The Draconids meteor shower come from Comet 21P/Giacobini-Zinner, and as such have often been called the Giacobinids in the past. The meteoroid stream ejected by the comet approaches the Earth on a regular basis, but very rarely does our planet actually go through it. The animation below shows location of the stream with respect to the Earth (=the line) throughout the years.
The model we used is briefly described here. The location of the trail with respect to the Earth is shown below.
Movie showing the evolution of the 1900 trail in the Solar System (J. Vaubaillon - IMCCE ; Aknowledgements: CINES supercomputer facilities)
View of the stream in the vicinity of the Earth path, on Oct 2011.
Close view of the stream and identification of the trails
As can be seen, the earth will encounter trails ejected during the 19th century, as well as in 1900. As a consequence, two outbursts are expected on October 8, 2011, with maxima respectively at 17:09 UT and 19:57 UT. These timings will allow people from Central Asia as well as Europe to witness the events. Note that the time of first outburst caused by the trails ejected during the 19th century is based on extrapolation of the orbit of that parent comet, since the comet was not yet discovered at that time, making the forecasting uncertain. Interestingly, this first outburst will be the occasion to probe the orbit and study the activity of a comet before it was discovered. The expected level of the shower is around 60 events per hour, but this number is highly uncertain for the above-mentioned reasons.
What is extremely exciting, is the perspective of experiencing and meteor outburst from the trail that we "know", in the sense that the Earth has already encountered it in the past. The level of the shower has been computed with two different methods. The first one is based on our past experience on the photometry of the parent body. However, such information for the time of ejection of the trail is not available, or at least not accurate enough for our investigation. Instead, we have compared the post-predictions of the 1933 and 1946 storms and compared them with the coming 2011 outburst. As already pointed out by Watanabe and Sato (2008), the only way to explain the relative strength of the storms is to invoke a change of activity of the comet. This is the reason why the 1933 storm was mainly used in these predictions. By doing so, we end up with a level of the shower around 600 events per hour. In addition, no other outburst is expected for the coming 40 years! This is an exceptional event that no one should miss!
Everybody is invited and encouraged to enjoy the show, as well as to participate into the scientific efforts, by sending reports to the international meteor organization. This is by far the most useful contribution that amateurs can do. If you need a device to observe the shower, please have a look at the visual meteor observation webpage. Otherwise, you can just enjoy the show with your family! For this, the only thing you need is a clear sky (that is to say, far from any light pollution and no cloud at all). Remember that meteors are visible by naked eye, so you do not need a telescope to observe them. This is why meteors are fun and easy to observe!
If you want to setup a double-station meteor orbit obsevation, feel free to use :
F. Colas (IMCCE) in collaboration with the "Observatoire de Midi Pyrennees" running the "Observatoire du Pic du Midi" is organzing a star party at the Pic du Midi for the event!ALL INFORMATIONS AVAILABLE HERE (French)
As a tool to help organize your observation, J. Anderson (U. Manitoba) was kind to provide us with a weather statistic map, reproduced here with his authorization. The following maps provide you with the cloud cover statistics in early October for a given region in the world. You can see that the Mediterranean area is better than Northern Europe, but the radiant of the Draconids (and hence the number of visible meteors) will be lower. Note also that the Moon will be almost full at the time of the shower.
Weather statistics for Europe
Weather statistics for Central Asia
At IMCCE and in collaboration with researchers from all over the world, we are making all our efforts to organize an airborne-based observation campaign. In the past, many similar campaigns have been organized by Peter Jenniskens (SETI Institute), ensuring the feasibility of such a project. To our knowledge, this is the first time that such a campaign is organized in Europe by Europeans.
Courtesy of SAFIRE - CNRS
IMCCE past experience with airborne observation campaigns include:
Courtesy of SAFIRE - CNRS
The idea is to use research dedicated aircrafts, specifically the French SAFIRE (CNRS) and the German equivalent Falcon 20 (DLR) and have the two aircrafts fly together over Scandinavia (mainly Finland), separated by 100 km (as has already been done during the 2007 Aurigids). We will put as many cameras as possible (and allowed) in each plane and measure the flux of particles, the orbit of the meteoroids (in order to derive their specific origin) and meteor spectra (in order to know their chemical composition). Much is expected from such a unique campaign!
DLR Falcon 20 ; Courtesy of DLR and EUFAR
Flight plan. The first part aims at observing the first peak and will be performed by SAFIRE only. There will be one short hour to refuel at Kiruna between the 2 peaks. Then we will fly to the West along with the DLR Falcon to observe the second peak and triangulate the trajectory of the meteors (to compute orbits and get insight on the origin of the shower).
In late January, INSU via CSA (French research agency) has granted us with the funds necessary to fly the airplane! In early Spetember, P. Koten (Ondrejov observatory) and J. Hatton (ESA) got the confirmation that EUFAR will support the mission!
Below is a drawing showing the location of the cameras in the SAFIRE airplane.
Draft for the configuration of the cameras in the SAFIRE / CNRS aircraft, showing the location of the cameras in the cabin (R. Caillou, SAFIRE/CNRS).
In mid-September, all the cameras will be brought to Toulouse - Francazal for integration into the aircraft. Here is the general schedule:
The mission was a success!!! The aircraft took off and landed without any problem or delay and allowed us to cover the 2 peaks. The flight plan was not ideal for the second peak, but P. Koten (Ondrejov Observatory, the Czech Repulic) computed the best observation configuration within the aircraft. A few cameras did not work as expected but globally the observation was excellent! We learned a lot, but most important, the Draconids showed up right on time! As of Tue. 11th very few data were processed but IMO already confirmed the outburst around 20:00UT.
So apparently the Draconids showed up on time for the second peak, but were much less abundant than predicted. However, as announced in the prediction description article, the level of the shower was estimated from past observations (1933 and 1946). At these times, the observation protocol as defined by Koschak and Rendtel (1990) was of course unknown, so it was hard to evaluate the accuracy of such reports. One of the goal of the campaign was to know what really happened in those years: providing the dynamical model is correct, it seems that the level was a factor of 2 or 3 lower than previously thought. Now is the dynamical model correct? Well, the peak happened around 20:00 UT, that is almost exactly as predicted (19:56 UT), so it shows once more that the prediction of meteor showers/outburst/storms works very well AS LONG AS THE PARENT BODY AND THE YEAR OF EJECTION OF THE TRAIL are known.
What about the first peak? I did not see it, but I was running from one camera to the other (one stopped working at the worse time actually). J. Toth reported 14 meteors from the ground after 17:00 UT. A. Leroy and J. Lecacheux also seem to have witnessed it. Further analysis is needed of course, but if confirmed, this shows that the comet is roughly were we thought it was BEFORE its encounter with Jupiter in 1898. The outburst look to have happened later than predicted, by roughly 20 min, which is small, but might tell us something about the past orbit of comet 21P. Further dynamical analysis are therefore necessary to explain this difference. This also shows that, by looking at the sky for one hour, one is able to know where a comet was more than one hundred years ago!
P. Jenniskens already analysed his data and computed the orbit of a few Draconids. The location of the radiant confirms they come from the 1900 trail.
In the meanwhile, S. Bouley and L. Maquet joined pros and amators in Greece (isle of Rhodes) but the wheather did not allow them to observe the second peak.
For education purpose, J. Mouette (IAP/CNRS) is making a documentary on behalf of CNRS. This documentary will later on be frely available at CNRS-images. Japanese TV NHK is also making a documentary for the public thanks to I. White efforts and a NHK team.
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