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'Bent time' tips pulsar out of view | 'Bent time' tips pulsar out of view |
(less than a minute earlier) | |
A pulsar, one of deep space’s spinning “lighthouses”, has faded from view because a warp in space-time tilted its beams away from Earth. | A pulsar, one of deep space’s spinning “lighthouses”, has faded from view because a warp in space-time tilted its beams away from Earth. |
The tiny, heavy pulsar is locked in a fiercely tight orbit with another star. | The tiny, heavy pulsar is locked in a fiercely tight orbit with another star. |
The gravity between them is so extreme that it is thought to emit waves and to bend space - making the pulsar wobble. | The gravity between them is so extreme that it is thought to emit waves and to bend space - making the pulsar wobble. |
By tracking its motion closely for five years, astronomers determined the pulsar’s weight and also quantified the gravitational disturbance. | By tracking its motion closely for five years, astronomers determined the pulsar’s weight and also quantified the gravitational disturbance. |
Then, the pulsar vanished. Its wheeling beams of radio waves now pass us by, and the researchers have calculated that this can be explained by “precession”: the dying star wobbling into the dip in space-time that its own orbit created. | Then, the pulsar vanished. Its wheeling beams of radio waves now pass us by, and the researchers have calculated that this can be explained by “precession”: the dying star wobbling into the dip in space-time that its own orbit created. |
Their findings are published in The Astrophysical Journal and were presented at the 225th meeting of the American Astronomical Society. | Their findings are published in The Astrophysical Journal and were presented at the 225th meeting of the American Astronomical Society. |
‘Eureka moment’ | ‘Eureka moment’ |
A pulsar is a small but improbably dense neutron star - the collapsed remnant of a supernova. | A pulsar is a small but improbably dense neutron star - the collapsed remnant of a supernova. |
“They pack more mass than our Sun has in a sphere that’s only 10 miles across,” said the study’s lead author Joeri van Leeuwen, from the Netherlands Institute for Radio Astronomy (Astron). | “They pack more mass than our Sun has in a sphere that’s only 10 miles across,” said the study’s lead author Joeri van Leeuwen, from the Netherlands Institute for Radio Astronomy (Astron). |
When they occur as binaries, neutron stars come hard up against Einstein’s theory of general relativity, and should generate space-time ripples called gravitational waves, which astronomers hope one day to detect. | When they occur as binaries, neutron stars come hard up against Einstein’s theory of general relativity, and should generate space-time ripples called gravitational waves, which astronomers hope one day to detect. |
This particular specimen, Pulsar J1906, popped up unexpectedly during a survey Dr van Leeuwen and colleagues were conducting at the Arecibo Observatory, Puerto Rico. | This particular specimen, Pulsar J1906, popped up unexpectedly during a survey Dr van Leeuwen and colleagues were conducting at the Arecibo Observatory, Puerto Rico. |
“That was a real Eureka moment that night,” he told journalists at the conference. | “That was a real Eureka moment that night,” he told journalists at the conference. |
“It was strange, because that part of the sky's been surveyed lots of times - and then something really bright and new appears.” | “It was strange, because that part of the sky's been surveyed lots of times - and then something really bright and new appears.” |
They soon discovered the pulsar had a companion star, and that it was pushing the boundaries of what astronomers know of these bizarre systems. | They soon discovered the pulsar had a companion star, and that it was pushing the boundaries of what astronomers know of these bizarre systems. |
The pair circle each other in just four hours - the second fastest such orbit ever seen - and the pulsar spins seven times per second, sweeping its two beams of radio waves across space to Earth. | The pair circle each other in just four hours - the second fastest such orbit ever seen - and the pulsar spins seven times per second, sweeping its two beams of radio waves across space to Earth. |
Drifting axis | Drifting axis |
Dr van Leeuwen’s team set about monitoring those waves, nearly every day for the next five years, using the world’s five biggest radio telescopes. | Dr van Leeuwen’s team set about monitoring those waves, nearly every day for the next five years, using the world’s five biggest radio telescopes. |
All told, they clocked one billion rotations of the pulsar. | All told, they clocked one billion rotations of the pulsar. |
“By precisely tracking the motion of the pulsar, we were able to measure the gravitational interaction between the two highly compact stars with extreme accuracy,” said co-author Prof Ingrid Stairs of the University of British Columbia, Canada. | “By precisely tracking the motion of the pulsar, we were able to measure the gravitational interaction between the two highly compact stars with extreme accuracy,” said co-author Prof Ingrid Stairs of the University of British Columbia, Canada. |
Each is approximately 1.3 times heavier than our Sun, but they are only separated by about one solar diameter.“The resulting extreme gravity causes many remarkable effects,” Prof Stairs said. | Each is approximately 1.3 times heavier than our Sun, but they are only separated by about one solar diameter.“The resulting extreme gravity causes many remarkable effects,” Prof Stairs said. |
Chief among those is the time-space warp and the wobble that has now caused J1906 to shine its light elsewhere - for the time being. | Chief among those is the time-space warp and the wobble that has now caused J1906 to shine its light elsewhere - for the time being. |
The pulsar’s axis drifts by two degrees every year, and according to Dr van Leeuwen’s calculations it should swing back around to shine on Earth again by about 2170. | The pulsar’s axis drifts by two degrees every year, and according to Dr van Leeuwen’s calculations it should swing back around to shine on Earth again by about 2170. |
Gravity lab | Gravity lab |
Prof Tim O'Brien is an astrophysicist working at the University of Manchester and the Jodrell Bank Observatory in the UK - one of the facilities that helped track the pulsar. | Prof Tim O'Brien is an astrophysicist working at the University of Manchester and the Jodrell Bank Observatory in the UK - one of the facilities that helped track the pulsar. |
He was not involved in the research, but told BBC News he had watched the project develop with interest. | He was not involved in the research, but told BBC News he had watched the project develop with interest. |
"It's a pretty unusual object," he said, adding that tracking it in such detail had been a "big campaign". | "It's a pretty unusual object," he said, adding that tracking it in such detail had been a "big campaign". |
"Using these five telescopes all around the world, they effectively accounted for every single one of the billion rotations over five years. | "Using these five telescopes all around the world, they effectively accounted for every single one of the billion rotations over five years. |
"It's incredible that you can measure all these parameters with such precision. | "It's incredible that you can measure all these parameters with such precision. |
"These systems are amazing natural laboratories for studying gravity. We were very lucky to catch it for that particular period." | "These systems are amazing natural laboratories for studying gravity. We were very lucky to catch it for that particular period." |
Party of five: The biggest radio telescopes on Earth | Party of five: The biggest radio telescopes on Earth |
Follow Jonathan on Twitter | Follow Jonathan on Twitter |