(meteorobs) Dust trail computations: Bielids and Giacobinids
Mikhail Maslov
ast0 at mail.ru
Tue May 16 23:02:08 EDT 2006
Hello, Joe and all,
I made computations for Draconids, so I can answer you question about
Draconids 2011. For Draconids 1933, 1946 and 2011 (and 1998) I got
the following figures:
Draconids 1933 (main encounters)
tr-l year rd-re Vej fM(fMD) sol.long max. Time ZHR ex.
AU m/s deg UT
4 1907 -0,00023 20,0 3,800 197,008 09.10.1933 20:11 1438
5 1900 -0,00013 15,1 2,996 197,014 09.10.1933 20:19 5514
where tr-l is the number of revolutions of given trail; year - the
year of trail formation; rd-re - the distance between the Earth's
orbit and trail particles orbit (positive value means the descending
node of trail is outside the Earth's orbit, negative - the node is
inside it); Vej - velocity particles ejection on the given trail part
(positive values means the particles were ejected against the comet
movement, negative - particles the ejected along the comet movement);
fM(fMD) - the characteristic of longitudinal density of a trail, it is
derived from the time interval between minimal distance to the Earth's
orbit passages of particles with different ejection velocities; sol.
long. - solar longitude corresponding the maximum; ZHR ex. - ZHR
expected to be produced by the trail.
Draconids 1946 (main encounters)
tr-l year rd-re Vej fM(fMD) sol.long max. Time ZHR ex.
AU m/s deg UT
1 1940 0,00113 13,90 13,602 196,982 10.10.1946 3:32 198
2 1933 0,00098 7,20 7,062 196,982 10.10.1946 3:32 75
3 1926 0,00090 4,90 6,181 196,982 10.10.1946 3:33 40
4 1920 0,00082 3,70 4,424 196,985 10.10.1946 3:37 23
5 1913 0,00054 3,20 3,299 196,992 10.10.1946 3:47 38
6 1907 -0,00004 3,00 3,191 197,005 10.10.1946 4:06 23748
7 1900 -0,00016 2,70 2,644 197,011 10.10.1946 4:14 502
Draconids 1998 (main encounters)
tr-l year rd-re Vej fM(fMD) sol.long max. Time ZHR ex.
AU m/s deg UT
11 1926 -0,00020 11,10 -2,629 195,085 08.10.1998 13:27 993
Draconids 2011 (main encounters)
tr-l year rd-re Vej fM(fMD) sol.long max. Time ZHR ex.
AU m/s deg UT
19 1887 -0,00092 1,50 -0,120 194,905 08.10.2011 17:04 0
18 1894 0,00107 2,20 -0,187 194,948 08.10.2011 18:06 8
17 1900 -0,00136 8,30 -0,767 195,035 08.10.2011 20:13 50
You can see the picture with distribution of 21P trails near the
Earth orbit in 2011 here: http://feraj.narod.ru/2011.gif
I should also mote, that in my opinion for Jupiter-family streams geometry
of trails is not less important that distances rd-re to individual
trails. I develop this idea in an article prepared for WGN. Here I
give an abstract from this it, discussing Draconids 2011:
"In 2011 the Earth will come close to rather compact channel of quite
old trails. The closest encounter will be with 1887, 1894 and 1900
trails, so they will be responsible for major part of Draconid
activity...
... the Author does not expect very strong Draconid activity
in 2011. Trails 1887 and 1894 are not dense, so their peaks will be
very minor, especially from 1887 trail. The majority of meteors will
be produced by 1900 trail. Due to lower ejection velocities of 1887
and 1894 trails particles the Author supposes this increasing part of
outburst will not be sharp with relatively high share of bright
meteors in the period 16-19 UT 8 October, then during 18-19 UT the
activity will continue rising but with decline of average meteor
brightness. Predictions of outburst intensity are though not very
certain due to the lack of observing data. It is expected that ZHRmax
will be most probably within 10-100 meteors. Decline in activity will
be more sharp, than its rise."
So far I expect not very strong but quite lenghy outburst, slow rising
in activity with brighter meteors and possible submaximas, then
declining average brigntness at maximum (around 20:10 UT 8 October)
and comparatively rapid decrease of activity).
Best regards, Mikhail Maslov
Sac> I know that dust trail predictions concerning the upcoming 2011
Sac> Giaconinids shower and 2022 73P/Schwassmann-Wachmann meteors have been issued in recent
Sac> years by several meteor experts who belong to this list.
Sac> I believe it would be most interesting if we were able to compare these
Sac> impending encounters with similar events from the past. Has any one looked at
Sac> the dust trail situation which resulted in the 1872 or 1885 Bielid Storms or
Sac> the 1933 and 1946 Giacobinid encounters? I would be especially interested in
Sac> making comparisions between values such as rE - rD (the heliocentric distances
Sac> of the dust trail node and of the Earth at the same longitude).
Sac> Have such computations been made?
Sac> And if so, where might they be available (either in tabular or graphic form)?
Sac> -- joe rao
Sac> ---
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