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Message started by frankuitaalst on 02/01/09 at 07:02:04

Title: Neptunian Trojans
Post by frankuitaalst on 02/01/09 at 07:02:04

A while ago (2006) Tony made this simulation of the 4 known Neptunian Trojans .
http://orbitsimulator.com/gravity/simulations/NeptuneTrojans.gsim

Beeing occupied for a while by the Neptunian resonances I discovered in the Wiki Pages the number of known Trojans has grown to six nowadays .
All of them are correlated with the L4 point , but each of them has its particular orbit .
The animation herunder shows the path of the 6 Trojans in rotating frame to Neptune .
Each frame covers 164.8 years . Simulation was run for 14500 year from now.  
Initial conditions : courtesy of JPL minor body center .

Title: Re: Neptunian Trojans
Post by NeutronStar on 02/01/09 at 07:24:08

that is awesome! so all are in a 1:1 right?

Title: Re: Neptunian Trojans
Post by frankuitaalst on 02/01/09 at 07:55:17


NeutronStar wrote:
that is awesome! so all are in a 1:1 right?

Yes , right . To be more precise : they all librate around the 1:1 resonance , i.e . they tend to be stable at the L4 point , but "overshoot" and then "decelerate" again .

Title: Re: Neptunian Trojans
Post by Mal on 02/01/09 at 09:28:17

What exactly is Uranus' orbit doing? Is that "flexing" a resonance?

Title: Re: Neptunian Trojans
Post by frankuitaalst on 02/01/09 at 10:13:14


Mal wrote:
What exactly is Uranus' orbit doing? Is that "flexing" a resonance?

Uranus has P 84 y , Neptune has P 164.8 years . So they are almost at 1:2 resonance . If they had been at 1:2 resonance Uranus orbit would appear elliptical and stable . As this isn't the case the orbit seems to precess ...
I don't think Uranus will ever come in resonance with Neptune  

Title: Re: Neptunian Trojans
Post by kheider on 02/01/09 at 10:20:34


Mal wrote:
What exactly is Uranus' orbit doing? Is that "flexing" a resonance?



Uranus is near (coincidental) the 2:1 resonance with Neptune, but it does not librate, thus we get more of a constant 360 degree wobble.  See 2 Pallas on wikipedia for a good example of a non-librating near resonance.
http://en.wikipedia.org/wiki/2_Pallas#Characteristics

Frank;
Which trojan is producing the central poorboy valentine day heart? :-)

Might be nice to have have a simple animation with just him given that valentine's day is coming.
-- Kevin

Title: Re: Neptunian Trojans
Post by frankuitaalst on 02/01/09 at 10:36:53

Nice find ! Don't know .  I'll isolate it !

Title: Re: Neptunian Trojans
Post by Tony on 02/01/09 at 11:16:40

btw... the heart shape, and all the other strange shapes are artifacts of the viewing angle.  If viewed top-down on the orbital plane of the asteroid, it would be a simple oval.

Title: Re: Neptunian Trojans
Post by NeutronStar on 02/01/09 at 13:17:26


Tony wrote:
btw... the heart shape, and all the other strange shapes are artifacts of the viewing angle.  If viewed top-down on the orbital plane of the asteroid, it would be a simple oval.
Take inclination into account too! Izdubar (a co-orbital with earth) make a shape wiht a loop, somwhat like a heart, from top-down.

Title: Re: Neptunian Trojans
Post by NeutronStar on 02/01/09 at 13:19:10


frankuitaalst wrote:
[quote author=Mal link=1233500541/0#3 date=1233509297]What exactly is Uranus' orbit doing? Is that "flexing" a resonance?

Uranus has P 84 y , Neptune has P 164.8 years . So they are almost at 1:2 resonance . If they had been at 1:2 resonance Uranus orbit would appear elliptical and stable . As this isn't the case the orbit seems to precess ...
I don't think Uranus will ever come in resonance with Neptune  
[/quote]
So, that's what they went looking for Neptune for... When they saw that Uranus was not where it was supposed to be they proposed Neptune. And found it!

Title: Re: Neptunian Trojans
Post by kheider on 02/01/09 at 21:23:53


frankuitaalst wrote:
I discovered in the Wiki Pages the number of known Trojans has grown to six nowadays.


I have added your animation to the Neptune Trojan article at:
http://en.wikipedia.org/wiki/Neptune_trojan

(You can click on the image to bring up the full size one and to get more details about the image.)
-- Kevin

Title: Jupiter Trojan
Post by kheider on 02/01/09 at 21:43:02

Currently at Wikipedia, Jupiter Trojans is undergoing a wikipedia peer review for improvement.  They have a generic animation of the orbit of 624 Hektor compared to Jupiter, but I am sure GravSim can do better.  I recommend 624 Hektor because it has the best developed Jupiter trojan wiki article. :-)
http://en.wikipedia.org/wiki/Jupiter_Trojan

-- Kevin

Title: Re: Neptunian Trojans
Post by frankuitaalst on 02/02/09 at 09:46:06


kheider wrote:
[quote author=frankuitaalst link=1233500541/0#0 date=1233500524]I discovered in the Wiki Pages the number of known Trojans has grown to six nowadays.


I have added your animation to the Neptune Trojan article at:
http://en.wikipedia.org/wiki/Neptune_trojan

(You can click on the image to bring up the full size one and to get more details about the image.)
-- Kevin[/quote]
I saw the picture looks a little bit "spicky" due to the downsizing of the original .
I ran the simulation again in a smaller screen for 9000 years .
This animation should be better looking ...



Title: Re: Neptunian Trojans - side view
Post by frankuitaalst on 02/07/09 at 05:20:57

The picture above shows the 6 known Neptunian Trojans on a normal rotating frame to Neptune .
In order to represent somehow the strong inclination of some of these trojans I created the same simulation , but this time viewed from aside ( to be more precise : Y,Z representation) . You can interprete the animation hereunder as if you were looking at the animation above from the right side .
Simulation runs for ca. 9400 years , corresponding with the libration period .
Jupiter and Saturn aren't represented .
An interesting by-product is the strange flexing orbit of Uranus in this view which I don't fully understand .

Title: Neptunian Trojans
Post by frankuitaalst on 02/14/09 at 07:39:56

As a present for Valentines day : here's the orbit of 2005TN53, a trojan of Neptune .  :)
Simulation was run for ca. 10.000 y .

Title: New  Neptunian Trojan discovered
Post by frankuitaalst on 08/13/10 at 11:12:08

Mal made us aware a new Trojan has been discovered in the L5 point .
Hereunder is an animation of the known Neptunian trojans so far .
The new trojan is animated in green .
The others at the L4 point are in red .
So the newly discovered one is the first at the L5 "point".
The animation covers 330 years , about 2 Neptunian years from now.
The viewpoint is a fictional point at the opposite side of Neptune .
So we look at Neptune in the center . The orbit of Earth is represented as a reference in blue .

Title: Re: Neptunian Trojans
Post by Mal on 08/13/10 at 13:23:41

I thought I recalled seeing a thread about this on here before :)

Title: Re: Neptunian Trojans
Post by frankuitaalst on 08/15/10 at 04:06:42

A simulation on a longer time-scale of 100 Neptunian years ( ie 16490 Earth years ) gives the following picture .
The viewpoint once again is the "anti" neptune ( lets say more or less the L3 point ).
Also Jupiters orbit is shown , as a reference . Neptune stays centered as a white dot .
The trojans seem to act as a bee-swarm around the L4 point , the lonely green bee at the right is the newly discovered trojan .
This animation shows clearly that in order to find new trojans it isn't sufficient to look at a specific point n the sky ( the L4 or L5) .
Numerous bodies far away from the  L4,L5 point can be candidates for nomination as a trojan once ther orbit has been integrated .  

Title: Re: Neptunian Trojans
Post by frankuitaalst on 08/17/10 at 12:49:47

Additionally I've made the folloswing animation of the motion of the trojans over a timespan of about 9700 years .
This timeperiod seems to cover 1 full libration period .
9700 years is very long compared to the period of jovian trojans which is about 150 years .
I guess the reason for this longer period is the longer orbital period of Neptune and the lower mass of Neptune .
Haven't checked it (if it's checkable in literature ... ) but the relation might be something as : P Trojan = P primary * MassSun / MassPlanet

Title: Re: Neptunian Trojans
Post by Tony on 08/19/10 at 11:06:51

I really like the side view animation.  Have you tried this in 3d with the glasses?

Title: Re: Neptunian Trojans
Post by frankuitaalst on 08/19/10 at 13:50:29

Here's the 3D glasses version .
The anim starts with 100 frames over 1 Neptunian year and then continues for the next 9700 years which corresponds with 1 libration period.
The central point is the sun . Viewpoint is once again the anti Neptune ( ~L3 point )

Title: Re: Neptunian Trojans
Post by Mal on 08/19/10 at 21:39:07

OK, general question - where does one get red/blue glasses from?! I keep seeing 3D images on the net that requires them, but of course modern 3d movies don't use that technology any more! So do you have any suggestions as to where I could find them?

Title: Re: Neptunian Trojans
Post by Tony on 08/19/10 at 22:00:13

Sometimes they're given away in magazines such as Astronomy or Sky & Telescope.  Typing "red blue 3d glasses" into Google will give you a bunch of places to mail order them from.

Title: Re: Neptunian Trojans
Post by frankuitaalst on 08/20/10 at 07:00:24

Mal , if you send me your adres I can send you one I have as spare. Distance Belgium-GB should be doable  :)

Title: Neptunian Trojans update 2014
Post by frankuitaalst on 05/10/14 at 02:09:47

As to date the number of detected Neptunian Trajans has  increased ( Source Wikipedia) .
Here's an update of the system, now having 6 members in L4 and 3 members in L5.
The system looks nicely balanced ; it wouldn't surprise me if in the future the number of Trojans detected increases significantly .
The sim herunder covers 16 k years from now .

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