[meteorite-list] 2003 EL61, IN PERSON

From: Larry Lebofsky <lebofsky_at_meteoritecentral.com>
Date: Tue Sep 19 23:56:20 2006
Message-ID: <1158724574.4510bbde94d1d_at_hindmost.LPL.Arizona.EDU>

Sterling:

And you wonder why some of us are concerned with the dynamical definitions for
planets. Most of us do not understand the models and even the dynamicists
cannot come to agreement.

Oh, something to remember, when things bump into each other early on, things
stick thanks to there being a lot of stuff in similar orbits. Once that is
gone, impact velocities go up and things break up instead of accreate. If
memory serves me (not very well these days), things should be moving slower
relative to each other so easier to stick. I will have to check on that.

Larry

Quoting "Sterling K. Webb" <sterling_k_webb_at_sbcglobal.net>:

> Hi, E.P., List,
>
>
> > Yes, cometesimals - about 75 meters or so, which
> > themselves can then accrete chaotically over time,
>
> Yes, but nobody thinks cometesimals contain
> enough iron-nickel to form a differentiated body.
> They may, but nobody believes it...
>
> When I expressed a doubt about accreting big
> bodies out in the Kuiper Belt to a professional, he
> said, "What else could it be?" Good question.
>
> > ...over time...
>
> The problem is elbow room and simple geometry.
> How much elbow room do you have? Accretion
> occurs because things bump into each other, because
> the space is crowded, like a NY cocktail party.
>
> Clearly, the Earth accreted. If it sucked up every
> rock from 0.80 AU out to 1.30 AU, it was drawing
> on a "zone" with an area of about 0.80 "square AU's."
> (The area of a circle 1.3 AU in diameter minus the
> area of a circle 0.8 AU in diameter = "the Accretion
> Zone.") Yes, it was a volume, because it had thickness,
> but it was a flat disc.
>
> It was crowded. Rocks kept meeting rocks. It
> happened in a hurry -- blam, Blam, BLAM, all done.
> 10 million years? 30? 50? Opinions vary, but quick,
> all agree.
>
> Out in the Kuiper Belt, very narrowly defined as
> from 38 AU out to 48 AU, there's 1583 "square AU's"!
> That's almost 2000 times more room! Your odds of
> bumping into something are 2000 times smaller.
>
> Imagine you're in a ballroom with 3999 other
> people, all 4000 of you milling around in constant
> motion and blindfolded so you can't look where
> you're going: bump, Bump, BUMP.
>
> Now, imagine that you're in the SAME ballroom
> with one other person (just the two of you). What
> are the chances of you two (blindfolded and with
> ear plugs) colliding?
>
> Well, since your odds of meeting up are 2000
> times smaller, it's going to take 2000 times as long
> for it to happen. Hey, no problemo! If the Earth
> accretes in a snappy 10 million years, then objects
> in the Kuiper Belt will accrete in only... scribble,
> scribble... 20 Billion Years!
>
> No, wait! Does that sound wrong to you?
> You see the problem...
>
> Well, the theoretical dynamicists must have
> an answer, something we haven't thought of,
> right? They do indeed have solutions. What
> are they?
>
> Simple, just put 100 times more mass in the
> Kuiper Belt (or 200 times more or 500 times more)
> and it speeds things up to where bodies can accrete
> there in ONLY a billion years or less! Or more...
>
> Wow, the Kuiper Belt must be MASSIVE!
> Oh, no, they reply, the whole thing has less than
> 0.10 Earth masses for all objects big and small.
> All that mass is gone...
>
> I smell a problem. It took the inner solar system,
> where things accrete in a flash, 600 million years to
> clean up the leftovers (the Late Bombardment, you
> remember; it was a big hit). The same process in the
> Kuiper Belt? With 100 times the mass, it will take
> 20 times as long (6 billion years). The leftovers
> should still be there. If not, where'd the mass go?
>
> There are lots of "mass-wasting" theories. I didn't
> invent that silly term; that's what they're called.
>
> Not to go on too long, the answer is: it got swept
> under the rug. There are numerous complicated and
> unlikely scenarios. Julio Fernandez and school push
> a theory in which Neptune, pumped up by a resonance
> with Saturn, spirals outward (while the other giants
> spiral inward), with Neptune pushing the KB in front
> of it, compressing it and making fast accretion happen,
> until Neptune finally stops with the KB on its doorstep,
> where Neptune can then spend billions of years
> perturbing the rest of the mass away, and leaving
> little total mass for the Kuiper Belt.
>
> Of course, they could just be WRONG about the
> mass-poor Kuiper Belt. Look a sharp, economical test
> of Kuiper Belt theory described in:
> http://www.nature.com/nature/journal/v442/n7103/full/442640a.html
> The data had already been collected by NASA.
> (The full article is at:
> http://www.nature.com/nature/journal/v442/n7103/full/nature04941.html)
> They found perhaps 1000 times more mass than
> theory allows. So maybe the mass is still there?
>
> One prediction of theory is that the Kuiper Belt has
> a sharply cut-off outer edge, and that past that edge,
> there are no more TNO's all the way out to the Oort
> Cloud, a great deserted and empty zone, with a sign
> at 42 AU or 48 AU that says: "Now leaving the Solar
> System. No Gas Stations for 20,000 AU." In other
> words, there's nothing out there TO find.
>
> This, of course, is where all the bolts come loose
> and the wheels fall off! This is exactly where we are
> finding things. First called the "Scattered Disc" (on
> the assumption that Neptune tossed'em out there) and
> then the "Extended Scattered Disk," or the "Distant
> Detached Disc," we now have a slew of large interesting
> objects that Neptune could never have had anything to
> do with.
>
> Finding Sedna was kind of a last straw. Brown, who
> discovered it says, "Sedna shouldn't be there. There's
> no way to put Sedna where it is. It never comes close
> enough to be affected by the sun, but it never goes far
> enough away from the sun to be affected by other stars...
> Sedna is stuck, frozen in place; there's no way to move it,
> basically there's no way to put it there - unless it formed
> there. But it's in a very elliptical orbit like that. It simply
> can't be there. There's no possible way - except it is.
> So how, then?"
>
> Sedna has been "explained" as an Oort Cloud object,
> which tacitly moves the inner Oort Cloud boundary in
> from 20,000 AU to under 1000 AU and creates an "Oort
> Disc" in the bargain! Those Oortians are sneaky... They
> creep right up on you.
>
> Then some theoreticians have claimed that Sedna
> is the captured planet of another star. Kenyon at Harvard
> CfA: "If we find planets with orbital inclinations of more
> than 40?, it is almost certain that these are extrasolar
> planets formed in another solar system." Then, along
> comes ERIS, the former 2003 UB313, which meets that
> qualification. Extra-solar planet?
>
> > ...it would be real nice to get some
> > good spectra of 2003 EL61 right now...
>
> Oh, for one lousy gritty gram of sample return, as
> there are only about 80 isotope assays any one of which
> could decide between material formed with Our Star or
> formed with Some Other Star!
>
> All these high inclination objects have also provided
> a big boost to the "Sun's Companion Star" theories
> we all remember so well, like Nemesis. It still has its
> backers, and they're all elated. Of course, what they
> don't tell you is that you don't need a brown dwarf
> star to perturb disc objects in inclination; all you
> need is an Earth mass object at 1200 AU. The Outer
> Outer System is waiting to be discovered... I think.
>
> Then, there's 2005 XR190, code name "Buffy." If
> Sedna is impossible, then "Buffy" is impossibility cubed!
> The size of Ceres, it's in a nice normal almost CIRCULAR
> orbit inclined at 45 degrees to the solar system at 52 to
> 62 AU's out, dynamically independent of any influence
> from ANY solar system objects and is equally impossible
> as a star capture. "Buffy" is "The Theory Slayer"! Poof!
> Your life's work is dust...
>
> That we are finding ANY high-inclination objects is
> a miracle. Astronomers are STILL just looking at the
> Ecliptic and nowhere else. A high-inclination object is
> near or in the Ecliptic plane for just 2% of its orbital
> travel, so for every one you find there, there are 49
> others you're MISSING, by not looking where they
> are!
>
> Duh!
>
> One of the best times ever is when Reality just flat
> outruns Theory and leaves it panting in the dust, don't
> you think? I certainly do.
>
> Of course, another effect of this situation is that
> the Theory Machines all get their throttles cranked up
> to "Hyper Overdrive" and a lot of Theory Juice gets
> splattered all over the place. What we actually need
> is to let the Theory Machines cool down and collect
> more Reality
>
>
> Sterling K. Webb
> ----------------------------------------------------------
> ----- Original Message -----
> From: "E.P. Grondine" <epgrondine_at_yahoo.com>
> To: <meteorite-list_at_meteoritecentral.com>
> Sent: Tuesday, September 19, 2006 9:23 AM
> Subject: Re: [meteorite-list] 2003 EL61, IN PERSON
>
>
> > Hi Sterling, list -
> >
> > "but core-forming planetesimals all the way out in
> > Kuiper Belt?!"
> >
> > Yes, cometissimals - about 75 meters or so, which
> > themselves can then accrete chaotically over time,
> > with the heavy elements always gravitationally
> > precipitating towards the center - the lighter
> > volatiles always on the outside - and you have
> > delivery to the surfaces of larger bodies -
> >
> > Given the problems this presents us for dealing with
> > cometary impactors, it would be real nice to get some
> > good spectra of 2003 EL61 right now, but as always,
> > this kind of study recieves a low priority from the
> > failed nuclear physicists who control the telescopes
> > and observing budgets -
> >
> > by the way, the 64 fragments of SW3 should be in the
> > Earth's vicinity in 2022, though I don't have any dead
> > on forecasts yet - as a matter of fact, I wonder where
> > they are, and how this is being handled, so if anyone
> > hears anything, please pass it on -
> >
> > good hunting,
> > Ed
> >
> >
> >
>
>

-- 
Dr. Larry A. Lebofsky
Senior Research Scientist
Co-editor, Meteorite                      "If you give a man a fish,   
Lunar and Planetary Laboratory               you feed him for a day.
1541 East University                       If you teach a man to fish,
University of Arizona                        you feed him for a lifetime."
Tucson, AZ 85721-0063                                     ~Chinese Proverb
Phone:  520-621-6947
FAX:    520-621-8364
e-mail: lebofsky_at_lpl.arizona.edu

Received on Tue 19 Sep 2006 11:56:14 PM PDT