Slow-motion neutron star challenges theoretical predictions

In this artist’s impression, the actual radio pulses detected from the slowest-spinning pulsar yet detected are visualized making their way from the source in Cassiopeia to the LOFAR radio telescope. Image: Danielle Futselaar and ASTRON

Using the Low-Frequency Array – LOFAR – radio telescope, astronomers have found the slowest spinning radio pulsar yet discovered, a highly magnetised neutron star that takes 23.5 seconds to complete one revolution. The fastest-spinning pulsar rotates once every 1.4 milliseconds while the slowest previously known pulsar has a period of 8.5 seconds.

“It is incredible to think that this pulsar spins more than 15.000 times more slowly than the fastest spinning pulsar known.” said Chia Min Tan, a PhD Student at the University of Manchester who discovered the pulsar. “We hope that there are more to be found with LOFAR.”

Neutron stars are the compact cores of once massive suns that ran out of nuclear fuel, collapsed and exploded in supernova blasts. Spinning neutron stars some 20 kilometres (12 miles or so) across are known as pulsars, which generate electromagnetic beams that shoot out into space from the poles. Depending on their orientation, these beams can be detected on Earth.

The slow-motion pulsar was found during LOFAR’s Tied-Array All-Sky Survey. Searching for pulsars in the northern sky, each survey “snapshot” of the sky lasts for a full hour, much longer than previous surveys.

“This pulsar spins so remarkably slowly that we could see it blinking on and off in our LOFAR radio images,” said Cees Bassa, co-author of a paper written for the Astrophysical Journal. “With faster pulsars that’s not possible.”

The researchers are pressing ahead with the LOFAR survey and plan to use the XMM-Newton space telescope to look for X-ray emissions from the slow-spinning pulsar.