Star Scarab

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

This image reminds me of a beetle, a star scarab.

NASA‘s Hubble Space Telescope gives us a great chance to explore the inside of a planetary nebula in this image of NGC 2818. Start exploring by finding the white central star. This star shed its outer layers after it ran out of the hydrogen fuel needed to sustain nuclear fusion in its core. Our Sun will change in a similar way but not for another 5 billion years. The expanding bubble of gas and dust form the planetary nebula. The central star’s radiation excites atoms within the gas cloud, causing it to glow. Right now, the core is super hot. Over the next billion years, the central star will slowly cool off becoming a white dwarf. Eventually, this white dwarf will dim and become a cooling ember in space.

Look at the color boundaries within the nebula. Can you see changes in the way the gas and dust flow in these areas? What are your ideas for the color changes toward the edge of the nebula?

NGC 2818 is found within an open star cluster. Open star clusters are groups of tens or hundreds of stars that formed at about the same time and are held together by gravity. The Pleiades are an example of an open star cluster. However, the planetary nebula is not a part of the star cluster. By chance, NGC 2818 lines up with the star cluster as viewed from Earth.

NGC 2818 is about 5 light-years across. The nebula is found about 10,000 light-years away toward the southern constellation of Pyxis, the compass. Pyxis is Latin for a mariner’s compass. In the 1700s, French astronomer Nicolas Louis de Lacaille named this small and faint constellation. The constellation is found near the old constellation of Argo Navis, the ship Argo from the Greek myth about Jason and the Argonauts.

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The ancient peoples saw pictures in the sky. From those patterns in the heavens, ancient storytellers created legends about heroes, maidens, dragons, bears, centaurs, dogs and mythical creatures...
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