IMCCE Meteor Shower Ephemerides Server

2006 Leonids

Introduction:

Are the Leonids back? According to McNaught & Asher (1999), there should be an outburst of the Leonid meteor shower in 2006. Our first results (Vaubaillon, 2003, PhD Thesis) suggested that nothing particular was expected, so what the heck is going on here? Later on it was realized that the simulated particles were just too large to efficiently encounter the Earth in November 2006, given the way the simulations are performed (see: Vaubaillon et al. 2005a). It is clear now that the Leonids are back, but there will definitely NOT be a storm like in the year 1998-2002 (as already forecasted by McNaught & Asher, 1999).

Results

The following image provides an overview of the whole Leonid meteoroid stream in the vicinity of the Earth in November 2006. The line represents the path of the Earth and each cluster of dots represents a particular trail. As can be seen: at least one outburst is expected early on the 19th of Nov.

The following image is a zoom on the encounter with the 2 revolution old trail (ejected in 1932).

Though the encounter is obvious care must be taken when trying to deduce a visible ZHR. D. Asher as well as M. Sato pointed out that the encounter will be similar to the 1969 shower (see below the links to their web pages). We must stress that our value slightly differ from theirs, mainly because of the method used to perform the forceastings (Vaubaillon & Jenniskens, in preparation). We actually have: f_M=0.90, rE-rD=0.000884 au, delta_a=1.7642590 au, for a time of maximum occuring at 4:58 UT on 19/11/2006 (Sol.Long.=236.624). Such a high f_m value leads to a very high ZHR BUT the particles considered here are smaller than all previous forecastings! Therefore they are not visible by naked eye, but hopefully by radio devices. The visible ZHR should not exceed the 1969 value, and be around ~100, as already pointed out by McNaught & Asher, and Sato.

The following figure shows the nodes of the particles in the range [0.05-0.1]mm and [0.1-0.5]mm, as well as the radius of a function of days of ejection and the ejection velocity of the particles selected here. JJ=0 refers to the perihelion passage of the comet in 1932.
[0.05-0.1]mm

[0.1-0.5]mm

radius=f(JJ)

Vej=f(JJ)

It can be seen that the ejection velocity is of the order of 40-50 m/s and the particles are mostly in the range [0.05-0.1]mm, again arguing in favor of a radio outburst better than the visual one.

About the encounter with the 1366 trail (19 rev. old): peaking at 7:55 UT on 20/11/2006 (Sol.Long.=237.757 deg), the f_M value of 0.0093 kinda ruins any hope, but who knows?...
The 1366 trail (19 rev.)

Same for the 1201 trail (24 rev. old): f_M= 0.0540, max. at 1:24 UT on 21/11/2006 (Sol.Long.=238.493 deg)
The 1201 trail ((24 rev.)

IMCCE Meteor Shower Ephemerides Server

2006 Leonids

Introduction:

Results

See also