A supermassive black hole 7,200 light years from the Earth is aroud 50% larger than originally suspected, a new study has revealed.
Named Cygnus-X-1, it was the first black hole confirmed by astronomers, after first being discovered in 1964 when two Geiger counters were sent to space on a rocket.
Its final confirmation as a black hole in 1990 lost legendary British physicist Sir Stephen Hawking a bet he made with Professor Kip Thorne over its status.
Thanks to a combination of new techniques and more advanced telescopes, including the continent sized Very Long Baseline Array, astronomers have been able to determine that the stellar phenomenon is 21 times the mass of the Sun.
Astronomers from Curtin University in Australia say this is the record for a black hole that has been directly observed as a result of matter falling into it.
The new measurements also found it was 20% further away from the Earth than was previously thought – based on the original findings from 1964.
Thanks to a combination of new techniques and more advanced telescopes, including the continent sized Very Long Baseline Array, astronomers have been able to determine that the stellar phenomenon is 21 times the mass of the Sun
Astronomers used the Very Long Baseline Array – with telescopes across the US – to make their measurements of the black hole and partner star
Cygnus-X-1: First radio source to be confirmed as a black hole
Cygnus-X-1 is a supermassive black hole 7,200 light years from the Earth.
It was first discovered in 1964 when a pair of Geiger counters were sent up on a sub-orbital rocket flight.
It was the strongest X-ray sources ever seen from Earth and is one of the most studied supermassive black holes.
Recent studies found it was 20% further away and 50% larger than initial 1960s observations suspected.
The black hole is in a binary system with a blue supergiant – orbiting each other every five days.
Stellar wind from the star provides material for the black hole with matter heated and pouring out as x-ray jets.
The discovery it was a black hole lost Professor Stephen Hawking a bet with Professor Kip Thorne – the late Hawking had to buy a years subscription to Penthouse for Thorne.
The Very Long Baseline Array, that was used to make the new measurements, is a continent-sized radio telescope made up of 10 dishes spread evenly across the US and its territories – from the US Virgin Islands to New Hampshire.
This wide distribution of dishes allows astronomers to piggyback off the movement of the Earth around the Sun to measure the distance of far away objects.
Lead author Professor James Miller-Jones, of Curtin University said viewing the same object from different locations allows astronomers to calculate its distance by measuring how far the object appears to move relative to the background.
‘If you hold your finger out in front of your eyes and view it with one eye at a time, you’ll notice your finger appears to jump from one spot to another. It’s exactly the same principle,’ he said.
‘Over six days we observed a full orbit of the black hole and used observations taken of the same system with the same telescope array in 2011.
‘This method and our new measurements show the system is further away than previously thought, with a black hole that’s significantly more massive.’
What is more, its blue supergiant companion star is 22 times larger than the Sun with a mass that is 41 times greater than our host star, the researchers discovered.
The black hole and its giant partner star orbit each other every five and a half days.
The star’s wind absorbs radio waves from the black hole’s jets – a discovery that improved the accuracy of the calculations allowing the researcher to him in the true size and distance from Earth of the phenomenon.
For such a massive black hole to exist the star from which it formed must have lost less mass over its lifetime than expected.
Bigger black holes have been identified much further away from the Earth but only by gravitational waves – invisible yet incredibly fast ripples in space.
Cygnus-X-1 was discovered in 1964 when a pair of Geiger counters were carried on board a sub-orbital rocket launched from New Mexico.
The object was the focus of a wager a decade later with Professor Hawking betting American physicist Professor Kip Thorne it was not a black hole.
It was four years of Private Eye for him – against a subscription to Penthouse magazine for Thorne. Hawking finally conceded in 1990.
Astronomers from Curtin University in Australia say this is the record for a black hole that has been directly observed as a result of matter falling into it
For such a massive black hole to exist the star from which it formed must have lost less mass over its lifetime than expected
VERY LONG BASELINES ARRAY: TELESCOPES SPANNING THE US
The Very Long Baseline Array is a series of telescopes spanning the US and its territories.
Construction started in 1986 and was completed in 1993 with the first observation the same year.
The $85 million network of telescopes spanning from the US Virgin Islands to New Hampshire, costs $10 million a year to operate.
Each of the receivers includes a 25 meter parabolic dish antenna.
Signals from each antenna are recorded on a bank of 1TB hard drives, with the data time-stamped using atomic clocks.
They are then taken for processing on powerful computers that correct for the rotation of the Earth, shifts in the Earth’s crust and other errors.
Co-author Professor Ilya Mandel, of Monash University, Melbourne, said the black hole is so massive it’s actually challenging how astronomers thought they formed.
He said: ‘Stars lose mass to their surrounding environment through stellar winds that blow away from their surface.
‘But to make a black hole this heavy, we need to dial down the amount of mass that bright stars lose during their lifetimes.
‘The black hole in the Cygnus X-1 system began life as a star approximately 60 times the mass of the Sun and collapsed tens of thousands of years ago.
‘Incredibly, it’s orbiting its companion star – a supergiant – every five and a half days at just one-fifth of the distance between the Earth and the Sun.
‘These new observations tell us the black hole is more than 20 times the mass of our Sun – a 50 per cent increase on previous estimates.’
Co-author Xueshan Zhao, a PhD candidate at the Chinese Academy of Sciences. worked out its speed from the updated mass and distance measurements.
She said: ‘I was able to confirm that Cygnus X-1 is spinning incredibly quickly – very close to the speed of light and faster than any other black hole found to date.’
The researchers said the study published in Science sheds fresh light on the lives and deaths of the most massive stars in the cosmos.
The new measurements also found it was 20% further away from the Earth than was previously thought – based on the original findings from 1964
The star’s wind absorbs radio waves from the black hole’s jets – a discovery that improved the accuracy of the calculations allowing the researcher to him in the true size and distance from Earth of the phenomenon
Next year, the world’s biggest radio telescope–the Square Kilometre Array (SKA)–will begin construction in Australia and South Africa.
Prof Miller-Jones added: ‘Studying black holes is like shining a light on the Universe’s best kept secret – it’s a challenging but exciting area of research.
‘As the next generation of telescopes comes online, their improved sensitivity reveals the Universe in increasingly more detail, leveraging decades of effort invested by scientists and research teams around the world to better understand the cosmos and the exotic and extreme objects that exist.
‘It’s a great time to be an astronomer.’
The findings have been published in the journal Science.
BLACK HOLES HAVE A GRAVITATIONAL PULL SO STRONG NOT EVEN LIGHT CAN ESCAPE
Black holes are so dense and their gravitational pull is so strong that no form of radiation can escape them – not even light.
They act as intense sources of gravity which hoover up dust and gas around them. Their intense gravitational pull is thought to be what stars in galaxies orbit around.
How they are formed is still poorly understood. Astronomers believe they may form when a large cloud of gas up to 100,000 times bigger than the sun, collapses into a black hole.
Many of these black hole seeds then merge to form much larger supermassive black holes, which are found at the centre of every known massive galaxy.
Alternatively, a supermassive black hole seed could come from a giant star, about 100 times the sun’s mass, that ultimately forms into a black hole after it runs out of fuel and collapses.
When these giant stars die, they also go ‘supernova’, a huge explosion that expels the matter from the outer layers of the star into deep space.