NASA has released a photo taken by the NASA/ESA Hubble Space Telescope of a small region on the edge of the dark nebula Caldwell 99.
Caldwell 99 is a dark nebula — a dense cloud of interstellar dust that completely blocks out visible wavelengths of light from objects behind it — located approximately 600 light-years away in the southern constellation of Crux.
Having been viewed by stargazers for millennia, the object has no discoverer, but Europeans first learned of it from Spanish explorer Vicente Yáñez Pinzón in 1499.
Otherwise known as the Coalsack Nebula, Caldwell 99 is approximately 100 light-years across.
“The object at the center of the image is a much smaller protoplanetary nebula,” Hubble astronomers said.
“The protoplanetary nebula phase is a late stage in the life of a star in which it has ejected a shell of hydrogen gas and is quickly heating up.”
“This stage only lasts for a few thousand years before the protoplanetary nebula’s central star reaches roughly 30,000 K.”
“At this point, the central star is producing enough energy to make its surrounding shell of gas glow, becoming what’s known as a planetary nebula.”
The image is made up of observations from Hubble’s Advanced Camera for Surveys (ACS) in the infrared and optical parts of the spectrum.
Several filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter.
The astronomers took these observations to learn more about the evolution of protoplanetary nebulae into planetary nebulae.