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"Aernus", A proposed new planet in the Kuiper Belt
alan
post Jun 20 2008, 09:06 PM
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QUOTE (JRehling @ Jun 20 2008, 01:51 PM) *
Actually, it could be spherically distributed and the searches still be biased if the searchers BELIEVE that it's not. But the fact that more objects are in prograde orbits than retrograde indicates some degree of nonrandomization. However, the fact that some highly inclined orbits have been discovered does NOT mean that searchers are looking outside the ecliptic -- inclined orbits cross the ecliptic.

The larger point is that the orbits definitely deviate from the ecliptic, though not fully randomly. But we can't use the discovered objects to characterize the population because of a bias in the searches. The mean inclination observed so far can't be used as a measure of the actual mean inclination.

Mike Brown's search for large objects extended a significant distance from the ecliptic, Eris and 2005 EL61 were discovered roughly 30 degrees north of the ecliptic.
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Greg Hullender
post Jun 21 2008, 11:31 PM
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QUOTE (JRehling @ Jun 20 2008, 10:51 AM) *
Actually, it could be spherically distributed and the searches still be biased if the searchers BELIEVE that it's not.


Actually, no. If the objects were spherically distributed, then observers looking on the ecliptic would not find more objects than observers looking away from it. That would not be consistent with YOUR claim that looking near the ecliptic "will be the best use of telescope time if your aim is to maximize discoveries."

Or did you mean to include yourself among the biased researchers? :-)

--Greg
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nprev
post Jun 22 2008, 01:14 AM
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I doubt that there actually is a spherical distribution of KBOs, though there certainly have to be a few in radically inclined orbits, perhaps even polar. What I expect is a normal distribution centered on the ecliptic, with a very gentle curve slope on each side...i.e., a really fat torus compared to the Asteroid Belt.


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brellis
post Jun 22 2008, 01:17 AM
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To what extent can detection of as-yet-undiscovered SS objects be automated? Couldn't a 'puter follow the images obtained from a craft surveying the entire celestial sphere, and automatically flag objects that move between images?
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nprev
post Jun 22 2008, 01:22 AM
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Well, at least the NH team will be investigating the region achievable post-Pluto with unprecedented detail.

Kinda like the idea of a dedicated KBO finder mission, but it might have to stare at a given patch of sky for quite some time to pick anything up (esp. very distant objects), and there's a lot of sky to cover.


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JRehling
post Jun 22 2008, 07:49 AM
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QUOTE (Greg Hullender @ Jun 21 2008, 04:31 PM) *
Actually, no. If the objects were spherically distributed, then observers looking on the ecliptic would not find more objects than observers looking away from it.


I never said otherwise.

QUOTE (Greg Hullender @ Jun 21 2008, 04:31 PM) *
That would not be consistent with YOUR claim that looking near the ecliptic "will be the best use of telescope time if your aim is to maximize discoveries."


Again: Researchers will concentrate on the ecliptic if they BELIEVE that that maximizes discoveries, so a concentration of discovered bodies near the ecliptic is not evidence that there is no spherical distribution. It may be true or not true, but the pattern of discovered bodies doesn't prove that.

I do not believe that there is a spherical distribution, so I believe that the researchers are correctly directing their surveys... if their goal is to maximize the number of discovered bodies.

It is not strictly necessary to look anywhere but the ecliptic in order to characterize the obliquity of the population, but it is necessary to publish the details of the survey in order to translate the discoveries into the obliquity of the population. The page I linked to notes that this has not been adequately described by the surveys they cite.
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dvandorn
post Jun 22 2008, 04:08 PM
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Okay -- let's look at this from the back forward, rather than as a snapshot of "right now."

The Solar System accreted from an accretion disk, correct? Every body that accreted from this disk occupies a pertty narrow range of obliquities, within less than 10 degrees of one another. This covers everything from Mercury out to Neptune. It includes all but the smallest of the asteroids, as well.

Then we find a population of bodies that does *not* fall neatly into that ecliptic plane. What is the most natural conclusion to be drawn from that? The conclusion I draw is that the accretion disk had ceased to be a flat disk by the time we got out that far from the sun. Lack of tidal forces and all that.

So, matter that is still gravitationally attached to the Sun but beyond the forces that draw the matter into a disk -- in what way would it form itself? I would think physics would demand that such matter would arrange itself as a sphere around the Sun. Just as the farther-out shell of cometary debris, the Oort cloud, has.

Now, I will admit that I haven't read each survey. But from the results that get talked about (i.e., the discovery of pretty much any body large enough to have been found thus far), not only are we *not* seeing a majority of these objects in the ecliptic, my understanding is that *none* of the more massive objects have been found in anything except inclined orbits.

What does it say about the general distribution of KBO objects when none of the larger members of that population thus far discovered orbit within the ecliptic? How can that be worked back into a population that has its greatest density in the ecliptic with a population that thins out as you move away from the ecliptic (i.e., a torus)?

This is the logic chain that leads me to believe that the KBO population distribution is closer to spherical than to a toroidal "belt."

As with all things, I could, of course, be wrong... rolleyes.gif

-the other Doug


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Del Palmer
post Jun 22 2008, 04:32 PM
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QUOTE (dvandorn @ Jun 22 2008, 05:08 PM) *
Then we find a population of bodies that does *not* fall neatly into that ecliptic plane. What is the most natural conclusion to be drawn from that? The conclusion I draw is that the accretion disk had ceased to be a flat disk by the time we got out that far from the sun. Lack of tidal forces and all that.


Er, not quite. You need a lot of energy to escape the ecliptic plane. Those high-inclination bodies are known as "scattered-disk" objects -- they were most likely formed in the ecliptic plane but were gravitationally tossed into such odd orbits by Neptune.

QUOTE
Just as the farther-out shell of cometary debris, the Oort cloud, has.


Likewise, those objects are believed to have been put there by Jupiter and Saturn...


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dvandorn
post Jun 22 2008, 05:10 PM
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QUOTE (Del Palmer @ Jun 22 2008, 11:32 AM) *
You need a lot of energy to escape the ecliptic plane.

Only if you started out there in the first place.

Also, I have an image of an evolving Solar System that resembles many of the stars-with-disks that Hubble has imaged. Most of these have been in "nursery" nebulae, and the new star is in the process of clearing the smallest gas and dust particles from its vicinity. There is usually a half-spherical "bow shock" effect along the interface between the star's out-pushing solar wind and the dust and gas in the nebula, often defined by the star's trajectory through the nebula.

So -- you have a newly-formed Sol with its accretion disk forming the majority of the Solar System, and a half-sphere shell of bow shock between its solar wind and the gas and dust of the nebula in which it formed. Thus you have accretion going on in two different places, out of two different basic types of materials, one in a tightly planar disk and another along the surface of a spherical area of interaction between the star's violent outgassing and the womb of the nursery that gave it birth.

In such a genesis scenario, I can easily see population of outer system objects being created in spherical shells at various distances from the Sun, remnants of conditions throughout the first few million years after Sol formed.

Again -- I'm not running this through mathematical models. I'm just putting together what I've learned with what I've observed. And while I *do* understand that most current theories still try and keep the genesis of all SS objects as within the accretion disk and discount the possibility of non-planar accretion, I guess I'm saying that my temptation is to describe that thinking as "clinging to" a planar-only genesis concept. I've seen almost nothing in print on the concept of accretion along a bow shock wave in such curcumstances.

In my little gedanken-model, here, I see the current state of the outer System as a depleted version of a young system, which would contain a nice little set of worlds accreted out of a disk and a vast, low-density cloud of "wastage" formed roughly into a sphere around the star. Gravitic resonances from the planar System as well as perturbations by passing stars will have altered it significantly over the life of the System. But my image is still of a roughly spherical shell of only lightly assembled flotsam.

-the other Doug


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Greg Hullender
post Jun 24 2008, 03:32 PM
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Patryck responded to my e-mail:

"Thank you for your email and interest in my research. I believe there was a mistake in the news because I have not written a new paper to the Astrophysical Journal. The results are based on the same paper published in the April issue of the Astronomical Journal."

Oh well. At least we know.

--Greg
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icaru
post Sep 21 2008, 08:09 AM
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Hello everybody!

I'm a student in an engineering school in Paris, France.


I have to find a subject of contreversy ( like "the dangers of cellulars phones ) for a work. In a french review ( Ciel et espace ), I read an article about Aernus and I found more informations on internet through the work of Patryk Lykawka and Tadashi Mukai.
It's very interesting, I find a lot of informations coming from Patryck Lykawka.


My subject mut be a contreversy, so: Do you know the name of scientist, journalists( from serious magazines, not from a people magazine...) or people who don't agree with Patryk Lykawka and don't believe in the existence of a new planet?
If you have websites talking about Aernus(for and against this theory), I would be interested too.
I ask this question because I have the impression that Mr Lylawka is the only scientist interested in this subject. unsure.gif



Thank you for any replies. smile.gif


PS: Sorry for my mistakes !
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Greg Hullender
post Sep 21 2008, 03:12 PM
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Have you looked at issues of Astronomical Journal immediately following the one in which Patryck's article appeared? Find those and carefully look at the letters to the editor. If there is someone with a strong contrary opinion, that person will likely have written a letter within a month or two of Patryck's paper, explaining why he or she doesn't believe it. You could also e-mail Patryck and ask him yourself.

--Greg
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alan
post Sep 21 2008, 03:41 PM
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Patryck Lykawka proposed his planet as an explanation for the dynamical structure of the Kuiper Belt, particularly its cutoff at roughly 48 AU. I've seen Alessandro Morbidelli listed among the authors of a number of papers modeling the primordial origin of this structure, although I don't remember him specifically mentioning Lykawka's explanation. Searching for some of his papers (try here : http://adsabs.harvard.edu/abstract_service.html ) would be a good place to start.
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icaru
post Sep 21 2008, 08:37 PM
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Thank you for your answers!


Greg Hullender, I found the name of scientists who don't agree with Patryk in the answer of Patryk for a journalist french!
Thank you for your help!




In fact I must talk about a controversy tomorrow to my teacher during 5 minutes! If the subject is interesting in relation to the subject of my "colleagues"(the hydrogen for cars and an other : the dangers of antidepressants), we'll continue on Aernus. I'm in a hurry, so I prefer waiting before sending an e-mail to Patryk Lykawka. rolleyes.gif


Bye bye! wink.gif
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