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M82 Supernova

Observations of supernovae (exploding stars) in distant galaxies have transformed our view of the Universe. They help us address the REALLY BIG questions, like: what is everything made of? or what will be the fate of the Universe? Because the information they provide is so critical to answering these big questions searching for them has become big business. There are hundreds of astronomers and dozens of telescopes all over the world engaged in the search for these exploding stars. To unravel the history of the Universe we need to discover lots of them at all different distances, and we need to discover them early - hopefully well before their peak brightness. To do that, astronomers have designed automated searches that regularly scan the skies, harvesting supernova discoveries. There are many such surveys with names that have words in them like, “automated,” “rapid,” and “factory”. In 2011 three astronomers Brian Schmidt, Adam Reiss, and Saul Perlmutter were awarded the Nobel Prize in Physics, "....for the discovery of the accelerating expansion of the Universe through observations of distant supernovae". Searching for supernovae is Big Science with a capital B.

All of this makes what I’m about to tell you even more remarkable. Earlier this week some undergraduate students (at University College London), as part of what w as meant to be a 10 minute telescope workshop, made an extremely important discovery of a supernova in the nearby (extragalactic astronomers consider 12 million light years to be nearby) galaxy M82. Clouds, as they often do in astronomy, played an important role. Poor weather turned the lab into a demonstration of imaging with one of the University’s telescopes. The galaxy M82 was chosen as a target simply because it happened to be located in one of the remaining patches of clear skies. When the image was viewed the professor noticed an extra “star” on the image of M82 - that star was later confirmed to be a supernova. Read more about the amazing story of this serendipitous discovery! 

Later that day observations from Apache Point Observatory in New Mexico identified it as a Type Ia supernova, the same kind of supernova so useful in determining the history of the Universe. Not only that, but they estimate that it was detected a full two weeks before maximum brightness, much earlier than the supernovae are typically detected. And its location in M82 makes it closer than any other supernova of this type ever observed. Since it is so bright and since we’ve captured it so earlier we’ll be able to confirm and refine computer simulations of these exploding stars hopefully solidifying the lynchpin observations that reveal the history and future of our entire Universe. 

The so called double degenerate scenario: two orbiting white dwarf stars inspiral and merge triggering the supernova detonation. Simulation from Pablo Loren-Aguilar and Enrique Garcia-Berro. Visualization by Mark SubbaRao.

The so called double degenerate scenario: two orbiting white dwarf stars inspiral and merge triggering the supernova detonation. Simulation from Pablo Loren-Aguilar and Enrique Garcia-Berro. Visualization by Mark SubbaRao.

So why was the M82 Supernova (now known as SN2014J) discovered by students and not by the big science automated surveys? It turns out that it was too close and too bright. These surveys are tuned to find supernovae in faint distant galaxies, nearby, big, bright galaxies like M82 overexpose.  I find all of this incredibly inspiring, even as forefront science projects get more refined and more sophisticated there is still room for the student, or the amateur, or the citizen scientist to make discoveries. BIG important discoveries. Eureka damn it!

Right now astronomers all over the world are mobilized observing SN2014J with every instrument they can. That includes astronomers at Adler. Gayle Ratliff a graduate student researcher at Adler and IIT is in Arizona right now searching for high energy gamma rays using the VERITAS observatory. Stay tuned to this blog to find out more about what they discover. 

The so called single degenerate scenario: A giant star feeds matter on to white dwarf creating a disk of material as it does so. Image credit: Adler Planetarium and Robert Hurt, from The Searcher.

The so called single degenerate scenario: A giant star feeds matter on to white dwarf creating a disk of material as it does so. Image credit: Adler Planetarium and Robert Hurt, from The Searcher.

There are still some important things that we don’t understand such as what triggers this type of supernova. We believe they occur when an evolved star know as a white dwarf exceeds a certain mass limit (the Chandrasekhar Limit 1.44 times the mass of the Sun). When the star reaches that limit, carbon burning initiates and the supernova explodes. But how does it surpass that mass limit. One idea is that if a white dwarf is in a binary system with a red giant star, that star might feed material onto the white dwarf, eventually triggering a supernova. Another idea is that perhaps two white dwarfs are in orbit with each other, eventually spiraling in and merging which triggers the supernova. Because SN2014J was so close and M82 so well observed beforehand we will likely be able to determine which scenario took place in this case.

To find out more I encourage you to come down to the Space Visualization Laboratory and attend Astronomy Conversations where you can see the latest observations of M82 and see the state of art computer simulations of Type Ia supernova detonation models. If weather allows we hope to be observing M82 and SN2014J from Adler’s Doane Observatory, stay tuned for that as well.

Written by Mark SubbaRao, astronomer and director of the Space Visualization Lab at the Adler Planetarium. You can follow Dr. SubbaRao on Twitter @marksubbarao.

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