Here's some images of several low-mass stars in their death throes, all taken with the Hubble Space Telescope.
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An HST image of the Cygnus Egg (AFGL 2688) in scattered light. Astronomers classify the Egg as a proto planetary nebula, i.e. an evolved star which has blown off much of its outer envelope, but has not completely exposed its hot stellar interior. When this happens, the outer envelope will become ionized and we'll be looking at a young planetary nebula. The Egg has not yet reached this stage, so we're seeing light scattered from the dust around the source. Even though the central star is spherical, the geometry of the scattered light is very complicated. One of the outstanding mysteries in the study of how stars die is how this highly non-spherical geometry develops. |
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An HST image of the young planetary nebula NGC 7027. This nebula is a strong source of infrared emission (including emission from PAH molecules). The outer envelope has detached from the stellar interior, but this optical image only penetrates down to the thick dust cloud obscuring the central source. In the infrared, where the dust is transparent, astronomers can see the young planetary nebula beneath. |
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An HST image of the Hourglass Nebula (MyCn 18). This source has evolved beyond the stage of the Cygnus Egg and NGC 7027, showing a planetary nebula in its full glory. Notice the complicated structure of the ionized shells, loops, and filaments. Astronomers don't understand how such a geometry forms. |
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An HST image of another beautiful planetary nebula, the Cat's Eye Nebula (NGC 6543). |
Last modified 11 December, 2014. © Gregory C. Sloan.
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