The most-distant, super-luminous supernovae found to date have been observed by an international team, including Raymond Carlberg of the University of Toronto's Department of Astronomy & Astrophysics. The stellar explosions would have occurred at a time when the universe was much younger and probably soon after the Big Bang.
"The objects are both unusually bright and unusually slow to fade. These are properties that are consistent with what is known as pair-instability supernova, a rare mechanism for explosion which is expected to happen for high-mass stars with almost no metal content. That is, the very first stars to form," said Carlberg.
The two supernovae, identified as SN2213 and SN1000+2016, were discovered in image data obtained via the Canada-France-Hawaii Telescope Legacy Survey. In recent years, various surveys have enabled astronomers to open new windows on the universe, including the discovery over the past decade of super-luminous supernovae that are tens to hundreds of times more luminous than regular supernovae. "The Canada-France-Hawaii Telescope Legacy Survey stands out as the first really deep survey of the sky, covering large volumes of the universe," said Carlberg, a Canadian leader of the Survey.
All of the processing of the image data was done at U of T using a search technique that first vastly narrows the search to the high redshift star-forming galaxies and then looks for supernovae that are more luminous than normal supernovae and have unusually long fading times — precisely the characteristics of pair-instability supernovae.
The pair-instability explosion mechanism only occurs in stars that are about 150-300 times more massive than the sun, explains Carlberg. No stars that massive form in the current universe because as stars are assembled they start nuclear burning and push away additional gas. However, in the very early days of the universe, the metal abundance of the gas is essentially zero, making it almost transparent so that it can fall on the forming star.
Such massive stars do not last long. They are so hot in the centre that pressure is lost causing a collapse to start, which then heats up the core even more. Eventually enough oxygen and silicon are created that their fusion causes a nuclear explosion much more luminous than other supernova mechanisms.
"Super-luminous Supernova Discoveries at z=2.05 and z=3.90," is published online in Nature at http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11521.html and will appear in the November 8 print edition
University of Toronto: http://www.utoronto.ca
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
After landing a probe on an icy comet, the European Space Agency (ESA) is now heading to scorching-hot Mercury with its BepiColombo spacecraft.
To see back in time, you need a massive telescope—one big enough to capture light from when the first galaxies were formed, 13.5 billion years ago. Astronomers are clamoring to see this light, so NASA is obliging them by building the James Webb Space Telescope.
No one knows what the planet Gliese 667Cc looks like. We know that it is about 22 light-years from Earth, a journey of lifetimes upon lifetimes. But no one can say whether it is a world like ours, with oceans and life, cities and single-malt Scotch. Only a hint of a to-and-fro oscillation in the star it orbits, detectable by Earth's most sensitive telescopes and spectrographs, lets astronomers say the planet exists at all.
A top U.S. Air Force official on Wednesday said she is "pretty optimistic" that privately held Space Exploration Technologies will eventually be certified to launch U.S. military satellites into orbit but declined comment on the timing of such an action.
A dramatic study—and an equally dramatic video simulation—reveal a cataclysmic cosmic event
Dan Winters There’s no way to anticipate the emotional impact of leaving your home planet. You look down at Earth and realize: You’re not on it. It’s breathtaking. It’s surreal. It’s a “we’re not in Kansas anymore, Toto” kind of feeling.
A Russian spacecraft is visiting satellites, raising fears it could be part of an anti-satellite programme – if it's not an inspection craft
The European Space Agency has announced that Philae has detected organic molecules on comet 67P – and there are many more scientific discoveries to come
European comet lander Philae 'sniffed' organic molecules containing the carbon element that is the basis of life on Earth before its primary battery ran out and it shut down, German scientists said.
Boeing Co is working with the U.S. Missile Defense Agency to address quality and reliability issues with the sharply criticized $41 billion homeland missile defense system by adopting controls from space programs, a company official said.