'We Don't Planet' Episode 16: Pulsars

Neutron stars are some of the most exotic objects in the universe. The leftover cores of long-dead massive stars, they are macroscopic objects with densities of atomic nuclei. The gravitational pull at the surface is so intense that “mountains” are barely centimeters high, and a fall from that height would reach a terminal velocity of tens of thousands of miles per hour.

Though they are composed almost entirely of neutrons, there are protons scattered within the interior. Neutron stars also spin incredibly rapidly, a natural consequence of the conservation of angular momentum as the much larger progenitor star collapsed to much smaller volumes. The remaining electrical charge generated by the surviving protons, combined with the fast rotation, produces tremendous magnetic fields.

The magnetic fields are peculiarly strong; indeed they are the most powerful known magnetic systems in the universe , clocking in at an easy trillion times stronger than the Earth’s own field. At a distance of 620 miles (1,000 kilometers), the magnetic fields are strong enough to disrupt molecular bonds and reshape atoms themselves.

The magnetic field is constantly changing, which produces an electric field, which goes on to generate a new changing magnetic field. The end result of this interplay is a beam of radiation escaping the magnetic poles of the neutron star. If the magnetic poles aren’t aligned with the axis of rotation (like what occurs on the Earth), the beam of radiation sweeps a circular pattern into deep space.

If the beam flashes over the Earth, we can detect a pulse of radio emission with every rotation — hence the name “pulsars .”

“We Don’t Planet” is hosted by Ohio State University astrophysicist and COSI chief scientist Paul Sutter  with undergraduate student Anna Voelker. Produced by Doug Dangler, ASC Technology Services . Supported by The Ohio State University Department of Astronomy  and Center for Cosmology and AstroParticle Physics . You can follow Paul on Twitter  and Facebook .

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