Leonids 2019: prediction of activity
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Fig. 1. Space-temporal projection of Leonids trails parts onto their minimal distance passages in 2019 (correspondence between colours of the particles and their ejection velocities can be seen here).
Fig. 3. Assumed profile of overall Leonid activity (blue line) and its background component (red line).
As seen on the Fig. 2, in 2019 some outbursts are possible in addition to the background maximum. The first of them has quite prominent peak with expected ZHR=27, it is connected with 1400 trail, its computed maximum time is at 2:35 UT on 16 November, which is a day before the background maximum. However the reliablity of this ouburst predition is quite low, as the Earth enconters the part of 1400 trail composed of particles with negative ejection velocities (around -16 m/s). Such trails parts are depleted with particles as smaller of them are blown out by radiation pressure. Nevertheless we suggest that some remaining larger particles could pruduce a notable activity enhancement with high share of bright meteors.
The background maximum itself will interlapse with a number of small outbursts from trails. For instance, at 13:35 UT on 17 November a small enhancement is possible with ZHR=6-7 above the background (total ZHR=19). Prediction of this enhancement is much more reliable as it is caused by encounter with 1866 trail composed of particles with positive, though very high (93 m/s) ejection velocities. It means small sizes of particles, so faint meteor share could increase at the given maximum time. Also the number of radiometeors could significantly increase.
The third small activity enhanced is visible on the Fig. 2 after the background maximum, its computed peaktime is 4:13 UT on 19 November, and its own ZHR=4 while together with background activity total ZHR=14. This enhancement is connected with 1800, but, as the first one, with particles ejected with high negative ejection velocity of -26 m/s, which makes the reliability of this enhancement prediction very low.
References
1. "Comet's dust 2.0" program by S. Shanov and S. Dubrovsky. [Used for orbital computations.]
2. Lyytinen E, van Flandern T. "Predicting the strength of Leonid outbursts", 2000, Icarus, P. 158-160.
3. Jenniskens P. Meteor showers and their parent comets, 2006, 780 p. 4. Kasuo Kinoshita, http://jcometobs.web.fc2.com/ [Orbital elements of the comet 55P Tempel-Tuttle]