New Findings in our Knowledge of the Universe
The newly-discovered supernova provides astronomers an opportunity to hone our knowledge of the universe, and you can help!
Published January 23, 2014
By Academy Contributor
Astrophysicist and science blogger @CatherineQ summed it up beautifully:
@CatherineQ Great thing about Type 1a #supernova is that they all have similar characteristics and that enables us to use them to determine distances.
@CatherineQ But here we are – 12 million years later – perfectly poised in time to view this amazing exploding death of a star. How cool!
Indeed! About 12 million years ago in the M82 galaxy, also known as the Cigar Galaxy, a white dwarf star in a binary system (in which two stars orbit one center of mass) exploded into a supernova. Light from the event recently arrived on earth and was first observed by a University College of London astronomy observation workshop led by Dr. Steve Fossey.
“We were expecting a standard quick look through the telescope and a chance to use the camera for the first time before the clouds moved in, that’s all. When we started looking and Steve began getting more excited none of us could really believe what was going on. I can’t wait to get back on a telescope next week now,” says UCL student Matt Wilde.
M82 is a “mere” 12 million light years away from earth—pretty close by astronomy standards. Originally dubbed PSN J09554214+6940260 and now assigned the catchier name 2014J, the supernova will likely be visible through binoculars in the coming weeks. You can watch a video on locating M82 and 2014J here.
For professional astronomers this is an opportunity to calibrate our maps of space and better understand dark energy, the mysterious accelerator of universal expansion. This is because 2014J is a Type 1a supernova, and all Type 1a supernovae are the same (well, mostly, but more on that soon…).
More Detailed Knowledge about the Expansion of the Universe
They occur when the mass of white dwarf stars, super-dense remnants of “dead” stars, exceeds a mass limit of about 1.4 solar masses. In a binary system, the dense white dwarf’s extreme gravity pulls matter from the sister star, eventually crossing the mass threshold—called the Chandrasekhar limit after discoverer Subrahmanyan Chandrasekhar—igniting the nuclear chain reaction of supernovae.
The mass threshold is the same for any white dwarf star due to the processes of stellar evolution and principles of nuclear physics. This means that the progenitor conditions and resultant luminosity are homogenous throughout this class of supernova. National Geographic breaks it down nicely here. For a more detailed explanation, the University of Michigan offers helpful notes online.
Objects of uniform brightness appear brighter or dimmer depending on distance from the observer, following the inverse square law. A Type 1a supernova that appears a quarter as bright as another Type 1a supernova is twice as far away from us, allowing the supernovae to be used as yardsticks—standard candles in astro-jargon. They can thus be used to refine measurements of galactic distances, helping to understand how the universe is laid out and how the layout is changing over time. More detailed knowledge about the expansion of the universe may offer clues about the dark energy hurrying that expansion.
But here’s the thing: standard candles lack standardization, and the variation leads to some yet-unanswered questions. Younger stars form under more metallic conditions than older stars, because older generations of stars create and expel heavy elements.
A Call to Amateur Astronomers
“This means the stars that are forming today are forming out of materials that were just a twinkle in a young giant star’s eye some day in the past. The first stars were almost pure hydrogen and helium. Those stars have very different physics from today’s stars. Metals moderate the formation of stars, making stars form smaller and burn in a more controlled way. When white dwarf stars first started forming, they had fewer metals than modern white dwarfs and that could have effected how supernovae explode, causing supernovae to vary as a function of time in ways that we don’t know about,” explains astronomer Dr. Pamela L. Gay.
Importantly, the (to us) newness of 2014J means that astronomers can compare the star’s before and after supernova data, which will help suss out information about the components of its spectrum. And you can help! Phil Plait writes how and why:
“If you are an amateur astronomer, get images! And if you observed M82 recently, you may have ‘pre-discovery’ images of it, taken before it was officially discovered. Those are critical for understanding the behavior of the supernova. If you do, report it to the CBAT (but make sure you read the instructions first; they don’t want images, just reports of magnitudes and so on). Given the fact that it’s nearby, up high for so many observers, and caught so early, this may become one of the best-observed supernovae in modern times.”
Also read: What Caused the Big Bang?
