Perseids 2009-2010: prediction of activity
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Introduction
Computation characteristics
We'd like to introduce the results of the Perseid meteor stream simulation aimed to the prediction of shower activity in 2009. The simulation was made for the trails of latest 7 revolutions, i.e, from the 1992 trail. The Author used the program by S. Shanov and S. Dubrovsky "Comet's Dust 2.0" to calculate orbital elements of ejected meteor particles. To estimate expected ZHRs for different encounters the model by E. Lyytinen and T. van Flandern given in their paper [4] was used with some Author's alterations made in order to adopt the model for ejection velocity (Vej) instead of da0 (difference in a-semimajor axis) and to convert the model from the Leonid stream (for which it was originally created) to the Perseids. The computation considered only gravitational forces, however, the results are on the whole in good accordance with these of other researchers. The prediction includes all encounters found within interval +/-0.007 a.u. The following parts of trails were computed: the first 5 rev. trails for ejection velocities [-50;100] m/s, 6-7 rev. trails - [-30;50] m/s.
Results
Introduction
Computation characteristics
We'd like to introduce the results of the Perseid meteor stream simulation aimed to the prediction of shower activity in 2009. The simulation was made for the trails of latest 7 revolutions, i.e, from the 1992 trail. The Author used the program by S. Shanov and S. Dubrovsky "Comet's Dust 2.0" to calculate orbital elements of ejected meteor particles. To estimate expected ZHRs for different encounters the model by E. Lyytinen and T. van Flandern given in their paper [4] was used with some Author's alterations made in order to adopt the model for ejection velocity (Vej) instead of da0 (difference in a-semimajor axis) and to convert the model from the Leonid stream (for which it was originally created) to the Perseids. The computation considered only gravitational forces, however, the results are on the whole in good accordance with these of other researchers. The prediction includes all encounters found within interval +/-0.007 a.u. The following parts of trails were computed: the first 5 rev. trails for ejection velocities [-50;100] m/s, 6-7 rev. trails - [-30;50] m/s.
Results
Fig. 1. Space-temporal projection of Perseids trails parts onto their minimal distance passages dirung the period 12.05.2009-12.11.2010 (correspondence between colours of the particles and their ejection velocities can be seen here).
Fig. 2. Detailed space-temporal projection of Perseids trails parts onto their minimal distance passages dirung the period 12.05.2009-12.11.2009 (correspondence between colours of the particles and their ejection velocities can be seen here).
Fig. 3. Detailed space-temporal projection of Perseids trails parts onto their minimal distance passages dirung the period 12.05.2010-12.11.2010 (correspondence between colours of the particles and their ejection velocities can be seen here).
2009
As shown on the Fig. 1 and 2, in 2009 Perseid maximum will occur when the Earth's orbit will be intersected by particles, strongly perturbed by Saturn. So far, the background part of the stream will be significantly closer to the Earth and we expect a strong increase of traditional Perseid maximum intensuty, appr. up to 200 meteors. Unfortunately, in 2009 Perseids will happen under moonlight, which severely decrease the impression from the activity. Also in 2009 will occur a number of encounters with 1872, 1737 and 1610 trails. The most interesting of them is the latter. The parameters of the enconters are given below:
| trail | rD-rE | Vej | fM(fMD) | SL | MT |
| - | AU | m/s | - | ° | UT |
| 1861 | -0.00335 | 31.32 | 0.079 | 139.478 | 12.08.2009 4:33 |
| 1737 | 0.00463 | 23.06 | 0.015 | 139.599 | 12.08.2009 7:35 |
| 1610 | 0.00094 | 11.82 | 0.005 | 139.621 | 12.08.2009 8:07 |
At given time 1610 trail can add 10-15 meteors on ZHR scale to the background activity. This should be detectable outburst. Also, average meteor brightness should increase around the peak. Observers are recommended to check this encounter.
It should be noted that many researchers point out probability of high Perseid activity in 2009, E. Lyytinen, I. Sato, J. Vaubaillon are aming them. They also describe the encounter with 1610 trail.
2010
You can see on the Figs. 1 and 3 that in 2010 the stream wave perturbed by Saturn will be over in large scale. Though, the stream will be still a bit closer to the Earth's orbit than in usual years, so we expect traditional maximum to be a little higher than usual, perhaps up to 110-120 meteors on ZHR scale.
Also on the Fig. 3 green lines connect particles of regular but very thin 1349 trail. This trail will be at 0.00098 AU from the Earth's orbit, its maximum time is 12.08.2010 19:23 UT. However, high ejection velocity (50.40 m/s) and very low density (fM(fMD)=-0.008) leave virtually no chances for any notable visual activity enhancements.
Also we should mention results of J. Vaubaillon and I. Sato for 2010, they found an encounter with 1479 trail. Maximum time from this trail is 16:39 UT on 12 August, according to Vaubaillon, and 14:06 UT on 12 August, as Sato's results say.
References
1. "Comet's dust 2.0" program by S. Shanov and S. Dubrovsky. [Used for orbital computations.]
2. Information from Gary W. Kronk's page http://www.maa.agleia.de
3. IMO Meteor Shower Calendar 2006 http://www.imo.net/calendar/russian/2006/spring.
4. Lyytinen E, van Flandern T. "Predicting the strength of Leonid outbursts", 2000, Icarus, P. 158-160.
5. Jenniskens P. Meteor showers and their parent comets, 2006, 780 p.