This black hole occasionally releases dramatic outbursts of X-ray light. One of those outbursts happened in 1917, and was how the system was discovered. During an outburst in 1975, V616 Monocerotis brightened over 100,000 times, becoming the brightest X-ray source known at the time.
Scientists suspect the black hole Cygnus X-1 began life as a star 40 times the mass of the sun. It likely collapsed directly to form a black hole some 5 million years ago — around the same time the first mammoths show up in fossil records on Earth.
This black hole is either the smallest ever found that formed from the collapse of star, or it could be a neutron star — the verdict is still out.
Its mass isn’t well measured, so scientists are uncertain if Cygnus X-3 actually holds a black hole or a neutron star. The object is paired with a Wolf-Rayet star — an incredibly bright object with an unusual distribution of elements, particularly on its surface — that is one of the brightest stars in the galaxy. The star will likely become a black hole itself fairly soon, so stay tuned — for the next million years or so.
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