Call it the stellar version of the Slim-Fast diet. A red giant star named R Sculptoris shed about 1000 Earth masses of carbon-rich material 1800 years ago over a period of just 2 centuries. Located 950 light-years away and visible through binoculars, the star is red even for a red giant because the carbon it has forged has reached the stellar surface, where it forms molecules that absorb blue and violet light. Astronomers reporting online today in Nature detected the ejected gas from submillimeter radiation that its carbon monoxide molecules emit. As the star expelled the material, it created a spiral pattern just as a rotating lawn sprinkler does, because a previously unknown stellar companion is dancing around the red giant and causing it to move in response. (In the image, R Sculptoris is at center, red marks the densest gas, and the green curve is the spiral the scientists have fit to the data.) The red giant will eventually cast off its entire carbon-rich envelope, leaving behind only a small, hot core, while its lost material spreads into space, ready to enrich planets that have yet to be born with the key element on which all terrestrial life is based.
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