Pulsar-like White Dwarf


Here’s a bit of unexpected news posted on the Universe Today:

Observations of a white dwarf star (stellar remnant made up of degenerate matter and about the size of a terrestrial planet) indicate that it is showing the same form of highly bi-directional radiation that we commonly see in the much smaller and much denser pulsar variant of a neutron star:

“Some white dwarfs, including AE Aquarii, spin very rapidly and have magnetic fields millions of times stronger than Earth’s. These characteristics give them the energy to generate cosmic rays. But the Suzaku observatory also detected sharp pulses of hard X-rays. After analyzing the data, the astronomy team realized that the hard X-ray pulses match the white dwarf’s spin period of once every 33 seconds.

The hard X-ray pulsations are very similar to those of the pulsar in the center of the Crab Nebula. In both objects, the pulses appear like a lighthouse beam, and a rotating magnetic field is thought to be controlling the beam. Astronomers think that the extremely powerful magnetic fields are trapping charged particles and then flinging them outward at near-light speed. When the particles interact with the magnetic field, they radiate X-rays.

‘We’re seeing behavior like the pulsar in the Crab Nebula, but we’re seeing it in a white dwarf,’ says Koji Mukai of NASA Goddard Space Flight Center in Greenbelt, Md. The Crab Nebula is the shattered remnant of a massive star that ended its life in a supernova explosion. ‘This is the first time such pulsar-like behavior has ever been observed in a white dwarf.'”

I suppose it’s not completely surprising, but it is unexpected. And interesting because it gives another mechanism for the creation of cosmic rays. Which may in turn lower our estimates of the populations of other sources.

Read the rest here.

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Episcopal bishop, dad, astronomer, erstwhile dancer...