The supernova was first detected in 2001 by Franz Bauer of Columbia University who noticed a bright object in the spiral galaxy Circinus using NASA’s Chandra X-ray Observatory.  At the time, however, Bauer and his colleagues could not confidently indentify its nature.

Not until they mined the vast online public archives containing data from many of the 18 different telescopes in space and on the ground, could Bauer and his team confirm what they had discovered:  One of the nearest supernovas in the last 25 years that had exploded a decade earlier.

Its discovery is leading researchers to claim that we have entered a new era of “Internet astronomy.”

The supernova, dubbed SN 1996cr, exploded between February 28, 1995 and March 15, 1996. It is among the brightest supernovas ever seen in radio and X-rays.  It also bears many striking similarities to the famous supernova SN 1987A, which occurred in a galaxy only 160,000 light years from Earth. 

Bauer, principal investigator of the project, enlisted York astronomers Norbert Bartel and Michael Bietenholz to provide a clearer picture of the supernova using their expertise in VLBI (Very Long Baseline Interferometry). VLBI is the simultaneous use of several networked telescopes to detect radio waves and make a very sharp image of a celestial object.

“This supernova is proving to be the strongest radio wave emitter of any supernova we’ve discovered so far, which helps us determine how large the supernova is now, after it has expanded for 10 years,” said Bartel, distinguished research professor in the Department of Physics and Astronomy in York’s Faculty of Science and Engineering.

“It is now 500 times larger than our solar system, and likely also that much larger than any planetary system that may have existed around the star before it exploded. Light now needs seven months to travel from one side of the gigantic shock wave to the other side.”

A supernova is the death of a star, one of the most powerful single events in the universe.  When a star explodes, it ejects its mass into space at a velocity of 20,000 km/sec., freeing most of the heavy elements, such as carbon, iron and oxygen, needed to form planets and sustain life in the universe.

Shortly before SN 1996cr exploded, it shed material from its surface into space at a high velocity, creating a vacuum around it before it died, Bartel said.  Now, several years after the explosion, that material is being hit by the supernova shock wave, causing the system to glow brightly at X-ray and radio wavelengths.

“We are working to interpret what is presently going on when the shock wave hits the surrounding material that was shed from the surface of the star,” Bartel said.

Astronomers think that both SN 1987A and SN 1996cr show evidence of these pre-explosion clear-outs by the star doomed to explode.  Having two nearby examples suggests that this type of activity could be relatively common during the death of massive stars.

SN 1996cr, at a distance of about 12 million light years, will be a compelling target for future work because it is nearby and so much brighter than a typical supernova.

The results of the study, Supernova 1996cr: SN 1987A’s Wild Cousin?, will appear in an upcoming issue of The Astrophysical Journal.  It is now available online. 

Franz Bauer (Columbia University) is lead author of the study.  The co-authors, apart from Bartel and Bietenholz, are Vikram Dwarkadas (University of Chicago),  Niel Brandt (Penn State), Stefan Immler (NASA Goddard Space Flight Center) and Stephen Smartt (Queen's University Belfast).

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Media contact:

Killeen Kelly, Media Relations, York University, 416 736 2100 x22938 / killeenk@yorku.ca