[time-nuts] nubie querie
Hal Murray
hmurray at megapathdsl.net
Fri Mar 5 18:14:10 UTC 2010
richard at karlquist.com said:
> I vaguely remember reading that pulsars have some fantastic stability
> like 1E-20. I don't remember how they established this.
Do you remember how long ago you read that? It might have been some
handwaving back before they had good data.
For a while, the astronomers were seriously trying to take back the official
clock from the physicists. They didn't make it. I think a lot of the
interest started when somebody discovered a pulsar ticking at close to 1 KHz.
That was in 1982.
They have collected enough data to see things like star-quakes which are
glitches in the rotation rate due to geologic type shifts similar to the
recent discussion of 1.26 microseconds per day from the Chile quake.
They decay by gravitational radiation and speed up when accretion adds more
momentum and energy.
Scientists predict pulsar starquakes
June 5, 2006
http://www.lanl.gov/news/index.php/fuseaction/home.story/story_id/8528
Middleditch and his team have discovered that for one particular pulsar,
named PSR J0537-6910, the time until the next quake is proportional to the
size of the last quake. Using this simple formula, the scientists have been
able to aim NASA's Rossi X-ray Timing Explorer at the pulsar a few days
before a quake to watch the event unfold.
[A fun read.]
--
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