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KIC 8462852[1] (unofficially called WTF) (Read 16593 times)
Bob
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #15 - 10/19/15 at 09:20:00
 
A quick couple of questions, the Hildas, seem to interact with only about a quarter of the Trojans, what happens when one collides with a Trojan? A rare event but not as rare as a comet hitting a Trojan.
 
2: Can a Hilda, object swap with a Trojan?
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #16 - 10/20/15 at 02:47:28
 
It looks like the Hildas can run asymmetrically.  
Try this one  
ln(3.793667894) / ln(2)
So that 1.333333333333 / 0.69314718 = 1.923593388
2^1.923593388
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Bob
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #17 - 10/20/15 at 23:34:13
 
This one from this board looks good. Note that "breathing" effect, I think that is somehow controlled by the Hildas. http://www.orbitsimulator.com/yabbfiles/Attachments/GravSim_JupiterTrojans_1Jup_ Rev.gif
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #18 - 10/21/15 at 12:56:09
 
Quote:
A quick couple of questions, the Hildas, seem to interact with only about a quarter of the Trojans, what happens when one collides with a Trojan? A rare event but not as rare as a comet hitting a Trojan.
2: Can a Hilda, object swap with a Trojan?

In the simulations, they can't interact.  The Hildas and Trojans are massless particles.  In the real solar system they are not massive enough to have appreciable gravity, so they don't interact either.  I doubt they can swap since their semi-major axes are totally different.
 
Quote:
It looks like the Hildas can run asymmetrically.  
Try this one  
ln(3.793667894) / ln(2)
So that 1.333333333333 / 0.69314718 = 1.923593388
2^1.923593388

I'm not quite sure what you're doing here?
 
Quote:
This one from this board looks good. Note that "breathing" effect, I think that is somehow controlled by the Hildas. http://www.orbitsimulator.com/yabbfiles/Attachments/GravSim_JupiterTrojans_1Jup_ Rev.gif

There are no Hildas in the simulation that made this animation.  Even if there were, they would be massless and unable to affect anything.
The "breathing" effect is from Jupiter's eccentricity.
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #19 - 10/27/15 at 03:52:07
 
What I get is that because of orbital velocity changes on one leg of our sixty degree triangle, we get more asteroids at one Trojan point than the other two.That's down to changes in orbital velocity due to Jupiter being at aphelion or perihelion. But that cycles, and at times we can have the leading Trojan point having more or less than the other two. We see an asymmetry of the light dips.
 
  Well, that's all well and good but we have to swap the numbers. There are very few Hildas v Trojans. We have about a million 1km diameter Trojans, and only about 1200 Hildas. A set up with about 75% Hildas is going to be reasonably stable but why do two solar systems arrange asteroids so differently?
 
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #20 - 10/31/15 at 00:31:14
 
One possibility , without having analysed the full paper content ,  if we assume the trojan scenario , is that the first dip at 800 days may be due to giant planet transit . The irregular dips at around 1550 days may be due to a trojan swarm transit either leading or trailing . This means 750 days between the trojans and the giant planet ( 60°) . This means a period for the planet of about 6*750 days = ca. 4500 days .
Assuming the mass of the star having 1.43 solar mass ( wiki ) , we get an SMA for the planet of 6 AU.
Orbital period and SMA are same order as our Jupiter  .  
If the hypothesis is correct the light curve should show dips  around about 50 days ( a few are there)  
Edit the following sentence is incorrect: or at 1550+750=2300 ( no data available ) .  
.  
I don't know if the trojans can have enough mass (or surface) to explain the rather serious dips.  
 
Edit : checking the transit time of the hypothetical planet which would cause the dip in the light curve at ca. 800 days , assuming it being at 6AU gives a transit time of about 1.3 days . This might correspond to the dip in the light curve at ca. 800 days , which seems to be in the order of 1.5-2 days .
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« Last Edit: 11/01/15 at 01:07:11 by frankuitaalst »  
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #21 - 10/31/15 at 23:36:36
 
I commented on this guy's blog, and he seems to think that we would need a lot more Jupiter Trojans than our solar system has. The stuff on KIC is the third blog.
 
http://aleph.se/andart2/
 
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #22 - 11/01/15 at 03:30:34
 
Yes , a lot more trojans than in our solar system , is one possibility .  
Another possibility are coorbitals.
It may be possible that the supposed gas giant has some coorbital planets in the same orbit . Such a system has a lot of dynamical behaviour .
I remember once having simulated our Earth having up to five or six companions in the same orbit .  
AFAIR the system was stable in SMA , but showed a lot of dynamics , meaning planets moving towards each other in their orbit quite close .
Maybe Tony joins in here to express his experience ..
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #23 - 11/01/15 at 08:31:48
 
Yeah, the planet that is supposed to have hit the proto-Earth may have been a co-orbital.  
 
Edited;- But we still have that huge 22% dip. So if we up the percentage of Hildas, then we are going to have low velocity collisions around the Lagrange points. So maybe push the sum mass up to something like the Moon's mass, and have a natural log curve for the collision debris. I think we need to be thinking in terms of surface area, of masses from a km in diameter down to metres in diameter. As they are low velocity collisions, we're not going to get a lot of dust.
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #24 - 11/01/15 at 11:21:23
 
To illustrate the dynamical behaviour of possible coorbitals :  
hereby an animation I created some years ago , of 6 Earth planets originally positioned at 60° in our solar system  
After a while the system gets excited  ie chaotical in Mean Anomaly , but preserving the SMA to the central star .  
Such a system resembles a trojan system , but with the difference  the notion of L4 and L5 points becomes irrelevant , because every coorbital may in fact be found  outside the L4 and L5 points.  
 
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0_60_120_180_240_300_Earths_Anim_5000y_.gif
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #25 - 11/01/15 at 17:42:00
 
Quote:
he seems to think that we would need a lot more Jupiter Trojans than our solar system has

It would have to have more Trojans than Jupiter.  We discovered Jupiter's trojans with telescopes, not by noticing large patches of star fields disappearing from our skies.  Otherwise, the ancient civilizations would have discovered Jupiter's trojans.
 
The problem with trojans is that they should have periodic motion.
 
Also, if there were so many trojans that they could noticeably block light, there would be lots of collisions between them.  They would grind themselves so fine that the stellar wind would blow them away.
 
Quote:
It may be possible that the supposed gas giant has some coorbital planets in the same orbit . Such a system has a lot of dynamical behaviour .

This dynamically behavior is only evident in a rotating frame over long periods of time.  We aren't viewing this star in a rotating frame.
 
I mentioned earlier about a super-Saturn.  I didn't read the paper.  Have they ruled this out based on IR or for other reasons?  To an outside observer, Saturn would cause the greatest light dip on the Sun.  It's also the only thing that would cause a non-symmetric dip, as it is not spherical.
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #26 - 11/02/15 at 02:31:17
 
Won't it work rather like a pair of tinted glasses? I've got a pair of tinted glasses, which are barely tinted, looking out of them there's next to no change in light, but seen from twenty metres away, people see the tint. Here we're talking about a few A.U's but now the people are standing 1400 light years away.  
 
Neptune has ten times as many 1km diameter Trojans as Jupiter, that's the estimate according to Wiki.  Their density suggests that they are basically dirty ice. Their relative velocities are so low that they can just stick together. It might well be that dumbbell comets come from that swarm. But back to Jupiter's Trojans and Hildas, they knock chunks off each other over four billion years but do they grind each other to dust? Mightn't it be the case that very small fragments, from collisions, build up slightly larger fragments over time? So that we have building and demolition going on constantly.
 
We could just wait and see what SETI says; they say a paper will be out in about a month or so, but it would be a laugh to pip them to the post.
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #27 - 11/02/15 at 03:20:33
 
Quote from Bob on 11/02/15 at 02:31:17:
Neptune has ten times as many 1km diameter Trojans as Jupiter, that's the estimate according to Wiki.  Their density suggests that they are basically dirty ice. Their relative velocities are so low that they can just stick together. It might well be that dumbbell comets come from that swarm. But back to Jupiter's Trojans and Hildas, they knock chunks off each other over four billion years but do they grind each other to dust? Mightn't it be the case that very small fragments, from collisions, build up slightly larger fragments over time? So that we have building and demolition going on constantly.
.
I'm not sure either if the trojan population of Jupiter is yet built up into bigger bodies or is grinded up to smaller bodies.
I've no reference I'm aware of . Personnaly I guess both processes are going on , both building and also grinding .  
I can imagine fi. that in case two trojans collide in a frontal collision their mutual velocity is reduced to zero and under good cirumstances the resulting debris stays in the neighbourhood and gradually is reabsorbed by the new trojan , resulting in a trojan having more or less the mass of both parental trojans.  Other scenarios however are also easily to imagine.  
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #28 - 11/02/15 at 23:04:29
 
frankuitaalst, do your co-orbital planets start out as that? We have just a lot of dust which needs to form into a planet. So does it do that, then migrate; with several others into the co-orbital configuration?  
 
I've never been a great fan of the idea of some co-orbital, the size of Mars, forming, then being deflected by Venus and Mercury into hitting a proto-Earth. Too much of a good thing for NASA's graphic designers I fear. I actually prefer Darwin's theory. A proto-Earth, a gas giant the size of Jupiter, throws out Mars as it condenses, and needs to dump angular momentum.
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Re: KIC 8462852[1] (unofficially called WTF)
Reply #29 - 11/02/15 at 23:34:20
 
Quote from Bob on 11/02/15 at 23:04:29:
frankuitaalst, do your co-orbital planets start out as that? We have just a lot of dust which needs to form into a planet. So does it do that, then migrate; with several others into the co-orbital configuration?

I've never been a great fan of the idea of some co-orbital, the size of Mars, forming, then being deflected by Venus and Mercury into hitting a proto-Earth. Too much of a good thing for NASA's graphic designers I fear. I actually prefer Darwin's theory. A proto-Earth, a gas giant the size of Jupiter, throws out Mars as it condenses, and needs to dump angular momentum.

In the simulation above I made I just wanted to examine the stability of coorbitals . They seem to be stable in SMA , ie. once being created they seem to stay where they are . So , yes , I originally put them all at 60° in one orbit and let them evolve over time.  
The sim doesn't take into account in any way accretion of dust or whatever .  
 
I could have done this with 6 Jupiter sized planets also at Jupiters distance to the sun. I guess the result might be the same except for the time scale.  
At Jupiters distance to the sun the coorbitals might evolve slower .  
Edit : IIRC : I somewhere read that there is a maximum of coorbital bodies which holds the system stable . Fi. if the mass concentration gets to high the system experiences the influence of Mutual potential energy which results in instability . The above simulation is well under this limit .
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