Feeds

Boffins bend space and time to measure neutron star

Einstein shouts 'told you so', through tear in space-time

High performance access to file storage

Astronomers have caught three neutron stars in the act of distorting space-time, just as Einstein predicted. Bendy space-time has been seen around black holes before, but this is the first time astronomers have seen it around any other body.

Sudip Bhattacharyya and Tod Strohmayer, both of NASA’s Goddard Space Flight Center, turned the XMM-Newton observatory to a binary system called Serpens-1, whose neutron star has a disc of hot iron atoms whirling around just above its surface at around 40 per cent of the speed of light.

Artist's concept of a rare explosion on a neutron star. Credit: NASA/Dana Berry

The NASA team studied the line these atoms produce in the emission spectrum it produces, and discovered that the line is not clean, but smudged asymmetrically by a combination of its relativistic velocity and the effect of the neutron star's powerful gravitational field.

"We have seen these asymmetric lines from many black holes, but this is the first confirmation that neutron stars can produce them as well. It shows that the way neutron stars accrete matter is not very different from that of black holes, and gives us a new tool to probe Einstein’s theory," says Strohmayer.

A neutron star has such a strong gravitational field because, as the name suggests, it is formed entirely of neutrons. One is formed when a star of more than 8 times the sun's mass exhausts its supply of hydrogen and helium, and starts to burn heavier and heavier atoms, until all that is left is its iron core.

When it runs out of fuel, the weight of the star is such that it collapses inwards, fusing the protons and electrons in the iron to form neutrons. The star has now effectively become a truly gigantic atomic nucleus. It holds roughly one and a half times the matter as our own sun, but crammed into a sphere of just a 20 - 30km radius. It is so dense, a cupful would weigh the same as Mount Everest.

The pair of scientists has already confirmed their work with another research group. Working in a group led by Edward Cackett and Jon Miller of the University of Michigan, they used Suzaku’s superb spectral capabilities to survey three neutron-star binaries: Serpens X-1, GX 349+2, and 4U 1820-30.

The Suzaku data revealed a nearly identical iron line in Serpens-1, and similarly skewed lines in the other two binaries.

This team observed a nearly identical iron line in Serpens X-1, confirming the XMM-Newton result. It detected similarly skewed iron lines in the other two systems as well.

Cackett explains that the work has given researchers another tool to deploy in their study of the stars.

"We’re seeing the gas whipping around just outside the neutron star’s surface. And since the inner part of the disc obviously cannot orbit any closer than the neutron star’s surface, these measurements give us a maximum size of the neutron star’s diameter," he says.

"The neutron stars can be no larger than 29 to 33 km across, results that agree with other types of measurements." ®

High performance access to file storage

More from The Register

next story
Fancy joining Reg hack on quid-a-day challenge?
Recruiting now for charity starvation diet
Red-faced LOHAN team 'fesses up in blown SPEARS fuse fiasco
Standing in the corner, big pointy 'D' hats
KILLER SPONGES menacing California coastline
Surfers are safe, crustaceans less so
Opportunity selfie: Martian winds have given the spunky ol' rover a spring cleaning
Power levels up 70 per cent as the rover keeps on truckin'
Discovery time for 200m WONDER MATERIALS shaved from 4 MILLENNIA... to 4 years
Alloy, Alloy: Boffins in speed-classification breakthrough
Elon Musk's LEAKY THRUSTER gas stalls Space Station supply run
Helium seeps from Falcon 9 first stage, delays new legs for NASA robonaut
Top Secret US payload launched into space successfully
Clandestine NRO spacecraft sets off on its unknown mission
prev story

Whitepapers

Top three mobile application threats
Learn about three of the top mobile application security threats facing businesses today and recommendations on how to mitigate the risk.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.