OLD SUPERNOVA SEEN IN SUPER SIZE: BIG PIC

OLD SUPERNOVA SEEN IN SUPER SIZE: BIG PIC





Sept. 13, 2012 -- This colorful bubble of twisted strands of gas is all that remains of a star -- or, more technically, a pair of stars -- that exploded tens of thousands of years ago, lighting up the night sky here on Earth for several weeks in 1604 and attracting the attention of German astronomer Johannes Kepler.


Kepler's supernova remnant is located within the constellation Ophiuchus, but astronomers haven't been able to accurately pin down its distance or how it was formed. Now, with new observations by NASA's Chandra X-ray Observatory, the structure and scale of the remnant are clearer than ever before... and it turns out the stellar explosion was a much larger -- and distant -- event than anyone thought.


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Kepler's supernova remnant is what's left of a Type Ia supernova, the end result of a white dwarf star that's been "feeding" on material drawn off a companion star until a critical mass (aka the Chandrasekhar limit) is reached and rapid nuclear reactions are triggered, blowing the pair apart in a powerful, brilliant explosion equal to the light of 5 billion suns.


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In fact the brightness of Type Ia supernovae is so consistent and well-known, astronomers use them to gauge intergalactic distances.


The distance to Kepler's remnant, however, has proven to be more elusive. Data gathered with Chandra over the span of more than 200 hours in 2006 has led to the image above, which shows varying X-ray energy levels emitted by the still-expanding gas of the supernova as well as the optical light shed by stars. We can see asymmetrical arcs of X-ray-bright gas in the upper regions of the remnant, which some astronomers are suggesting is the result of the supernova's ejected material plowing through the surrounding, slower-moving interstellar material.


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In addition the spectra of these bright arcs reveals the presence of a large amount of iron, which indicates the explosion must have been very powerful. The original white dwarf may have even been emitting nova eruptions prior to the ultimate supernova.


Based on this cosmic forensic work by the Chandra researchers, the distance to Kepler's supernova remnant is estimated to be anywhere from 16,000 to over 23,000 light-years away -- a large range, yes, but well over the previous estimate of 13,000 light-years.


As the supernova's remains expand so does our ability to observe it, thereby understanding a little bit more about how our Universe works!


Read more on the Chandra site here.


-- by Jason Major


Image credit:X-ray: NASA/CXC/SAO/D.Patnaude, Optical: DSS