The P13 is a black hole along the outer edge of the NGC7793 galaxy located around 12 million light years away from the Earth. It's very luminous compared to others of its kind but as it turns out, this has nothing to do with the black hole's size. Instead, P13 is consuming gas from a donor star faster than what was previously thought possible.
In a study published in the journal Nature, P13's unusual eating habits offered new insight on how black holes behaved. P13 was brighter than other black holes and this was initially attributed to its size.
According to Dr. Roberto Soria, an astronomer with the International Centre for Radio Astronomy Research based in Curtin University, it was always believed that the fastest a black hole could consume gas and consequently produce light was tied to its size. It made sense then to think that P13 was simply bigger than the usual black hole in the Milky Way.
But when Dr. Soria and colleagues measured P13's mass, it turned out to be actually small despite being brighter than the Sun by at least a million times. It was then that researchers realized just how much the black hole was consuming.
P13's donor star is a supergiant 20 times heavier than the Sun. Its sides were observed to be brighter where P13 is because the black hole's X-rays illuminated the star. Using this observation, researchers measured the time the star and P13 take to rotate around each other, modeling velocity between the two as well as their orbital shape.
From that information, they were able to work out that P13 is actually at least 15 times smaller than the Sun.
Given the small black hole's hearty appetite, Dr. Soria likened P13 to Takeru Kobayashi, the Japanese eating champion who is also of small stature. He said Kobayashi showed that size is not always a factor in competitive eating, an idea that may also apply to black holes and their donor stars.
If Kobayashi was P13, the rate at which the black hole is eating gas is equivalent to 100 billion hotdogs every minute. At that speed, the black hole will swallow its donor star in under a million years. If it were sitting next to the Earth, it would finish up the planet in less than a year.
The study "A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source" was led by University of Strasbourg's Dr. Christian Motch.