The Asymmetric Nebula Surrounding Wolf-Rayet Star 18
Why does the nebula around the star WR-18 shine brighter on one side?Also known as NGC 3199, this active star and its surrounding nebula lie about 12,000 light-years away toward the nautical southern constellationof Carina.The featured deep image has been highly processed to bring out filamentary details of the glowing gas in the bubble-shaped nebula. The nebula is about 75 light-years across.Near the nebula's center is aWolf-Rayet star, WR-18, which is a massive, hot, short-lived star that generates an intense and complex stellar wind.In fact, Wolf-Rayet stars are known to create nebulaswith interesting shapesas their powerful winds sweep up surroundinginterstellarmaterial.In this case, the bright right edge was initially thought to indicate that abow shock was being produced as the star plowed through a uniform medium, like a boat through water.Recent measurements and analyses, however, have shown the star is not moving quickly toward the bright edge.A more likely explanation has emerged that thematerial surrounding the star is not uniform, butclumped and denser near the bright edge.
Image Credit & Copyright: Alex Woronow
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