Supernova fans have had a good week, with two beautiful images related to the explosive stars being released by two different agencies. The European Southern Observatory’s Very Large Telescope at the Paranal Observatory in Chilé is responsible for the photograph above of NGC 1637, which is a spiral galaxy of the same type as our Milky Way located about 35 million light-years away.
The astronomers have been observing the galaxy since 1999 when the Lick Observatory in California first reported the discovery of the supernova there. The exploding star, named SN 1999em, was at one point eight times the mass of our own sun before it ultimately destroyed itself in a core collapse that ended in the violent explosion. The ESO is tracking how it slowly fades over time.
The second photo was released by NASA, which observed the remnants of an even more famous supernova with NASA’s Chandra X-ray observatory.
Called Kepler’s supernova because it was intensively studied by one of history’s greatest astronomers, Johannes Kepler, it’s the last known supernova that exploded brightly enough to be seen with the naked eye from our earth. It was first seen on October 9, 1604 and was reportedly brighter than every star in the sky, as well as brighter than every visible planet except Venus.
For a supernova, it’s impressively close to our planet — a mere 20,000 light-years away, which is quite a bit closer than the 35 million light-years that separate us from NGC 1637.
NASA said that they now know what caused the thermonuclear explosion of what was once a white dwarf star. It was more than the core collapse seen in the NGC 1637 object. An X-ray analysis has revealed that the trigger for this explosion was a red giant star coming too close to the white dwarf.
The Kepler supernova is the type considered most dangerous to life on earth, but the explosion would probably have to occur within 100 light-years to flood our planet with lethal amounts of radiation.
We can relax and just enjoy the pretty pictures. There aren’t enough vulnerable stars close enough to cause astronomers to fear that we’ll be wiped out by an exploding supernova.
[Kepler Credits: X-ray: NASA/CXC/NCSU/M.Burkey et al; Infrared: NASA/JPL-Caltech]
[photo of Spiral galaxy NGC 1637, the site of a fading supernova, courtesy ESO]