Sh 2-310 is a nebula in the slightly southern constellation of Canis Major. It is one of the largest H II regions known in the Milky Way. It is ionized by the stars UW and Tau Canis Majoris. The latter is the brightest star of the open cluster NGC 2362, which is located near the nebula, while another member, the red hypergiant VY Canis Majoris, is located near the nebula's rim.
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