dark star

noun Astronomy.

an invisible member of a binary or multiple star system.

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British Dictionary definitions for dark star

dark star

noun

an invisible star known to exist only from observation of its radio, infrared, or other spectrum or of its gravitational effect, such as an invisible component of a binary or multiple star

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012