Thousands of light years away in the constellation Draco shines the Cat's Eye planetary nebula. Formed when a star transitions into a red giant and sheds its outer layers, the planetary nebula will shed gas until only a hot, dense core of a white dwarf is left behind.

A Cat's Eye in the Stellar Dragon

The Cat's Eye nebula is 3,000 light years away in the constellation Draco, and is only partway through the transition from red giant to white dwarf. The transition occurs as the hot, dense core drives fast winds, spreading the ejected gas into a graceful nebula. A white dwarf has run through its reaction pathways, with no more viable fusion outlets. Instead, the star is supported from collapse by electron degeneracy pressure, radiating its remaining energy into space. Over time, the hot, bright white dwarf will cool and dim through red and brown before sputtering out completely as a cold, black dwarf. Theoretically, the universe is too young to have any black dwarfs yet, but one day space will be littered with them.

The Cat's Eye is a planetary nebula, but planets have nothing to do with this dying star. The name is a historical relict left from early attempts at cataloging astronomical objects, when the colourful gasses reminded the cataloger of nearby gas giants.

The composite image is a blend of Chandra X-ray Observatory data in blue, and visible light data from the Hubble Space Telescope in red and purple. The gas cloud is expanding at roughly 4 million miles per hour, while the star should collapse into a white dwarf in a few million years.

Image credit: X-ray: NASA/CXC/SAO; Optical: NASA/STScI. For more beautiful X-Ray images, check out this view of a galaxy collision. For another nebula, admire this one in infrared.