Unusual objects that look like gas and behave like stars have been spotted near our Galaxy’s enormous black hole, astronomers have said.
Four new discoveries have been found closely orbiting a supermassive black hole called Sagittarius A* located some 26,000 light-years away from Earth.
They join G1 and G2, which were found in 2005 and 2014 respectively, intriguing scientists because they seem to be compact most of the time but stretch out as they get closer to the black hole during their orbit.
These orbits are also a lot longer than the 365 days Earth takes to move around our sun, ranging from about 100 to 1,000 years.
Researchers at the University of California, Los Angeles, have fittingly named the newcomers G3, G4, G5 and G6.
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Writing in the Nature journal, the group explained its belief that all six were once binary stars – a pair of stars which orbit each other – later merging as one due to the supermassive black hole’s powerful gravitational force.
However, this merging process is not done overnight – it takes more than one million years to complete, said co-author Andrea Ghez.
“Mergers of stars may be happening in the Universe more often than we thought, and likely are quite common,” she explained.
“Black holes may be driving binary stars to merge. It’s possible that many of the stars we’ve been watching and not understanding may be the end product of mergers that are calm now.
“We are learning how galaxies and black holes evolve. The way binary stars interact with each other and with the black hole is very different from how single stars interact with other single stars and with the black hole.”
The team is already looking into other potential objects that may be part of the same family.
It says the research will help shine a light on what is happening in the majority of galaxies in our Universe – though Earth is quite a distance from the action, “in the suburbs compared to the centre of the Galaxy”, Ms Ghez added.
Reader Q&A: If you had a strong enough magnet, could you pull something magnetic out of a black hole?
Asked by: Kealan Brion, Whitby
Astronomers have found that the magnetic field strengths near supermassive black holes can be as strong as their intense gravitational fields. In fact, these magnetic fields are able to expel material from the vicinity of the black hole to form highly energetic outflows called ‘jets’.
However, this process is not acting on material that has already passed beyond the black hole’s event horizon (where the gravity is so strong that not even light can escape). Such material would need to be accelerated to at least the speed of light to escape, and Einstein’s General Relativity shows us that this would require an infinite amount of energy. No magnet, however powerful, could provide this.