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Fraser
2004-Nov-12, 05:44 PM
SUMMARY: In June, researchers from the University of Rochester discovered a planet around a star so young that it shouldn't exist according to existing theories of planetary formation. Further observations have backed up the discovery; there's definitely a planet there which is only 100,000 to 500,000 years old. This is much too young for either of the established theories of planetary formation. In the "core accretion" model, larger and larger chunks of rock smash together for 10 million years until a large planet is formed. In the "gravitational instability" model, a cloud of material pulls together into a planet by its own gravity; this is faster, but still not fast enough to explain how the planet got there.

What do you think about this story? Post your comments below.

antoniseb
2004-Nov-12, 05:58 PM
Another theory is that some larger planets begin forming at the same time as the star. When the star reaches a certain point in its development, it starves these proto-planets of new ISM material to accrete. They will then being absorbing material from the accretion disk. This process will bring the planet's orbit into the plane of the disk and circularize it. That may be what we are seeing here.

Duane
2004-Nov-12, 06:32 PM
Or perhaps we are seeing a that it is not one process, but a mixing of several. Back to the models boys and girls! :)

lswinford
2004-Nov-12, 08:19 PM
I think that the planets begin to form first. The larger accretion of material, that center of gravity for the disk, builds up bigger and bigger in the meanwhile, and then later flames into a star, takes the real time.

StarLab
2004-Nov-12, 09:04 PM
Actually, while I never thought about it that way before, Ford's idea makes sense. Hmm.. :blink:

galaxygirl
2004-Nov-13, 12:49 AM
Is it possible that the planet was a rogue planet which was pulled into an orbit of that star?

Duane
2004-Nov-13, 12:51 AM
I don't think so GG, because there is a pretty extensive disc around the star, except for the area where this planet has cleaned it out.

PK
2004-Nov-13, 12:54 AM
yes that's it I recall it explained some time back, but it wasn't this planet it was the possiblity of another. It got blasted out from one sol system due to a supernova and then it became a lost rogue planet, then as suns move through space it became captured by another Star and thus existed around a very young star

om@umr.edu
2004-Nov-13, 01:55 PM
This is an interesting story.

It illustrates a common problem in science.

It is probably correct to assume that rocky planets like Earth, Mars, Venus and Mercury formed by accreting together meteorite-like chunks of material.

That is why the upper mantle is extensively reworked but the lower mantle is relatively primitive.

Radioactive parent/daughter measurements show that planet Earth formed quickly and degassed its upper mantle to produce its crust, atmosphere, and oceans. The gaseous decay products of extinct I-129 and Pu-244 accumulated in the upper mantle, together with those of longer lived K-40, U-235 and U-238.

However, giant gaseous planets like Neptune, Uranus, Saturn and Jupiter cannot form that way. There are no meteorites made of the highly volatile material in those planets.

They probably formed by gravitational collection of highly volatile elements and compounds like H, He, N and methane. This process may, or may not, have required solids to form first and then accrete together.

Many volatile compounds freeze at the low temperatures in the outer solar system today, but the early solar system was hot - continually heated from short-lived radioactive elements made in the supernova that gave birth to the solar system.

Finally, it is noteworthy that the Rochester team are only "backing up the original conclusions, saying they've confirmed that the hole formed in the star's dusty disk could very well have been formed by a new planet."

With kind regards,

Oliver
http://www.umr.edu/~om

Ola D.
2004-Nov-13, 02:30 PM
Here's a brief article that is somehow related to the story discussed here..

Astronomers Discover Planet Building is Big Mess (http://www.nasa.gov/vision/universe/starsgalaxies/spitzer-101804.html)

-- Ola

STELLY
2004-Nov-13, 03:31 PM
It makes perfect sense to me that planets and stars start forming at the same time, which would make Jupiter a Failed Brown Dwarf that was robbed of its chance to get bigger by the ignition of our sun. I totally agree with a combination of the core accretion model and the combination of the same time model. It has really never made sense to me that only stars would start forming and planets would not in the early solar systems and nebulas. Gravity would "clump" together all ranges of sizes of for lack of a better word "clumps" witch would then Interact with the bigger "clumps" and start spiraling in material into "Super clumps" witch would then someday turn into a Star and Protoplanetary Disc with some protoplanets or “clumps” already set in motion by gravity from day one with others on the way with the current core accretion model of planetary formation

antoniseb
2004-Nov-13, 04:38 PM
Originally posted by om@umr.edu@Nov 13 2004, 01:55 PM
Many volatile compounds freeze at the low temperatures in the outer solar system today, but the early solar system was hot - continually heated from short-lived radioactive elements made in the supernova that gave birth to the solar system.
Thanks for a nice outline of planet formation.

I have a few minor quibbles with what you've written. One is the paragraph above. It is safe to say that THE PLANETS in the early solar system were hot, both from impacts and from radioactive decay, but most of the particles in the disk that eventually accreted in to larger object cooled very rapidly. They had a lot of surface area for the given mass, and could radiate heat in minutes, not millions of years. When we make infrared images of the dusty disks around new stars, this model is confirmed. Except very near the star, these disks are cold enough to freeze methane.

My other quibble is in the statement as though it were fact that the lower mantle is primative. We have no samples from the lower mantle. We can't know the isotope ratios, or chemical mixing that has gone on there. Seismic data doesn't tell us it hasn't been reworked.

Duane
2004-Nov-13, 05:15 PM
Seismic data doesn't tell us it hasn't been reworked.

In fact, seismic studies of s and p-wave propagation through the mantle and core has revealed areas of upwelling called "superplumes" that come from the base of the lower mantle at the core and rise all the way up to the lithosphere (see here for example (http://www.seismo.berkeley.edu/~gung/_Qplume/,press/,tampabay/MGAE2PE870D.html)). The process also inolves the sinking of cooled magma in other spots back to the base--in other words the mantle recycles.

I have posted sites to this in the past, which Dr Manuel again ignores.

For more information, check out Prof Barbara Romanowcz's studies at U of C Berkley, or by Jeroen Ritsema and Hendrik van Heijst of the California Institute of Technology, or by Jerry X. Mitrovica of the University of Toronto, or by Cynthia Ebinger of the University of London, or Royal Holloway, in Egham or Stanford University's Norman Sleep, or a host of others.

Get it straight people--the mantle is not only melted throughout, it recycles. Furthermore, the lower mantle is not primitive--it can't be, because it recycles! Dr Manuel can wish it to be different all he wants, the observations prove it to be true.

damienpaul
2004-Nov-13, 05:28 PM
and more, and i mean a tremendous amount more about mantle plumes can be found here (http://www.mantleplumes.org/)

om@umr.edu
2004-Nov-13, 06:04 PM
Sorry folks, but there is overwhelming evidence the lower mantle is primitive.

It has even retained primordial (not radiogenic) He-3.

That primordial He-3 is still leaking out today, through the depleted upper mantle, and appearing at the Earth's surface in Mid-Ocean Ridge Basalts (MORB).

This old ball of dirt we call Earth accreted in layers, beginning with the formation of its iron core by accreting material like that in iron meteorites.

That doesn't fit textbook stories, but that's the way it happened.

You can see the experimental data and find references for the measurements in: "The Noble Gas Record of the Terrestrial Planets"

http://web.umr.edu/~om/archive/NobleGas.pdf

With kind regards,

Oliver
http://www.umr.edu/~om

damienpaul
2004-Nov-13, 06:09 PM
so that website and my many years of geological study (yes i am a geologist by profession as well as a teacher) incorrect...(btw, we never used textbooks, mongrel things to carry into the field)

I had to do a lot of geophysical and seismological work and what duane says has come up again and again in our experiments and observations...certainly a fascinating field though.

I remember when we landed by helicopteron White Island volcano in NZ, for a side trip - AWESOME

I am still involved in seismology but at a less significant way and have not been to white island for a long time

damienpaul
2004-Nov-13, 06:19 PM
Hey wait a sec, how do you know that there is He-3 in the bottom of the mantle????? I mean know for certain????? Then again, I have seismological data that we collected, no chemical data... although if we did - it'd have to come out of a volcano, cause i aint digging no stinkin' hole to the bottom of the stinkin' mantle!!!!

om@umr.edu
2004-Nov-13, 06:23 PM
Originally posted by STELLY@Nov 13 2004, 03:31 PM
It makes perfect sense to me that planets and stars start forming at the same time.
I agree, Stelly.

And welcome to UT!

Many scientists do not want to consider that the Sun, like the planets, formed over a period of time by accretion.

If that happened, heavier elements would sink and accumulate in the interior of the Sun.

The standard solar model wants the inside composition of the Sun to be the same as its surface.

The standard solar model thus assumes that the Sun formed without accretion of material.

See the ApJ paper by Dar and Shaviv, reference #33 in this paper:
http://web.umr.edu/~om/abstracts/ACM-2002.pdf

With kind regards,

Oliver
http://www.umr.edu/~om

(Q)
2004-Nov-13, 06:29 PM
If that happened, heavier elements would sink and accumulate in the interior of the Sun.

What process or mechanism makes the elements "sink" to the interior?

damienpaul
2004-Nov-13, 06:42 PM
Dr. M. can you please explain to me about the He-3 in the mantle, i am very curious - is it from volcanological data? (I did read your article, I have trouble reading, on screen responses seem to work best for me )

om@umr.edu
2004-Nov-13, 06:46 PM
Originally posted by antoniseb@Nov 13 2004, 04:38 PM
I have a few minor quibbles with what you've written.

One is the paragraph . . . most of the particles in the disk that eventually accreted in to larger object cooled very rapidly.

My other quibble is in the statement as though it were fact that the lower mantle is primitive.
Right, Anton.

1. The surface/volume ratio decreases as the early condensates accrete together to form larger bodies. E.g., pueudo-meteorites -> asteroids -> planets

Geochemical measurements on planet Earth show that accretion occurred and the upper mantle melted to form the crust, the atmosphere, and the oceans before extinct I-129 and Pu-244 had decayed away.

2. The lower mantle has retained primordial He-3, Neon, and is more primitive than the upper mantle. There is no way iron could have moved through the lower mantle to form the Earth's core.

Interestingly, large iron meteorites contain decay products of extinct elements and unmixed isotopes from nucleosynthesis reactions. I suspect the same would be found in the Earth's core, but there is way to access that material.

With kind regards,

Oliver
http://www.umr.edu/~om

alainprice
2004-Nov-13, 06:48 PM
What process allows heavier elements to sink?

Buoyancy!!!

It's really only denser materials that can sink, not heavier ones.

damienpaul
2004-Nov-13, 06:50 PM
and i am definitely ain't going to the stinkin' core to find out!!!!

Duane
2004-Nov-13, 07:14 PM
Dr Manuel is simply wrong. His method does not account for the collision of the proto-earth with the Mars-sized body that formed the Earth, he ignores years of research into the seismic studies of the deep interior of this planet, and he dogmatically sticks to the method he employs of saying "I say it is true, for proof look at my work where I say it is true".

I also have training in geology and have studied reams of data arising from seismic waves initiated by surface and sub-surface explosions while searching for oil over most of northwestern Canada, including the arctic.

S-wave and P-wave studies of the deep interior identify not only deep-seated plumes rising from and sinking to the core/mantle boundry, they also identify an area of stiffness marking that boundry. The stiffness is the settling out of heavier material from the molten, differencitiated, recycling mantle.

The means by which the Earth and sun formed are completely different, as any nuclearphysicist or solar-physicist knows. Dr Manuel is a nuclear-chemist, not physicist, and his views of accretion, neutron degeneration, and every other aspect of nuclear physics is coloured by his perceptions of chemical reaction.

He is wrong about the Earth's formation, he is wrong about the Earth's makeup, he is wrong about the Sun's formation, and he is wrong about the makeup of the sun.

Planetwatcher
2004-Nov-13, 08:36 PM
If that happened, heavier elements would sink and accumulate in the interior of the Sun.
I find that a little hard to swallow.
At such a phase of development, there is nothing to sink to. No real center of gravity to speak of. If there was, there would be no accredition.
This kind of reasoning can only come from a person who believes the Iron Sun theory.

But if the whole works were spinning, and especially if doing so rapidly, then the heavier elements would move toward the outer parts of the disk, where the planets would form, and the lighter elements would tend to move toward the center. Where gravity would attract them to each other, begin to heat up by friction, and eventually ignite a fussion reaction, thus giving birth to a protostar.

Meanwhile, the heavier elements farther out in the disk are also attracted by gravity, clumping together to eventually become planets.

But now how one could form so quickly,
Perhaps there were a lot of very big clumps to begin with which would have cut down the time of formation.

Victoria
2004-Nov-13, 10:59 PM
So...antioseb says( if I get it :P ), planets form in the way of collection and not entirely in the form of material. Great Post. :)

om@umr.edu
2004-Nov-14, 05:33 AM
Originally posted by damienpaul@Nov 13 2004, 06:19 PM
Hey wait a sec, how do you know that there is He-3 in the bottom of the mantle?????
Damienpaul.

We know the depleted upper mantle is rich in radiogenic isotopes.

Xe-129 from the decay of extinct I-129
He-4 from the decay of U and Th
Ar-40 from the decay of K-40
Xe-136 from the decay of extinct Pu-244

Accompanying those radiogenic isotopes in mid-ocean ridge basalts are primordial He-3 and traces of primordial Ne.

The reasons for attributing He-3 and Ne to gases leaking from the undepleted lower mantle are explained in detail in:

"The Noble Gas Record of the Terrestrial Planets"

http://web.umr.edu/~om/archive/NobleGas.pdf

With kind regards,

Oliver
http://www.umr.edu/~om

damienpaul
2004-Nov-14, 06:25 AM
ah i see, yes the mid ocean ridges are indeed the logical place for detection, as are hotspots i'd assume (i could be wrong there).

So the way i see it, the way that He-3 gets to the surface is through the convection detected by seismic data that myself and my colleagues and Duane and his colleagues independently observed (as with countless multitudes no doubt).

this is very interesting indeed.

antoniseb
2004-Nov-14, 12:12 PM
Originally posted by om@umr.edu@Nov 14 2004, 05:33 AM
We know the depleted upper mantle is rich in radiogenic isotopes.
This paper starts off with an assumption that I don't completely accept:

The Earth’s atmosphere was produced by exhaustive degassing of the upper mantle during the first 200My
I think it is very likely that the Earth started with a huge atmosphere picked up during the accretion process, and that most of that atmosphere has boiled away during the first billion years, especially during the moon-forming event. A comparison of the isotope abundances in the ISM, Jupiter, and the Photosphere of the sun support this model. I can't guess where your idea came from.

So this paper makes some odd interpretations of the meaning of the isotope ratio differences observed in the air, the oceans, and volcanic venting. On the very positive side, if you ignore the conclusions, there is a lot of very nice data collection here, making it worth plowing through the 40 or so pages. Thanks for putting it online.

(Q)
2004-Nov-14, 03:02 PM
Oliver,

You have conveniently ignored my question, one of many that could make or break your pet theory.

What mechanism causes the heavier elements to 'sink?'

om@umr.edu
2004-Nov-14, 06:23 PM
Sorry, (Q).

I thought someone else replied.

Gravity would cause heavy elements to sink to the core of the Sun if it formed by accreting material.

The standard solar model (SSM) assumes the inside of the Sun initially had the same composition as its surface. Thus the SSM claims that Sun did not form by accreting material.

With kind regards,

Oliver
http://www.umr.edu/~om

(Q)
2004-Nov-14, 06:32 PM
Gravity would cause heavy elements to sink to the core of the Sun if it formed by accreting material.

One would first have to presume a core existed in order for gravity to cause the heavy elements to 'sink?'

Haven't you in fact put the cart before the horse?

om@umr.edu
2004-Nov-14, 07:21 PM
No.

The center of gravity exists, with or without a core.

Oliver

(Q)
2004-Nov-14, 08:11 PM
The center of gravity exists, with or without a core.

Too funny, Oliver. Gravity exists where matter does not.

You really should study physics before making claims.

kashi
2004-Nov-14, 11:54 PM
Yes sir Oliver...I'd like for you to answer that question.

Duane
2004-Nov-16, 06:01 PM
The standard solar model (SSM) assumes the inside of the Sun initially had the same composition as its surface. Thus the SSM claims that Sun did not form by accreting material.


Pardon? So how does the sun gather enough material to initiate nuclear fusion? Me think thou art reading thine textbooks askewed.

Duane
2004-Nov-16, 07:32 PM
After reading through Dr Manuel's suggestion for the SSM along with updates for the model up to 2001, I think I have finally discovered Dr Manuel's basis for the statement "assumes the inside of the Sun initially had the same composition as its surface".

You see, the SSM takes the sun from the approximate point where the sun begins its life in the main sequence, and carries forward from there. So, while Dr Manuel is sort of correct in saying that the SSM does not describe the sun accreting material, the statement is very misleading, in that it is assumed in the model that the sun has already accreted.

Having said that, there is no basis for the statement that "the SSM claims that Sun did not form by accreting material". In this, Dr Manuel has simply misunderstood the model.

om@umr.edu
2004-Nov-16, 08:03 PM
The Standard Solar Model "assumes a complete spherical symmetry, no mass loss or mass accretion, no angular momentum gain or loss, no differential rotation, and a zero magnetic field through the entire solar evolution."

Arnon Dar and Giora Shaviv, The Astrophysical Journal 468 (1996) page 935.

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2004-Nov-16, 08:14 PM
Dear Dr Manuel: Please advise, did you take the time to look at the link to the updated solar model I linked to? It is in the Questions and Answers forum. If not, would you be so kind as to do so?

Quoting from the paper:


Over the past four decades, the accuracy with which
solar models are calculated has been steadily refined as the
result of increased observational and experimental information
about the input parameters (such as nuclear reaction
rates and the surface of abundances of different elements),
more accurate calculations of constituent quantities (such
as radiative opacity and equation of state), the inclusion of
new physical effects (such as element difusion), and the
development of faster computers and more precise stellar
evolution codes.

Five years of very detailed studies of the sun make a huge difference.

Also:


We publish for the
first time the results of a precision calculation with the standard
solar model of the electron density throughout the
Sun, from the innermost regions of the solar core to the
solar atmosphere. We also present for the first time a
detailed calculation of the radial profile of the number
density of scatterers of sterile neutrinos. These quantities
are important for precision studies of neutrino oscillations
using solar neutrinos.
We also provide detailed predictions for the time evolution
of some of the important solar characteristics such as
the depth and mass of the solar convective zone; the radius
and the luminosity of the Sun; the central temperature,
density, pressure, and hydrogen mass fraction ; as well as the
temperature, density, pressure, and radiative opacity at the
base of the convective zone. As far as we know, these are the
first detailed results submitted for publication on the time
evolution of many of these quantities.

Duane
2004-Nov-16, 09:04 PM
Originally posted by om@umr.edu@Nov 16 2004, 08:03 PM
no mass loss or mass accretion,

Arnon Dar and Giora Shaviv, The Astrophysical Journal 468 (1996) page 935.


Well again, Dr Manuel, you appear to misunderstand the authors intent as it relates to the SSM. The idea is that the sun has already accreted and the old model you are referring to did not account for any further mass increase or decrease from the point where the sun entered the main sequence.

It does not mean or imply that:


Thus the SSM claims that Sun did not form by accreting material.


On the contrary, it is accepted that the sun accreted its material to the point where nuclear fusion took over. The SSM carries forward from when the sun settled into it's main sequence phase.

Greg
2004-Nov-16, 10:18 PM
I like the idea that planets can begin forming at the same time as the star. Of course we cannot have seen the system before the star began nuclear fusion to produce the photons that we see. But how much time could have passed from when the disc formed and the star ignited. Hopefully the Spitzer scope will shed some "light" on this question in the near future. If it is a significant period of time then why couldn't a planet have begun forming as soon as the disc formed (and before the star ignited)? Maybe it isn't necessary to rewrite the planet formation theories just yet.
The planet in question is very likely to be a gas giant and to me it seems that the evidence is weighing towards the fact that these can form without a "terrestrial" core of an accreted planetoid to build upon which had been the dominant theory in the past. The jury is still out on exactly how terrestrial planets like Earth are formed. Some of Oliver's ideas are worth considering as radio-isotopes should be significantly factored in when trying to piece the puzzle together. Unfortunately we have too few pieces of the puzzle to say for sure and the pieces we really would like ot have are buried under miles and miles of crust and mantle. The Russians did try to dig a hole down there but as expected could not get very far due to heat and pressure problems.

om@umr.edu
2004-Nov-17, 09:26 AM
Originally posted by Duane@Nov 16 2004, 08:14 PM
Dear Dr Manuel: Please advise, did you take the time to look at the link to the updated solar model I linked to?
Does the the "updated" Standard Solar Model now claim the Sun formed by accretion?

Perhaps the "more newer, latested revised, updated" Standard Solar Model will?

Of course the Sun formed by accretion, but

Accretion is incompatible with a homogeneous Sun, Duane. Gravitational segregation would sink heavy elements and enrich light elements at the solar surface during accretion.

Elemental segregation is observed in the Sun, but the observations are incompatible with the Standard Solar Model.

With kind regards,

Oliver
http://www.umr.edu/~om

Guest
2004-Nov-17, 10:46 AM
Planets forming from stars as ejection phenomena is much simplier model.It will take billions of years to form planet with accreation, yet planet in question is only 0,5 million y. old.
Model of "catching" planets from other stars or star explosions can't explain their positions (in a plain).

GOURDHEAD
2004-Nov-17, 12:38 PM
We also present for the first time a detailed calculation of the radial profile of the number density of scatterers of sterile neutrinos.
What are sterile neutrinos?

GOURDHEAD
2004-Nov-17, 01:35 PM
It seems to me that the complexity of the dynamics of the "set of collapsing profiles" for proto-stellar clouds would make their modeling extremely difficult. This is due to the very large range for the permutations and combinations of the following semi-independently variable yet coupled parameters. I don't claim to know all of them.
1. The number of separately collapsing stellar level partitions and the interplay
between them.
2. Initial angular momentum and the subsequent exchanges of angular
momenta between the stellar-sized pieces of the initial cloud.
3. The stochastic characteristics of the thermodynamics of collapse and the
thermal capacity of the ingredients (i.e., how much water).
4. The configurations and relative strengths of the randomly varying
number and strengths of the magnetic and electric fields of the separately
collapsing sections.
5. The number and strength of the jets of expelled material caused by the
heating due to collapse.

It seems that due to the wide ranging variability and methods of combining and permuting these characteristics, one should not be overly surprised at neither the size nor number of pieces of the resulting configuration.

antoniseb
2004-Nov-17, 02:14 PM
Originally posted by GOURDHEAD@Nov 17 2004, 01:35 PM
due to the wide ranging variability and methods of combining and permuting these characteristics, one should not be overly surprised at neither the size nor number of pieces of the resulting configuration.
The SKA should be able to make some observations that will help to constrain some of these free parameters, but yes, there is every reason to believe that variety is likely when it comes to the formation of planetary systems.

(Q)
2004-Nov-17, 03:06 PM
Gravitational segregation would sink heavy elements and enrich light elements at the solar surface during accretion.

Unfortunately, you make this claim without knowing anything about gravity, therefore we can only assume you made it up from your imagination.

Once again, you assume gravity exists where matter does not.

bobby
2004-Nov-17, 11:10 PM
ok could this work what if this was a three star set up the smaller of the three explodes knocking one of the others out but leaving enough matter to form the planet

Mike525
2004-Nov-18, 04:14 AM
Originally posted by Duane@Nov 13 2004, 05:15 PM

Seismic data doesn't tell us it hasn't been reworked.

In fact, seismic studies of s and p-wave propagation through the mantle and core has revealed areas of upwelling called "superplumes" that come from the base of the lower mantle at the core and rise all the way up to the lithosphere

Get it straight people--the mantle is not only melted throughout, it recycles. Furthermore, the lower mantle is not primitive--it can't be, because it recycles!
Duane,

I used your link and read the article and they make no sweeping assumption that all of the mantle is melted throughout. The fact that they detect plumes indicates channels for these plumes to flow through and therefore the likelihood of solid structures surrounding the plumes.

Correct me if I'm wrong.

Mike

om@umr.edu
2004-Nov-18, 05:11 AM
Mike525,

I know of nobody in the field of stable isotope geochemistry who believes that all of the mantle is melted throughout.

After Dr. Dwarka Das Sabu and I published our conclusion that the outer part of the Earth melted to produce the depleted upper mantle, crust, oceans, and atmosphere ["The Noble Gas Record of the Terrestrial Planets", Geochemical Journal (1980)]

http://web.umr.edu/~om/archive/NobleGas.pdf

several other research groups came to a similar conclusion. As I recall, the French group headed by Professor Claude Allegre was one of those.

There is little doubt that the upper mantle is highly depleted. There is also little doubt that primordial He is coming up from somewhere.

With kind regards,

Oliver
http://www.umr.edu/~om

Greg
2004-Nov-18, 09:15 AM
I do not think the models for mantle composition has changed much since I last studied geology. My understanding is that the upper mantle gets recycled from plate tectonics. Oceanic crust is subducted into the upper mantle continuously mixing the upper mantle rock with oceanic crust. The process occuring at ridges is less clear with regards to how deep down the material is coming from. Unlike the aforementioned plumes, oceanic ridges are thought to emanate from the lower mantle if I recall correctly.
The lowest portion of the lower mantle also is thought to get recycled via convection currents emanating from the core into the lower mantle and back down again. Thus the middle of the mantle is probably relatively pristine material left over from the Earth's formation. If only we could get down there to sample it.

To address the last post on a solar system capturing planets: The space between stars is quite vast. It is a vast desert with lots and lots of room for various objects. Yes there are probably lots of ejected planets out there but the chances of any solar system interacting with one are about equal to me being able to locate a single lightbulb of your choice in the city of Los Angeles without giving me a single clue which one you have picked. Of course things change if you refer to a globular cluster. Stars are so tightly packed there that the kind of thing you are referring to could occur routinely.

damienpaul
2004-Nov-18, 10:30 AM
your description of the mantle is how i understand it as well, Greg.

Dr. M. just a question, could the primordial material (is that the stuff measured at mid ocean ridges and volcanoes etc?) could it be possible that this material is coming from the Mantle-Outer Core boundary? or the Outer core itself?

om@umr.edu
2004-Nov-18, 03:21 PM
I forgot to mention one important event in the formation of rocky planets.

Dust apparently formed in the early planetary system.

Then it was suddenly melted, or partially melted, by flash heating.

The product was aerodynamically shaped into the spherically shaped chondrules that are abundant in chondritic (stone) meteorites.

We do not know if material in the giant gaseous planets experienced this event.

We suspect the flash heating occurred when the Sun ignited.

With kind regards,

Oliver
http://www/umr.edu/~om

Duane
2004-Nov-20, 12:01 AM
I know of nobody in the field of stable isotope geochemistry who believes that all of the mantle is melted throughout.


This is a riduculous statement. I know of nobody in the field of nuclear chemistry who believes the sun has an iron core either. So what!


several other research groups came to a similar conclusion. As I recall, the French group headed by Professor Claude Allegre was one of those.


I previously linked to an article written by Professor Allegre, where he says the core and mantle are melted and differentiated. Here it is again:

The Evolution of the Earth (http://www.physics.purdue.edu/astr263l/lecture_links/evolution/evolution.html)

You recall incorrectly.


The lowest portion of the lower mantle also is thought to get recycled via convection currents emanating from the core into the lower mantle and back down again. Thus the middle of the mantle is probably relatively pristine material left over from the Earth's formation. If only we could get down there to sample it.


Greg, the s&p-wave seismic studies being done over the last several years indicate that the super-plumes are rising from the mantle-core boundry. The convection seems to entail the entire mantle, from just below the lithosphere to the iron core. There may be smaller convections as well, but the seismic studies don't seem to show any.

om@umr.edu
2004-Nov-21, 06:18 PM
I will try to look up the reference to the paper by Professor Claude Allegre's research group and post the reference here.

As I recall, their conclusions were very much like those reached by Professor Dwarka Das Sabu and I in "The Noble Gas Record of the Terrestrial Planets"

http://web.umr.edu/~om/archive/NobleGas.pdf

With kind regards,

Oliver
http://www.umr.edu/~om

(Q)
2004-Nov-21, 07:08 PM
I know of nobody in the field of stable isotope geochemistry who believes that all of the mantle is melted throughout.

I know of nobody in the field of physics who would accept an iron core sun based simply on General Relativity.

Unfortunately, Oliver is unable to explain that one.

As I recall, their conclusions were very much like those reached by Professor Dwarka Das Sabu and I

Why do you always reference your website? It is ludicrous to presume your claims are substantiated solely on your conclusions.

VanderL
2004-Nov-21, 11:29 PM
Q:
I know of nobody in the field of physics who would accept an iron core sun based simply on General Relativity.

I didn't know General Relativity favoured an Iron Sun model. :huh:

Cheers.

(Q)
2004-Nov-22, 12:43 AM
It doesn't.

:rolleyes:

Mike525
2004-Nov-22, 12:50 AM
If you think you're ready for a paradigm shift in regards to this
issue check out D. B Larson's works (http://www.reciprocalsystem.com) which describes stellar formation and the more logically consistent process of energy generation in stars that allows for heavier elements in the core to reach their thermal limits and convert potential energy into kinetic (thermal).

BTW, accretion is taking place on our sun (esp. since our system is presently in a dust cloud region) and heavier elements naturally migrate towards the center of the sun and the lighter elements ie hydrogen stay in the outer---a gravitationally consistent density gradient so therefore hydrogen is not at the center region of the sun.

Please let me know what you think of this model after you read and mull over it.

Mike

om@umr.edu
2004-Nov-22, 05:01 AM
Below is the abstract of the paper by Professor Claude J. Allegre et al. "Constraints on Evolution of Earth's Mantle from Rare Gas Systematics", Nature 303 (1983) pages 762-766.

"Analyses of the isotopic composition of He, Ar and Xe in a suite of glasses from the mid-ocean ridges and from the island of Hawaii show that the Hawaiian samples have systematically lower He-4/He-3, Ar-40/Ar-36 and Xe-129/Xe-130 ratios than the mid-ocean ridge basalts.

We interpret this result to imply the existence of an un-degassed mantle reservoir.

Given the isotopic variations, and the half lives of I-129 and K-40 (parent isotopes of Xe-129 and Ar-40), the un-degassed reservoir must have been separated from the MORB source reservoir at least 4,400 Myr ago.

The most reasonable explanation for the data is therefore the existence of a two-layered mantle.

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2004-Nov-22, 07:35 PM
Excellent, a 20 year old paper written at a time when s &p wave studies were in their infancy. Sadly, typical. I think I will read a few papers from Allegre et al and see what they have to say now.

om@umr.edu
2004-Nov-27, 05:17 PM
Originally posted by damienpaul@Nov 18 2004, 10:30 AM
Dr. M. just a question, could the primordial material (is that the stuff measured at mid ocean ridges and volcanoes etc?) could it be possible that this material is coming from the Mantle-Outer Core boundary?
Hi, Damienpaul.

As I recall (I'm at home; reprints are in my university office), the non-radiogenic, primordial gases like He-3, Ne-20, Ar-36, Xe-130 come from deep plumes under Hawaii and Iceland.

Gases from the upper mantle have a higher (radiogenic)/(primordial) ratio, e.g., He-4/He-3, Ar-40/Ar-36, Xe-129/Xe-130.

Marvin Herndon has an alternative suggestion for one of these: He-3 may be the decay product of H-3 produced in a reactor at the Earth's core.

These gases probably come from the undepleted, lower mantle. Primordial He-3 also continually leaks into the depleted upper mantle from there.

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2004-Nov-27, 07:23 PM
I think I will read a few papers from Allegre et al and see what they have to say now.

Unfortunantly, Allegre hasn't done any recent studies, as he is too busy in France's political enviroment. C'est la vie!

The deep mantle studies being done by Jeroen Ritsema at CIT, Pasedena have confirmed the superplume of material rising from the core/mantle boundry (CMB) to the area of the east rift valley of Africa. The plume is clearly rising from the CMB as evidenced by the various s-wave timing event studies from various seismic events between 1980 and 1998 (STRUCTURE OF THE AFRICAN SUPERPLUME, (http://deep.asu.edu/previous/2002_spring/pdf/2002_Ritsema_SPconf.pdf) Jeroen Ritsema
Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA)

Further, the traditionally inferred mantle reservoirs once thought responsible for mid-ocean islands and ridges, while meeting geochemical constraints, are not able to account for the observed geophysical conditions. David Bercovici & Shun-ichiro Karato of the Department of Geology and Geophysics at Yale have proposed that chemical differences between basalts at mid-ocean ridges vrs those of plate hotspots such as Hawaii and recent tomographic studies (see, for example, Masters, G., Laske, G., Bolton, H. & Dziewonski, A. in Earth’s Deep Interior (eds Karato, S., Forte, A.,
Liebermann, R., Masters, G. & Stixrude, L.) 63–87 (AGU, Washington DC, 2000).)suggest that the subducting plates extend well into the deep mantle, likely as far as the CMB. This also suggests that there is likely little differencial layering of the mantle, such that the whole of the mantle convects. (Whole-mantle convection and the transition-zone water filter. (http://deep.asu.edu/previous/2004_spring/readings/2003_Bercovici_Nature.pdf) David Bercovici & Shun-ichiro Karato
Department of Geology and Geophysics, Yale University)

Other studies, principally p-wave studies by Montelli et al, have identified at least six well resolved plumes that extend all the way to the CMB. These same studies resolved and confirmed deep lithospheric slab intrusions into the lower mantle at various subduction zones around the Pacific basin, again suggesting deep mantle convection from the CMB to the lithosphere. (Finite-Frequency Tomography Reveals a Variety of Plumes in the Mantle Raffaella Montelli,1* Guust Nolet,1 F. A. Dahlen,1 Guy Masters,2
E. Robert Engdahl,3 Shu-Huei Hung4 (Science Magazine, Vol 303, Pgs 338-343, 16Jan2004))

There is more. The short story is that the mantle is not only clearly melted and differentiated throughout, it also recycles. What say you Dr Manuel?

om@umr.edu
2004-Nov-27, 07:47 PM
Originally posted by Duane@Nov 27 2004, 07:23 PM
The short story is that the mantle is not only clearly melted and differentiated throughout, it also recycles.
Poppycock!

Primordial heterogeneities have been preserved within the Earth.

If the mantle "melted and differentiated throughout", it would be mixed.

Primordial gases like He-3 would have escaped.

Primordial He-3 would not still be linked with primordial Ne-20, Ar-36, Xe-130.

We would not see regions with high Xe-129/Xe-130 from the decay of extinct I-129 in the early history of the Earth.

Four billion yr later, high Xe-129/Xe-130 ratios would not be linked with high Ar-40/Ar-36 ratios.

Measurements clearly show the mantle is not "melted and differentiated throughout".

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2004-Nov-27, 07:50 PM
Another article that I think is impotant to this discussion is Recycled Dehydrated Lithosphere Observed in plume-influenced mid-ocean ridge basalt (http://deep.asu.edu/previous/2004_spring/readings/2002_Dixon_Nature.pdf) Jacqueline Eaby Dixon, Loretta Leist, Charles Langmuir & Jean-Guy Schilling Nature Vol 420, Nov 2002, Pgs 384-389.


HIMU is believed to represent recycled, old,
hydrothermally altered oceanic crust, dehydrated and metamorphosed
to eclogite during subduction. HIMU sources are depleted
in Pb and K and enriched in U, Nb and Ta (refs 10, 11) relative to
MORB. EM1 includes either recycled oceanic crust plus a few per
cent pelagic sediment10–12 or metasomatized subcontinental lithosphere13.
EM2 includes recycled oceanic crust containing a few per
cent of continent-derived sediment11.

antoniseb
2004-Nov-27, 07:51 PM
Originally posted by Duane@Nov 27 2004, 07:23 PM
The short story is that the mantle is not only clearly melted and differentiated throughout, it also recycles.
As a further clarification, if the information is handy, Dr. Manuel's point was based on research that there were different isotope ratios of the gasses being emitted from these various volcanic locations, and it was this variation that he was using to claim that the so-called upper mantle had been depleted, and the alleged lower mantle and core had not been depleted of these gasses.

Do we have some recent paper with a chart relating gas isotopes to apparent plume depth? It's worth checking to see if the ratios are not globally constant for given depths.

Duane
2004-Nov-27, 07:59 PM
Poppycock!

Primordial heterogeneities have been preserved within the Earth.

If the mantle "melted and differentiated throughout", it would be mixed.


Ok OM, please take a moment to enlighten the good readers of this forum as to how there could be measured and observed intrusions of lithosphere slabs in the deep mantle, penetrating to the CMB and some six clearly identified superplumes of material extending from the CMB to the lithosphere if the mantle is not melted?

If you accept that the mantle is melted, then perhaps you could go on to enlighten the good readers of this forum as to how the mantle could remain undifferentiated.

Would you also be so kind as to explain the observed stiffness at the core-mantle boundry that is thought by geologists to be material that has settled out of the mantle?

om@umr.edu
2004-Nov-27, 08:14 PM
As noted above,

Primordial heterogeneities have been preserved within the Earth for billions of years !

Heterogeneities observed yesterday, last week, last year, last decade, or 33 years ago do not need to be confirmed by newer measurements !

In 1970 I personally drove to New Mexico and collected samples of carbon dioxide gas from the Earth's upper mantle in carefully evacuated, cleaned cylinders.

Excess Xe-129 from the decay of extinct I-129 in the Earth was observed. See Science:

http://web.umr.edu/~om/archive/XenonRecord.pdf

Samples of that gas went to several leading research groups, including John Reynolds in Berkeley and Paul Kuroda in Fayetteville. Both groups confirmed radiogenic Xe-129 inside the Earth.

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2004-Nov-27, 08:22 PM
As noted above,

Primordial heterogeneities have been preserved within the Earth for billions of years !


I'm sorry but I don't see what difference that makes. You got 1 reading from 1 site 30 years ago, and then extrapolate that to suggest the lower mantle is unmelted? What about the studies I have linked to above?

Please OM, try answering the questions.

Recent s and p wave studies of the mantle have clearly shown areas where the subducting lithosphere extends into the lower mantle, all the way to the CMB. They have also shown other areas where superplumes of material rise from the CMB all the way to the lithosphere.

Is your avoidance of the questions a responce to your inability to believe the reseachers I have cited here? Are you saying their findings are wrong? Is it that you don't understand what they are saying? Are you so certain of your evidence that you cannot look at what others are doing? Are you too proud to admit that you might be incorrect?

Please Oliver, explain this to me. You shout your certainty, but you don't acknowledge any of the research shown in the links I have provided above, and you don't answer the questions.

Did you know it is ok to say "I don't know"? Maybe if you admit that, we can begin to construct a theory that explains both your chemical findings and the seismic findings. Take a breath man, you're going to give yourself a heart attack.

Duane
2004-Nov-27, 08:25 PM
Do we have some recent paper with a chart relating gas isotopes to apparent plume depth? It's worth checking to see if the ratios are not globally constant for given depths

Man, there is so much out there on seismic, mantle, isotope etc studies, there must be something somewhere. Too much to look through for moi.

om@umr.edu
2004-Nov-27, 09:27 PM
Originally posted by Duane@Nov 27 2004, 08:22 PM

As noted above,

Primordial heterogeneities have been preserved within the Earth for billions of years !


I'm sorry but I don't see what difference that makes.
I understand, Duane.

I will try once more.

Ask yourself how "Primordial heterogeneities have been preserved within the Earth for billions of years !",

since the time when 16 My I-129 and 82 My Pu-244 were alive and decaying, if as you claim

the mantle "melted and differentiated throughout".

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2004-Nov-27, 09:53 PM
Ask yourself how "Primordial heterogeneities have been preserved within the Earth for billions of years !",


Good question, especially in light of the geological studies done over the last 10 or so years, which use s and p wave propogation through the mantle to reveal that lithospheric slabs extend from zones of subduction down through the lower mantle, perhaps even to the CMB, and also show so-called "superplumes" of material rising in at least 6 distinct areas, from the CMB to the lithosphere.

Ok, I'll try this once more Oliver. These are my specific questions:

1) How can you explain how primordial herterogenities can be preserved in mantle samples when scientific evidence of s and p wave studies show that the mantle is completely melted throughout?

2) Furthermore, how can you explain how you got readings of primordial heterogeneties when s and p wave seismic studies show strong evidence of mantle recycling as evidenced by observed slabs of lithospheric intrusion into the deep mantle, and observed plumes of material rising from the core-mantle boundary to the lithosphere?

Oliver, please answer these specific questions. You do not have to repeat that you got the readings--we know that, you have already said it three times in this thread.

Copy the question and answer it!

om@umr.edu
2004-Nov-27, 11:53 PM
Originally posted by Duane+Nov 27 2004, 09:53 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Duane &#064; Nov 27 2004, 09:53 PM)</td></tr><tr><td id='QUOTE'> 1) How can you explain how primordial herterogenities can be preserved in mantle samples when scientific evidence of s and p wave studies show that the mantle is completely melted throughout? [/b]
1a.) In some but not all regions of the mantle, we observe excess radiogenic decay products, Xe-129 and Xe-136, from extinct elements that have been gone for billions of years. Decay products of long-lived elements, K-40 and U-238, accumulated in these same regions.

1b.) In some but not all regions of the mantle, we observe more primordial gases, like He-3, Ne-20, Ar-36, and Xe-130. The decay products of short-lived elements, like I-129 and Pu-244, and long-lived elements, K-40 and U-238, are less prominate in these regions.

<!--QuoteBegin-Duane@Nov 27 2004, 09:53 PM
2) Furthermore, how can you explain how you got readings of primordial heterogeneties when s and p wave seismic studies show strong evidence of mantle recycling as evidenced by observed slabs of lithospheric intrusion into the deep mantle, and observed plumes of material rising from the core-mantle boundary to the lithosphere? [/quote]
2a.) Seismology is like shaking something and listening to it rattle. It is not a great analytical tool. If you read carefully, you will probably find statements like "slabs of the lithospheric may have intruded into the deep mantle."

2b.) I doubt if any analytical lab anywhere uses sound waves to determine chemical make-up.

A lot of analytical chemists would be unemployed if sound wave transmission gave the chemical composition.

With kind regards,

Oliver
http://www.umr.edu/~om

PS - Heck, Duane, primordial heterogeneities are observed in noble gases. Gaseous elements would be the first to mix if the mantle "melted and differentiated throughout".

It just didn&#39;t happen.

Duane
2004-Nov-28, 11:40 AM
Seismology is like shaking something and listening to it rattle. It is not a great analytical tool. If you read carefully, you will probably find statements like "slabs of the lithospheric may have intruded into the deep mantle."


Interesting. So you are saying that the studies I&#39;ve linked to and the authors of those studies are wrong then. Is that correct?

I have read therm carefully Dr M, they do not say "may have intruded into the deep mantle" they say "have intruded into the deep mantle and may even have reached the CMB".


2b.) I doubt if any analytical lab anywhere uses sound waves to determine chemical make-up.


Me too. Who said that was being done?


Heck, Duane, primordial heterogeneities are observed in noble gases. Gaseous elements would be the first to mix if the mantle "melted and differentiated throughout".


Heck Oliver, distinct superplumes of material are observed to rise from the CMB to the lithosphere, and lithospheric slabs are observed to extend into the deep mantle.

So again Oliver, if "we" observe primordial heterogenities, how is it that "we" also observe the plumes and intrusions?

We are going around in circles here. Surely there must be an answer that does not require you to simply restate what you observed. The plumes and intrusions are observed too Oliver, and by a whole pile of researchers. Did you read the links?

Or is it that you are saying they are all wrong?

om@umr.edu
2004-Nov-28, 05:36 PM
Hi, Duane.

Samples taken into the laboratory and analyzed show conclusively that heterogeneities have remained intact in the mantle over the history of the Earth, back to the time when extinct elements like I-129 and Pu-244 were alive and decaying.

With kind regards,

Oliver
http://www.umr.edu/~om

Duane
2004-Nov-29, 07:59 PM
Oliver, maybe it&#39;s me that isn&#39;t communicating. I say this because you are absolutely not answering the questions I am posing.

I&#39;ll again from a different angle.

In 1970 you found evidence of intact heteorgeneities as revealed by laboratory analysis and confirmed independantly by an outside lab to whom you provided samples. Ok, I accept that your analysis is correct.

You say that this proves that the lower mantle is unmelted and undifferentiated because the primordial heteorgeneities could not survive if the mantle was melted and mixed.

I say that this conclusion cannot be correct because of the multiple and ongoing studies of the mantle being conducted around the globe. Please allow me to explain my reasoning.

In the mid-eighties is was realized that seismic instruments around the world could be used to time the s and p waves generated by earthquakes. These waves propagate through the Earth&#39;s mantle, slowing or speeding up through different materials and different temperature zones in a well understood and measured way.

Since 1985 the number of siesmic instuments around the world has been tripled, their sensitivity has been doubled (or more), and they have been placed in regions of the world where they never were before.

Since 1988 the s and p waves of something like 1100 seismic events have been measured.

The S and P Wave studies by a host of researchers in several countries and a couple of dozen universities have used the increasing number and sensitivity of seismic instruments to map the internal structure of the mantle between the lithosphere and the core-mantle boundry (CMB). Those maps have revealed at least 6 areas where gigantic plumes of material are measured to be rising, and have revealed the plumes begin at the CMB and rise through the mantle all of the way to the bottom of the lithosphere.

One such plume has been more extensively studied, and has been nick-named the African super-plume. Recent (2004) p-wave studies have shown that the plume rises in an east-leaning pattern that seems to correspond to it&#39;s being influenced by the Earth&#39;s rotation. Deeper p-wave sudies of other plumes are also showing that same type of influence.

Other deep wave studies have identified slabs of oceanic lithosphere that have penetrated into the deep mantle, and may, in fact, reach all of the way to the CMB.

The measured temperature and viscosity of the mantle combined with the measured and observed rising, moving superplumes and the sinking, deep penetrating oceanic lithospheric slabs clearly prove that the mantle is melted from the bottom of the lithosphere to the CMB. The evidence for this conclusion comes from many different sources, from accepted research papers running from 1988 to the present. I have linked to a very small sampling of such papers in this thread.

So my questions Oliver.

1) Do you accept that the s and p-wave studies are legitimate?

2) If not, why not?

3) If you accept that the wave studies are legitamite;

a) do you agree they have shown the superplumes are rising though the mantle?

and

B) Do you agree that they show the intrusion of the oceanic lithosphere into the deep (> 2500 miles) mantle.

4) If your answer to 3a &b is no, why not?

I hope you take the time to provide a real answer, and not just repeat that the primordial heterogenities "prove" you right. I also hope that you don&#39;t just dismiss this conversation.

Finally, I am starting a new topic under Alternative theories. (I probably should have done this responce there) Please post your responce there.