Leonids 2006

by Mikiya Sato (for Jeremie Vaubaillon)

v0.1 : 2006/07/20

I calculated dust trails which will approach to the Earth in 2005.
In the trails which was ejected after 1733, only the trail from 1932 (2-revolution) will be approach.
And, in the trails which was ejected after 901, there is not a trail with good condition (in this case, I set ejection velocity between +20 and - 20m/s).

Table 1 Data of dust trail in 2006

Ejection
Year
Date
(UT)
Time
(UT)
Sol.Long.
(2000)
dR
(AU)
Ejection
Velocity(m/s)
fMR.A.Del.Vg
(km/s)
Note
19652006/11/18.9222:05236.335-0.013+150.771.0154.18+21.1871.15No peak
19322006/11/19.2004:44236.615+0.000096+88.260.62154.32+21.1070.80*Careful
18992006/11/22.7618:18240.216-0.011+58.690.081156.66+20.0971.08No peak

Table 1 shows the calculation results within 3-revolution.
About the trail of 1932, the approach distance(dR) is very close, as 0.00001 AU.
However, the ejection velocity was very large, as +88 m/s. In my calculation, an ejection velocity of Draconids (Giacobinids) in 1999 was so large, about +60 and +70 m/s (Sato 2003). But, the ejection velocity of trail in this year, from 1932, was larger than that of Draconids in 1999. Therefore, to predict this shower scale is very difficult for me. But it is easy to expect that a meteor magnitude will be very dark because the expected size of meteoroids is very small.

On the other hand, almost same part of this trail approached to the Earth in 1969.

Table 2 shows the situation of then. The trail from 1932 (1-revolution) approached very close.

Table 2 Data of dust trail in 1969

Ejection
Year
Date
(UT)
Time
(UT)
Sol.Long.
(2000)
dR
(AU)
Ejection
Velocity(m/s)
fMR.A.Del.Vg
(km/s)
Note
19321969/11/17.3708:58235.272+0.000054+85.96 1.0  153.50+21.6170.74Sharp peak
was observed

The approach distance (dR) was very close, and the ejection velocity was as high as that of 2006.

In that year, the sharp shower was observed in the eastern part of US (Sky and Telescope 1970). The shower was observed arround 9:00 UT on Nov. 17. Maximum hourly rate was about over 100, or over 200 (by only one report). The observed peak time coincided with a result of calculation. So, the shower would have been brought by this trail from 1932.

The fM value in 2006 was smaller than that in 1969 because of 2-revolution. Therefore, in 2006, it is expected that the hourly will be between 100 and 150.

Moreover, we must be careful predicting the meteor magnitude. In that article, there was such description as several meteors left trains lasting about eight seconds. As for this thing, it suggests the possibility that the bright meteor appear in this year, contrary to the expectation.


References