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Highly recycled pulsar discovered -- culprit unknown

Submitter: Joeri van Leeuwen
Description: In this week's edition of Science we report on the discovery of a speedy spinning pulsar in an elongated orbit around an apparent Sun-like star, a combination never seen before. It has us puzzled about how the strange system developed: as the Sun-like star cannot have spun up the pulsar to its current frequency it's unclear how the pulsar got to rotate this fast.

"The high-precision timing of this pulsar using Westerbork, Arecibo and the GBT has enabled us to reveal the unique properties of this system, such as the high mass and very elliptical orbit of the neutron star. The large mass will help us understand the properties of matter at densities so extreme they cannot be studied on Earth", Ben Stappers says.

The apparently most viable formation scenario suggests the pulsar may be part of a triple, not a double, star system. "In this case, the pulsar is in a close orbit around a dim white dwarf, and the Sun-like star is in a more-distant orbit around both the pulsar and its close companion", says Joeri van Leeuwen, who evaluated the likelihood such a system could survive. "We know of about 50 pulsars in binary systems so-far, but it appears we've now found the first pulsar in a stellar triple system."

In the image above we compare the size and ellipticity of the pulsar orbit with the Earth's orbit (stars, Earth and pulsar themselves not to scale).

Copyright: Bill Saxton (NRAO), Joeri van Leeuwen (ASTRON), Ben Stappers (UManchester)
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