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Credit: ESO
Tuesday, Oct. 6, 2015: Globular cluster NGC 6553 lies approximately 19,000 light-years away in the constellation of Sagittarius. Astronomers have discovered…Read More »

a microlensing mystery in this field of view. In microlening, the gravitational field of a foreground object bends the light of a more distant object, creating an amplified image of the distant object. The object creating the microlensing effect in NGC 6553 bent the light of a red giant star in the background (marked with arrow). If this object lies in the cluster (and this object only has a 50 percent chance of existing), the object could be a black hole with a mass twice that of the sun, making it the first of its kind discovered in a globular cluster. It would also represent the oldest known stellar-mass black hole ever discovered. However, further observations must be made to determine the nature of this lensing object. Image released Oct. 5, 2015.

— Tom Chao   Less «
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