Prediction of the 2009 Leonids by J. Vaubaillon (IMCCE)Introduction:For a general introduction to meteors see this page
The previous predictions posted earlier on on this page did not mention the presence of 2 Leonid trail in the vicinity of the Earth in Nov. 2009. There are indeed the 1466 trail and the 1533 each causing an outburst at roughly the same time (Nov. 17/11/2009 at 21:50 UT). In addition, the 1567 trail might cause a slight enhancement of activity on 17/11/2009 at 7:27 UT Below are the details for each trail. [url=]The situation in 2008[/url]Given the result of the 2008 Leonids campaign we can re-consider the predictions of the 2009 Leonids caused by the 1466 trail. The revised post-prediction for 2008 were the following:
| Year | 2008 | | TraiL | 1466 | | Nrev | 16 | | Time of max: | 17/11/2008 at 0:54 (UT) | | Sol.Long. | 234.9233 deg | | dist (au) | 0.003683 | | DeltaA (au) | 0.07617 | | f_M | 0.377 | | ZHR | 130 /hr |
Observations show that the maximum occured ~1hr later than expected, meaning that the trail was not located where we thought it was. The ZHR was close to what was forecasted. Note the high f_M value, coming from the perturbations of the planets, and Jupiter in particular.
The Situation in 2009The general location of the streams is illustrated below
A closer view is provided below. As can be seen there is an encounter with the 1466 and 1533 trails on Nov 17th.
Detailed Results1466 TrailThe situation for 2009 is the following:
The exact same trail (1466) as in 2008 will be encountered in Nov 2009. The forecastings are the following:
| Year | 2009 | | TraiL | 1466 | | Nrev | 16 | | Time of max: | 17/11/2009 at 21:43 UT (may be 0.5-1hr later) | | Sol.Long. | 235.54461 deg (idem) | | dist (au) | -0.000447 | | DeltaA (au) | 0.09939 | | f_M | 0.195 | | ZHR | 115 /hr |
f_M is less than in 2008 but the trail will be much closer to the Earth, explaining why we expect a quite high ZHR. Initially our expectations were much higher though (Vaubaillon et al 2005b). The recent analysis is based on the revised version of our program, taking into account the observations in 2008. In particular, the time of maximum may be later than expected, as in 2008. The work by E. Lyytinen and M. Nissinen (WGN, 37:4, Aug 2009, 122-124) also predicts a shower at this time and this level of activity. This plus recent changes in our code motivated us to completely re-do the Leonids forecastings, hence the change since last year. However the discrepancy between the expected time of maximum remains, as well as a general higher expected ZHR. Among the possible explanations are: sensitivity to initial conditions (given that the trail is 16 Rev. old) or change of cometary activity (impossible to verify unfortunately).
1533 TrailThis trail will encounter the Earth at almost the same time as the 1466 trail
The circumstances of the encounter are the following:
| Year | 2009 | | TraiL | 1533 | | Nrev | 14 | | Time of max: | 17/11/2009 at 21:50 UT | | Sol.Long. | 235.54952 deg | | dist (au) | 0.000533 | | DeltaA (au) | 0.13093 | | f_M | 0.114 | | ZHR | 80 /hr |
So the 2 trails will peak together for a total ZHR ~ 200/hr
1567 TrailThis one will pass further away from the Earth but may produce a noticeable activity
| Year | 2009 | | TraiL | 1567 | | Nrev | 13 | | Time of max: | 17/11/2009 at 7:27 UT | | Sol.Long. | 234.94546 deg | | dist (au) | -0.002026 | | DeltaA (au) | 0.12168 | | f_M | 0.065 | | ZHR | 25 /hr |
ConclusionThe year 2009 will not see a Leonid storm, but an outburst for sure. There are still some uncertainties regarding the time of maximum of the 1466 trail [Nov. 17th 2009, 21:43 UT (+1hr?)]. The total level of the shower (ZHR~200/hr) was callibrated using the 2008 observations of the 1466 trail, but nothing is known from the 1533 trail. As a consequence, it will be very interesting to check: The time of maximum of each trail. In particular there might be a difference of up to 1hr between the 1466 and 1533 trail, or they might even be late together, giving us some insight about how well/poorly we know comet 55P's orbit The duration of the shower, for the same reason as above: the 2 trails might be shifted, or not, wrt one another. The apparition of the outburst caused by the 1567 trail, if any: this will tell us about our limits of detection/prediction The orbit of the particles, in orer to make the difference between each trail. This is a tricky one, so any data is welcome (contact IMO) The location of the radiant(s), for the same reason.
The predictions for the position of the radiants from the diffferent trails are: For the 1466 trail:
And for 1533:
In theory it should be possible to distinguish between the 2 radiants. In practice it may be tricky. Observations are encouraged in order to differenciate the 2 trails.
Our colleagues from MSFC (D. Moser and B. Cooke) pointed out that the best location to view the outburst caused by the 1466 and 1533 trails will be centered around India and includes: Nepal, Thailand, Western China, Tadjikistan, Afghanistan, Eastern Iran, South Central Russia etc. |
|
置顶卡
变色卡
千斤顶
显身卡
