5 days ago
Friday, March 7, 2008
Neutron stars and magnetars
Considering my PhD research, I can appreciate the importance of statistics, so when there are only 12 of something - in this case, magnetars - which have been discovered in the entire universe, I can understand why a possible thirteenth is an amazing discovery (a free article may be found here).
Neutron stars, objects so dense that they basically can't get any more so (they are supported merely by degenerate neutron pressure), exist throughout the universe. They are typically the remnants of supernovae explosions, a tiny, rapidly spinning core where a giant once stood. Pulsars specifically are those which, by their quick rotation, produce a telltale EM radiation of rapid, regular pulses (typically in the radio frequency range). Magnetars are theorized to be neutron stars with such strong magnetic fields that "the magnetic field actually slows the star's rotation and causes starquakes that pump enough energy into the surrounding gases to generate bursts of soft gamma radiation" (NASA) that exceed, in fractions of a second, the energy output of the sun in a thousand years. They are so rare that the first was not discovered until 1979, and only twelve are known, though millions to hundreds of millions could exist.
The discovery of a possible "evolutionary step" between normal (in, of course, a funny context) neutron stars, pulsars and magnetars is therefore a momentous one. Perhaps, since this intermediate form seems to have a strong magnetic field, but not quite as strong as the twelve known magnetars, there is some mechanism by which the magnetic field strength grows throughout the neutron star's lifetime. Perhaps all magnetars begin as pulsars, or perhaps they evolve completely separately, but to differing degrees.
Perhaps, since my research deals instead with novae and x-ray bursts, I should get back to work.
Gavriil, F.P., Gonzalez, M.E., Gotthelf, E.V., Kaspi, V.M., Livingstone, M.A., Woods, P.M. (2008). Magnetar-like Emission from the Young Pulsar in Kes 75. Science DOI: 10.1126/science.1153465