October 24, 2011 - All Eyes on Oldest Recorded Supernova

This image combines data from four different space telescopes to create a multi-wavelength view of all that remains of the oldest documented example of a supernova, called RCW 86. The Chinese witnessed the event in 185 A.D., documenting a mysterious "guest star" that remained in the sky for eight months. X-ray images from the European Space Agency's XMM-Newton Observatory and NASA's Chandra X-ray Observatory are combined to form the blue and green colors in the image. The X-rays show the interstellar gas that has been heated to millions of degrees by the passage of the shock wave from the supernova.

Infrared data from NASA's Spitzer Space Telescope, as well as NASA's Wide-Field Infrared Survey Explorer (WISE) are shown in yellow and red, and reveal dust radiating at a temperature of several hundred degrees below zero, warm by comparison to normal dust in our Milky Way galaxy.

By studying the X-ray and infrared data together, astronomers were able to determine that the cause of the explosion witnessed nearly 2,000 years ago was a Type Ia supernova, in which an otherwise-stable white dwarf, or dead star, was pushed beyond the brink of stability when a companion star dumped material onto it. Furthermore, scientists used the data to solve another mystery surrounding the remnant -- how it got to be so large in such a short amount of time. By blowing a wind prior to exploding, the white dwarf was able to clear out a huge "cavity," a region of very low-density surrounding the system. The explosion into this cavity was able to expand much faster than it otherwise would have.

This is the first time that this type of cavity has been seen around a white dwarf system prior to explosion. Scientists say the results may have significant implications for theories of white-dwarf binary systems and Type Ia supernovae.

RCW 86 is approximately 8,000 light-years away. At about 85 light-years in diameter, it occupies a region of the sky in the southern constellation of Circinus that is slightly larger than the full moon.

Image credit: NASA/ESA/JPL-Caltech/UCLA/CXC/SAO

All That Remains of Exploded Star

Infrared images from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer (WISE) are combined in this image of RCW 86, the dusty remains of the oldest documented example of an exploding star, or supernova. It shows light from both the remnant itself and unrelated background light from our Milky Way galaxy. The colors in the image allow astronomers to distinguish between the remnant and galactic background, and determine exactly which structures belong to the remnant.

Dust associated with the blast wave of the supernova appears red in this image, while dust in the background appears yellow and green. Stars in the field of view appear blue. By determining the temperature of the dust in the red circular shell of the supernova remnant, which marks the extent to which the blast wave from the supernova has traveled since the explosion, astronomers were able to determine the density of the material there, and conclude that RCW 86 must have exploded into a large, wind-blown cavity. The infrared images, when combined with optical and X-ray data, clearly indicate that the source of the mysterious object seen in the sky over 1,800 years ago must have been a Type Ia supernova.

Spitzer and WISE light with wavelengths of 24 and 22 microns, respectively, is colored red. Shorter wavelength infrared light from WISE is blue, cyan and green.

Image credit: NASA/JPL-Caltech/UCLA