pulsars, white dwarf stars, and clocks (short)

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2 total messages Started by Ethan Vishniac Sat, 19 May 1984 21:31

#26

Author: Ethan Vishniac
Date: Sat, 19 May 1984 21:31

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[BACK IGOR!!!!!]

Ed is right.
Clocks are nice, but I don't think that white dwarf pulsations can
have such *short* periods.  This is the crucial point in deciding
that pulsars must be neutron stars.  

"Cute signoffs are for weirdos"    Ethan Vishniac
                                   {kpno,charm,ut-sally}!utastro!ethan

Sol's dark sister?

#28

Author: Randy Haskins
Date: Tue, 22 May 1984 00:11

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In the Boston Globe today (Monday 21 May), there was a small article
that will supposedly be written about 14 million years from now about
the impending return of "Nemesis."  This is supposedly a dark dwarf star
that orbits our Sun with a period of approximately 26 M years.  (doing
math, you see that it last appeared about 12 M years ago, and that it
also appeared around the time (~ 65 M years ago) that the dinosaurs
disappeared, and that it is within 1M years of apohelion.)  The dwarf
supposedly has a large contingent of comets, some of which will hit the
earth and cause devastation.

Doing a quick and dirty calculation, IF the comet had a near-circular
orbit (which it obviously doesn't but I just wanted to get within a
couple orders of magnitude), I come up with 87k A.U.'s (about
1.3 light years), contrasted with about 17 A.U.'s for Halley's comet,
as a mean orbital distance.  I would think that's quite a distance for
it not to be affected by other stars (since it's probably swinging
out between 10 and 100 times that far, the article doesn't say
much in the way of real science, like its eccentricity, its
perihelion distance, etc.). 

Anyway...  I was wondering how come I never hear-tell of this before.
Is this a recent discovery?  Is it something that a lot of
you experts think is bogus?  I'd be interested in hearing what
is known about this so far.

-- 
Randwulf  (Randy Haskins);  Path= genrad!mit-eddie!rh

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