出典:Wikipedia
出典:『Wikipedia』 (2011/02/23 04:00 UTC 版)
NGC 2346 (also known as the Butterfly Nebula) is a planetary nebula near the celestial equator in the Monoceros constellation. It is bright and conspicuous and has been extensively studied. Among its most remarkable characteristics is its unusually cool central star, which is a spectroscopic binary, and its unusual shape.