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PigSkinPoppa t1_iu9uyff wrote

How do they know that there is a black hole in the cross hairs of this photo? Please educate me and explain the photo. :)

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PorkStroganoff t1_iu9vpbo wrote

If a star move in a constant direction forming a circle and theres no other luminous object around so the conclusion is that a Black Hole is there

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Azelicus t1_iuditlf wrote

You don't detect black holes in a single photo.

You either detect them by studying the orbit of a close stellar companion (which seems to orbit a massive, non visibile object) or the effect of the distortion they produce on light passing close to them (an effect called "gravitational lensing").

For those reasons, we can't usually detect small, single black holes, even relatively close to us.

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