In 1967 a PhD student named Jocelyn Bell detected a radio signal with an odd regularity. Patterns can be heard in all sorts of radio signals, but this particular signal was unusual in that it was a pulse with a period of 1.33 seconds. You can see this pattern in the figure above, and you can hear what the signal sounds like here.
Passing the Test
Recently popular-science websites have been buzzing with news of a new pulsar putting Einstein’s theory of gravity to its greatest test yet. In particular, some tout it as a test of alternatives to general relativity. While the attention this work has gotten in the press implies this is a new breakthrough, that’s not quite the case. So what’s the real deal on these latest findings?
Kick Me
Pulsars are neutron stars, formed when a large star explodes as a supernova. Because of this, one would expect a pulsar to lie within the surrounding supernova remnant, and to move at the same relative speed. But this is not the case with the Guitar Nebula. It seems that something must have caused the pulsar to move at great speed relative to the remnant. Given it a kick, as it were, hence the term pulsar kick (or neutron star kick). Given the mass of a neutron star (greater than that of our Sun) the only thing that could have provided such a kick would be the supernova itself.
Twinkle Twinkle Little Pulsar
Stars twinkle due to turbulence in our atmosphere. A similar effect occurs with pulsar signals, which twinkle due to turbulence in the Sun’s heliosphere.
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