猎户四边形星团

猎户四边形星团是位于猎户座的M42核心的一个致密的疏散星团。它是由伽利略发现的。在1617年2月4日，他简要绘制了其中三颗恒星（A,C,D），但没注意到周围的星云状物质。Galileo Galilei: Siderius Nuncius, Venice, 1610. English Translation published at Bard College, Hudson NY" October 9, 2003 English Translation  Original Latin version Tom Pope and Jim Mosher: Galilean telescope homepage"  March 17, 2006  , "Some have expressed puzzlement that in his text Galileo does not mention the nebulosity (known in modern nomenclature as M42) enveloping these stars. ... Galileo believed, as he explains in Sidereus Nuncius, that what looks nebulous to the eye is resolved into stars by his telescope; what looks nebulous through his telescope could presumably also be resolved into stars by a still larger and more powerful telescope. Hence, a diffuse glow would be, more than anything, an indication of the limitations of his telescope and not particularly worthy of special note." Tom Pope and Jim Mosher: Page on Galileo's February 4, 1617 notebook drawing of the Trapezium region, May 2, 2006 "Perhaps significantly, Galileo makes no mention of having noticed the now well-known gas cloud, M42, surrounding the Trapezium stars." . 第四个成员星（B）在1673年被几个观测者辨认出，之后更多的成员被发现；到了1888年总共发现了8颗成员星。后来其中几颗恒星被确定为是双星。在良好的观测条件下，业余观测者的5英寸口径望远镜可以分解出6颗恒星。

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Category:疏散星团
Category:猎户座