Kepler’s Supernova Remnant. Credit: NASA / CXC / Univ of Texas at Arlington / M. Millard et al.
Astronomers have used NASA‘s Chandra X-ray Observatory to record material moving away from the side of an exploding star at speeds faster than 20 million miles per hour. This is about 25,000 times faster than the speed of sound on Earth. The Kepler supernova remnant is the pound of a star about 20,000 light-years from Earth in our planet Milky Way galaxy.
In 1604, early astronomers, including Johannes Kepler who became the namesake of the object, saw the supernova explosion that destroyed the star. What Johannes Kepler did not know at the time was that the new object he saw was caused by a small dense star that exceeded a mass limit after interacting with a companion star, triggering a thermonuclear explosion. Today, astronomers call this a Type Ia supernova, and they can study the superheat debris that expands in space and glows brightly in X-rays.
Researchers estimate the velocities of different clumps in Kepler by analyzing Chandra X-ray spectra, the scattering of light that gives the amount of X-rays at different wavelengths. This allowed astronomers to use the Doppler effect to convert changes in the wavelength of functions in the X-ray spectrum into velocities along Chandra’s line of sight to the rest. They combined this information with measurements of the change in position of clumps between Chandra images obtained in 2000, 2004, 2006 and 2014. This allowed the astronomers to measure movements perpendicular to our line of sight and then observe the velocities of each clump.
The high velocities in Kepler are equal to what scientists have seen only days or weeks after the explosion in supernova explosions in other galaxies. This may mean that some clogs in Kepler have barely slowed down due to collisions with material around the remains in the nearly 400 years since the explosion.
Scientists are still trying to determine exactly why these clogs in Kepler move so fast. It could be that it was a particularly powerful supernova explosion, or perhaps the environment in which the pound moves in fewer places is less dense. However, this object will be something to see in the coming years.
