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Ceres and Gefion (Read 8643 times)
ScottM
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Ceres and Gefion
05/03/14 at 21:09:55
 
Just for the fun of it (and because I'm an astronomy nerd), I've been studying Ceres a bit as of late. In the course of my research, I found references to Ceres have quasi satellites, and about its interesting orbital relationship with the asteroid Gefion. Ceres was once thought be a member of the asteroid family that is now named after Gefion, and so, I decided to plug the ephemeris data from Horizons into the simulator and observe the relationship myself. Personally, I found the results to be very interesting.
 
I centered the simulation around Ceres and started it. In the beginning, Gefion was in a quasi-orbit around Ceres which had a very large radius. However, as time progressed, the quasi orbit spiraled in closer and closer to Ceres, until Gefion ceased to be a quasi-satellite. Finally, the orbit began to sprial out again, and the quasi-orbit around Ceres resumed.
 
I thought it was pretty interesting how the simulator demonstrated Gefion's moving in and out of the quasi-satellite with Ceres every few years.
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frankuitaalst
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Re: Ceres and Gefion
Reply #1 - 05/04/14 at 09:44:38
 
Hello Scott ,  
 
I just started a sim of Ceres-  Gefion , in rotating frame with Ceres centered .  
As I see both are "coorbitals " .  
At present Gefion approaches Ceres and will overtake it in ca. 70 years from now .  
They  wil seem to be in orbit for a while , but Gefion will continue its orbital .  
The will come close every 350 -400 years about .  
I wonder if you have the same result ?  
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frankuitaalst
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Re: Ceres and Gefion
Reply #2 - 05/04/14 at 10:12:08
 
Here's a screenshot of my simulation , after ca. 100 years from now .  
Gefion's orbit is shown as seen from an observer on the "sun" with Ceres centered in the middle .  
The angle of view is 60.  
Gefion will seem to be in a large orbit around Ceres but will leave its host ....
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PicN65_KM_Grefion__01012009_dat_1013.jpg
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ScottM
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Re: Ceres and Gefion
Reply #3 - 05/04/14 at 11:07:53
 
Ceres was once thought to be a part of the asteroid family now named after Gefion, and there are quite a few asteroids that are co-orbital, both members of the family, like Gefion, and interlopers, like Ceres and Minerva.
 
I didn't run the simulation for long enough last night to make the observations that you did, but when I have more time to do it (maybe tonight), I'll see what I come up with. I want to expand my simulation to include others of the group of co-orbital asteroids and see what else I find. I'm really glad I stumbled across that reference to the orbital relationship. I think this is going to be fun!
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frankuitaalst
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Re: Ceres and Gefion
Reply #4 - 05/04/14 at 11:14:11
 
yes , I see what you mean . Perhaps some members of the family will show up as beeing in some resonance to each other , this is a possibility .  
This means horseshoe type orbits for instance .... Maybe  
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ScottM
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Re: Ceres and Gefion
Reply #5 - 05/04/14 at 11:48:54
 
I'm not sure which asteroids they are, but from some of what I've read, both Ceres and Vesta currently have quasi-satellites. I'm hoping if I add more of the Gefion family or its interlopers to the simulation I can learn more about it. I'll be sure to share anything I find.
 
When I'm through with my research on Ceres, I plan to do Vesta next, so I'll eventually do a simulation for that, too.
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frankuitaalst
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Re: Ceres and Gefion
Reply #6 - 05/04/14 at 12:11:31
 
For your infomation Scott : I'm running a short simulation with some of the members of the Gefion family : Minerva , Oppavia , Burgundia .  
All of them are "coorbitals " to Ceres , but none of them seem to come in an orbit or horse-shoe orbit . Maybe some smaller members will .
If you have some idea's please post ....
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frankuitaalst
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Re: Ceres and Gefion
Reply #7 - 05/04/14 at 12:30:35
 
Aah : in  a paper P. Wiegert seems to have found some librating asteroids around Ceres and also Vesta :  
http://arxiv.org/abs/1110.4810
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ScottM
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Re: Ceres and Gefion
Reply #8 - 05/04/14 at 12:33:48
 
That's the paper I stumbled upon. I was looking for papers on arxiv dealing with Ceres, and I came across that one. I'm glad you found it. I couldn't remember exactly where I had come across it.
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Re: Ceres and 1372 Haremari and 8877 Rentaro
Reply #9 - 05/04/14 at 12:55:20
 
In the paper above two asteroids are mentionned to be in relation with Ceres :  
1372 Haremari and 8877 Rentaro,
A quick sim in rotating frame to Ceres gives a rather unexepected behaviour of both :  
both seem to be quite stable at around 180 from where Ceres resides in rotating frame.  
If correct ( to be confirmed by others ) , as far as I remember I have never seen this before .
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frankuitaalst
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Re: Ceres and Gefion
Reply #10 - 05/04/14 at 13:04:43
 
Here's a picture in rotating frame of both mentionned asteroids .  
Both seem to reside quite stable in their location relative to Ceres for the next couple of hundred years , only showing some small libration aroud their depicted orbit .  
As I said , never have seen this .  
 
I'm curious to see how other candidates behave . As far as I read the paper only these two were mentionned . The other identified members can be retrieved on demand from the authors ....
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PicN65_KM_Gefion__01012009_dat_1002.jpg
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ScottM
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Re: Ceres and Gefion
Reply #11 - 05/04/14 at 13:24:49
 
I only had time to skim the paper after I found it yesterday. Now that you've reminded me where I found it, I'll read it more carefully when I get a chance. I did see the part about the full list being available on request. I think I'd rather play around with it myself, though, than make the request. I have a feeling that playing around with other Gefion family members could lead to some interesting discoveries.
 
Btw, Wikipedia has a list of quite a few members of the family, if you want to check that out.
 
http://en.wikipedia.org/wiki/Gefion_family
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Re: Ceres and Gefion
Reply #12 - 05/05/14 at 08:59:18
 
In the paper above some asteroids are mentionned , which are worth  some simulation:  
138245  
 
166529
 
71210
 
81522
 
65313 and 129109 persist as L5 Trojans of Ceres,
 
76146 is a Quasi-Satellite of Ceres until .....yr.
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Re: Ceres and Gefion
Reply #13 - 05/05/14 at 12:54:30
 
I'm running a sim with the following asteroids mentionned in the paper above  
 
"138245","yellow",
"166529","red"
"71210","white"
"81522 ","green"
"Haremari","red"
"Rentaro","green"
"65313","white"
" 129109 ","green"
" 76146 ","yellow"
 
Here's a screenshot of the sim , in rotating frame to Ceres ( the red line at ca. 10 'o clock) , in about hundred years from now.  
It seems Ceres has 3 quasi -moons at this time , one red and two yellow .  
If I've some time later this week a probably can make an animation out of these ....
 
Correction : in another view the lower yellow asteroid seems not to circle "around" Ceres but is in a tadpole orbit . It actually seems to be "under " Ceres , therfor not circuling "around" .
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PicN65_KM_Ceres_Coorb_01012009_dat_1020.jpg
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ScottM
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Re: Ceres and Gefion
Reply #14 - 05/05/14 at 17:29:13
 
I'm getting ready to try to play around with this more, but I apparently have a lot to learn about how to use the program.
 
How do I set one object at the center and the rotating frame to another object?
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