As material from the large, low-mass star is pulled into a hot accretion disk swirling around its companion and interacts with its magnetic field, powerful x-rays are emitted, detectable as a “low-mass binary” by x-ray-sensitive telescopes like NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton.
But as the neutron star absorbs material from the spinning accretion disk it gains momentum, spinning faster and faster and ramping-up its magnetic field even further. As the flow of material from the low-mass star slows, the neutron star — now spinning madly, up to 254 times a second — throws much of the material in the disk out of the system entirely. With the x-ray emitting material gone, the neutron star is free to blast jets of radio waves out into space from its poles. It’s now a millisecond pulsar, and to anything aligned with its poles it flashes in radio like a lighthouse beacon on overdrive.
Talk about dancing with the stars.
While the full transition of a low-mass x-ray binary to millisecond pulsar is a process that’s thought to take place over billions of years, IGR J18245-2452 has given astronomers evidence that switches — in both directions — can occur much more rapidly… within a period of just a few days, in fact.
It’s the first time that the transition between these particular two stages of stellar evolution has been directly observed.
“We’ve been fortunate enough to see all stages of this process, with a range of ground and space telescopes. We’ve been looking for such evidence for more than a decade,” said Dr. Alessandro Papitto, lead author of the paper published in the Sept. 26, 2013 issue of Nature.
“It’s like a teenager who switches between acting like a child and acting like an adult,” said John Sarkissian, a co-author who observed the system with CSIRO’s Parkes radio telescope in Australia.
Read more at Discovery News
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