(meteorobs) Leonids 2011-2020

[Mikhail Maslov]

Hello.
I wish to introduce the results of Leonids meteor stream
simulation. It is the analysis of possibilities and conditions of
Earth encounters with trails of the periondic comet 55P in years
2011-2020. The modelling was made for the trails of latest 12
revolutions, i.e, from the 1600 trail. I used the program by S. Shanov
and S. Dubrovsky to calculate orbital elements of ejected meteor
particles. To estimate expected ZHRs for different encounters I used
the model by E. Lyytinen and T. van Flandern, given in their paper
"Predicting the strength of Leonid outbursts" with some my
alterations, made in order to adopt the model for ejection velocity
(v) instead of da0 (difference in a-semimajor axis) as well as to correct
fn function to consider factual Leonids activity during recent storms
and outbursts. The calculation considers only gravitational forces,
however, the results are on the whole in good accordance with ones of
other researchers and the reality.
I included in the forecast all encouners found within interval +/-0.007
a.u. The following trail parts were analised: the first 5 rev. trails
for ejection velocities [-50;100] m/s, 6-10 rev. trails - [-25;50]
m/s, older than 10 rev. trails - [-10;25] m/s.

In a whole, as it should be expected, no sufficient encounters are not
found. However, some cases worth some attention:
- In 2011 a moderate approach of several dense parts of 1800 trail
will happen. This situaltion is very similar to 2009 case, but ZHRex
from all the three encounters is not greater than 3-4. Also, as in
2009, the maximum time is notably earlier than general maximum.
So there are some chances that the trails will show itsetf somehow,
especially if its real activity would be higher than expected.
- 2019. In this year I expect very close approach of 4 rev. trail
(1866). Its part corresponds to ej.vel.=92.8 m/s and ZHRex=4. However,
as in 2006 and 2007 much stronger telescopic activity is possible.
- 2020. The most contradictory case. In this year the parts of trails
around 2031 perihelion with negative ej. velocities will start to
approach. In 2020 the Earth will pass at considerable distance from
dense part of 7 rev trail (1800), corresponding to ej.vel.=-21 m/s.
When calculting ZHRex I used ej.vel.=+21 m/s and got ZHRex=10. Also,
if the distance would be zero, I'd got ZHRex=1650. It is believed,
that amount of particles ahead of a comet is much lower than behind
it. Nevertheless, this result means that in principle strong Leonid
outbursts are possible in during the "quiet" period (in our case - at
11 years till perihelion). Also, result ZHRex=10 is most likely purely
nominal, real activity would be much lower if anything would happen.
However, I think some years of 2020s will be very important for
expanding fn function to the area of negative ejection velocities.
rev. Year  rd-re   ej. Vel. fM(fNP) sol.long max. Time   ZHR ex.
            AU       m/s              deg       UT
2011
6    1800 -0,00015  49,2    0,002   234,009 16.11.11 21:29  0 empty
6    1800 -0,00032  49,1   -0,039   234,009 16.11.11 21:34  1
6    1800 -0,00348  47,3    1,245   234,040 16.11.11 22:17  3
6    1800 -0,00419  46,7   -0,457   234,047 16.11.11 22:28  1
6    1800 -0,00459  46,7    0,003   234,051 16.11.11 22:33  0 empty
2012
5    1833 -0,00658  50,0    0,427   234,655 16.11.12 19:04  0
2013
5    1833 -0,00342  56,7    0,240   234,983 17.11.13 9:02   0
2014
5    1833 -0,00218  60,9    0,207   234,885 17.11.14 12:52  1
2015
4    1866 -0,00472  66,8    0,333   234,773 17.11.15 16:21  0
2016
8    1733 -0,00060  47,2    0,000   247,494 29.11.17 12:28  0 empty
2017
4    1866 -0,00290  80,1    0,047   234,573 16.11.17 23:55  0
5    1833  0,00568  78,5    0,045   234,303 16.11.17 17:28  0
2018
5    1833  0,00337  86,1    0,001   236,139 18.11.18 19:20  0 empty
2019
4    1866 -0,00193  91,2   -0,002   234,475 17.11.19 9:53   0 empty
4    1866 -0,00028  92,8    0,359   234,631 17.11.19 13:35  4
4    1866 -0,00210  91,2    0,001   234,633 17.11.19 13:37  0 empty
5    1833 -0,00175  89,0    0,150   235,888 18.11.19 19:30  1
5    1833 -0,00153  89,7   -0,040   235,895 18.11.19 19:40  0
5    1833 -0,00152  89,9    0,006   235,896 18.11.19 19:42  0 empty
2020
5    1833 -0,00209  91,7    0,225   235,683 17.11.20 20:47  1
4    1866  0,00204  91,7    0,000   235,787 17.11.20 23:15  0 empty
7    1800  0,00575 -21,0    0,295   236,830 19.11.20 0:04   10

Best regards, Mikhail Maslov