of the patch of sky photographed by DECam before and after the supernova blast.

Lead scientist in the discovery, Dr Mathew Smith, of the University of Southampton, said: “It’s thrilling to be part of the survey that has discovered the oldest known supernova.

“DES16C2nm is extremely distant, extremely bright, and extremely rare – not the sort of thing you stumble across every day as an astronomer.”

Smith said the ultraviolet light from these supernovae “informs us of the amount of metal produced in the explosion and the temperature of the explosion itself, both of which are key to understanding what causes and drives these cosmic explosions.”

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Related: Weird supernova breaks all the rules with multiple blasts

More than 400 scientists from around the world are involved in the Dark Energy Survey, which began in 2013 and is collecting data on galaxies which lie billions of light-years away from Earth.

Chris D’Andrea, a postdoctoral fellow at the University of Pennsylvania, commented: “What we think could be happening here is that the stellar explosion produces a magnetar at its core – a rapidly spinning neutron star with a magnetic field 100 trillion times stronger than that on Earth.

“If we look at how the light from the superluminous supernova evolves in time, it matches very well models of the amount of energy that magnetars emit as they spin. This energy is hitting the winds of the ejected material from the stellar explosion and dramatically brightening what we’re seeing.”

Colleague Masao Sako, an associate professor in the University of Pennsylvania’s School of Arts and Sciences, said that such supernovae could lead to advances in both stellar astrophysics and cosmology. By investigating why and how stars die, scientists could learn more about how compact objects such as black holes and neutron stars are created.

The find comes soon after the announcement of the discovery of the furthest known black hole in the Universe.

Related: Cosmic CSI squad name supernova star


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