dietz%usc-cse%USC-ECL%SRI-NIC@sri-unix.UUCP (10/21/83)
Last year the pulsar PSR 1937+214 was discovered. It has a period of 1.5578 milliseconds (642 rps); its equator moves at 20% of the speed of light! The November Astronomy magazine has a piece on proposed theories for the origin of the pulsar. The object appears to have a very small magnetic field, is not associated with a supernova remnant and is spinning down very slowly. These would be the signs of an old pulsar -- except it spins much too fast! In addition it appears to be alone (not a member of a multiple star system). If it were in a multiple star system its motion could be detected by changes in the arrival times of its pulses. Earlier theories involved a pulsar forming in a binary system; the pulsar would then spin down and lose its magnetic field; then, its companion would expand and matter would accrete onto the pulsar, spinning it up again. The companion would then itself explode, disrupting the system. Unfortunately the numbers don't come out correctly; the companion would have to be so heavy it would supernova too quickly to spin up the pulsar. The new theory is this: the system was originally a binary system with two similar large stars. They supernovaed near the same time, forming two close neutron stars. If the stars are close enough the orbit will decay by the emmision of gravitational radiation. At least one such system is known today; the orbits are indeed decaying at precisely the rate predicted by general relativity. After some time (hundreds of millions of years) the two neutron stars will be orbiting each other almost in contact with a period of about one millisecond. Tidal forces then destroy the smaller star, transfering matter to the larger one. At some point the smaller neutron star is too small to remain a neutron star: it reverts to normal electronic matter and torn apart. Theory predicts the remaining star emits gravity waves until its period is about 1.5 milliseconds, which is nicely confirmed by observation.
METH%USC-ISI@sri-unix.UUCP (10/23/83)
That's the THIRD identical copy of the same message! Is there any way we (you) can filter out duplicate messages? Having to scan through a several-thousand character message is tedious, especially since there is no apparent way to kill that message without losing all the others on the Space Digest. -Sheldon Meth -------