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Supernova leftovers point to a messy blowup

White dwarf and red giant
This artist’s view shows a white dwarf star accumulating material from a nearby red giant star. Ultimately, the white dwarf erupts into a supernova. (Instituto de Astrofísica de Canaria Illustration / Romano Corradi)

In what sounds like a cosmic episode of “CSI,” sleuthing astronomers have figured out what touched off a stellar explosion 545 million light-years away, based on evidence left behind at the scene of the crime.

An international team of astronomers used the Hubble Space Telescope and other observatories to sift through the chemical fingerprints left behind in the remnants of a Type Ia supernova known as SN 2015cp. The astronomers knew the type of star that blew up: It was a carbon-oxygen white dwarf. But they wanted to find out whether a different kind of star had a hand in the blast.

Today the astronomers reported the detection of hydrogen-rich debris in the vicinity of the supernova site — which cracks the case wide open.

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Number crunchers are on the trail of dark energy

Saul Perlmutter
Berkeley astrophysicist Saul Perlmutter discusses the implications of the universe’s accelerating expansion at the University of Washington. (GeekWire Photo / Alan Boyle)

Big data just might give astronomers a better grip on the answer to one of the biggest questions in physics: Exactly what’s behind the mysterious acceleration in the expansion rate of the universe, also known as dark energy?

And that means the number crunchers at the University of Washington’s DIRAC Institute have their work cut out for them.

The role of data analysis in resolving the mystery came to the fore on May 14 during a talk given at the DIRAC Institute’s first-ever open house on the UW campus. The speaker was none other than Berkeley astrophysicist Saul Perlmutter, who won a share of the Nobel Prize in physics in 2011 for finding the first evidence of dark energy.

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Supernovae spread radioactive fallout on Earth

Image: Supernova
An artist’s impression shows a supernova explosion in its prime. (Credit: Greg Stewart / SLAC)

Researchers say they’ve found evidence of supernova explosions that spewed radioactive fallout over Earth during the age when humanity’s ancestors were evolving into upright-walking, big-brained creatures.

One of two studies published in the journal Nature identifies deposits of radioactive iron-60 in deep-sea cores extracted from the bottom of the Indian, Pacific and Atlantic oceans. The deposits were traced back to one time frame ranging from 1.5 million to 3.2 million years ago, and another period 6.5 million to 8.7 million years ago.

The researchers behind that study, led by Anton Wallner of Australian National University, say the iron-60 was blasted toward us by “multiple supernova and massive-star events” that occurred within 325 light-years of Earth.

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Hubble catches supernova’s ‘instant replay’

Image: Hubble supernova
The red circles on this image from the Hubble Space Telescope indicate the three spots where flashes from Supernova Refsdal showed up at different times. The middle circle indicates the spot where it was last observed on Dec. 11. (Credit: NASA / ESA / GLASS / Frontier Fields / CLASH)

Astronomers traced one of the weirder twists in relativity to determine when they’d see an “instant replay” of a distant supernova, and now the Hubble Space Telescope has shown that their prediction was right. They say it marks the first time a supernova observation was predicted in advance.

The confirmation comes in the form of Hubble’s observations of the galaxy cluster MACS J1149.5+2223 over the course of more than a year. When scientists studied pictures taken in November 2014, they identified a supernova flash that had beensplit into four separate images, due to the cluster’s gravitational lensing effect.

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