Thursday, March 9, 2017

A Stellar Spiral

Two images of nebula LL Pegasi, in visual light by Hubble and in radio waves by ALMA (below), which brings out the spiral structure:
Although it looks like the pattern of a shell on the beach, this intriguing spiral is in fact astronomical in nature. The Atacama Large Millimeter/submillimeter Array (ALMA) captured this remarkable image of a binary star system, where two stars — LL Pegasi and its companion — are locked in a stellar waltz, orbiting around their common centre of gravity. The old star LL Pegasi is continuously losing gaseous material as it evolves into a planetary nebula, and the distinct spiral shape is the imprint made by the stars orbiting in this gas.

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