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Thread: Discussion: Baby Planet Puzzles Astronomers

  1. #31
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    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

  2. #32
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    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?

  3. #33
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    No.

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

    Oliver

  4. #34
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    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.

  5. #35
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    Yes sir Oliver...I'd like for you to answer that question.

  6. #36
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    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.

  7. #37
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    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.

  8. #38
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    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

  9. #39
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    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.

  10. #40
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    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.

  11. #41
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    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.

  12. #42
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    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

  13. #43
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    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).

  14. #44
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    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?

  15. #45
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    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.

  16. #46
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    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.
    Forming opinions as we speak

  17. #47
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    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.

  18. #48
    bobby Guest
    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

  19. #49
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    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

  20. #50
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    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

  21. #51
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    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.

  22. #52
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    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?

  23. #53
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    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

  24. #54
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    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

    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.

  25. #55
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    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

  26. #56
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    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.

  27. #57
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    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.

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    It doesn't.


  29. #59
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    If you think you're ready for a paradigm shift in regards to this
    issue check out D. B Larson's works 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

  30. #60
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    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

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