Astronomers have discovered a black hole with voracious appetite for devouring gas. Named P13, the black hole consumes gas from a nearby star about 10 times faster than previously believed possible.
P13 was discovered over thirty years ago with the aid of the Einstein X-ray telescope of the National Aeronautics and Space Administration (NASA). Located about 12 million light-years away in the borders of galaxy NGC7793, this black hole belongs to a group of astronomical bodies known as ultra-luminous X-ray sources (ULXs), which are more luminous than typical stellar activities but not as bright as an active galactic nucleus.
"These are the champions of competitive gas eating in the Universe, capable of swallowing their donor star in less than a million years, which is a very short time on cosmic scales," International Centre for Radio Astronomy Research (ICRAR) astronomer Roberto Soria said.
Soria said that it is generally assumed that the size of a black hole determines its speed at swallowing gas and producing light so P13 was initially thought to be massive because it is a million times brighter than the sun.
When Soria and his colleagues measured the mass of the black hole, however, they realized that it is not as big as previously thought. It was then that they pointed out the cause of P13's incredible brightness: its hungry appetite for gas.
P13 has a companion star, the B9Ia donor star, a blue supergiant up to 23 times the mass of the sun. As the black hole sucks gas from this star, the matter gets very hot and bright, which causes the black hole's brilliance.
The amount of light that P13 produces suggests that it consumes gas equivalent to the mass of the moon every three weeks or the mass of the Earth every four years, which is significantly more than the maximum amount posited by the Eddington limit on the maximum luminosity a star can achieve.
By observing the binary system for a period of eight years, the astronomers learned that P13 and its donor star complete an oval-shaped orbit around each other every 64 days. Describing their findings in the journal Nature on Oct. 8, Soria and colleagues also reported that their analysis revealed that P13, despite its brightness, is less than 15 times the mass of the sun.
"By modelling the strong optical and ultraviolet modulations arising from X-ray heating of the B9Ia donor star, we constrain the black hole mass to be less than 15 solar masses," the researchers wrote.
