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Re: (meteorobs) Perseid stream spread (was: NAMN Notes: July 1999)
In a message dated 99-07-13 20:22:36 EDT, you write:
lew>> Wayne makes the point (I think) that there are a number of other
radiants
which are much larger, even based on true radar and photographic studies!
However, many of those are Ecliptic radiants, subject to a wide variety of
well-understood perturbations, and some actually represent more radiant
"complexes" than true single-stream radiants.<<
I don't have the radiant diameters for all the showers, just what I listed.
But of those, the North and South Taurids are Ecliptic radiants. The North
Taurid radiant diameter is 1.94 deg and the South Taurid radiant diameter is
2.20 deg. Both are quite small really. I couldn't say for sure, but I
wouldn't be a bit surprised that other ecliptic radiants such as
delta-cancrids, Virginids, Sagittarids, N. Iota Aquarids, Piscids and
chi-Orionids are also actually small also.
lew>> Last I looked though, Perseus was pretty far off the Ecliptic! ;> So my
question is, "Why is the Perseid radiant so large in diameter"?<<
There are two components to the Perseid radiant. One is tight and the other
is quite broad. Probably the main(tight) component of the Perseid radiant is
what has been measured to be around 1.26 deg. Compared to the other known
radiant diameters of other showers listed, it would seem that the Perseids
would be right up there in the pack. However, the broad component that lasts
for several weeks probably came about from a long period of planetary
perturbations and effects from the solar wind. The Perseid radiant is a
relatively old stream that has had plenty of time to distribute it's
particles.
GeoZay
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