[meteorite-list] Chondrule formation mechanism (Info Please)

From: Rob McCafferty <rob_mccafferty_at_meteoritecentral.com>
Date: Wed Oct 25 15:52:15 2006
Message-ID: <20061025195209.55474.qmail_at_web50913.mail.yahoo.com>

I suppose you are correct. I suspect the iron flecks
in chondrites must be stellar relics.

The iron is formed in the cores of all stars.
Nuclearly speaking it is the stablest of all elements
(lowest binding energy per neucleon...or is it the
highest, can't remember)
So as a consequence it is the final fusion product in
the cores of all stars which are heavy enough to get
that far (red dwarf stars aren't considered massive
enough to get beyond the helium burning phase).
However, only supernovae spread their innards out at
the end so every atom of iron was created by a
supernova as indeed was every atom that isn't
hydrogen, helium or lithium. All others are created in
stars. However, the atoms higher in the periodic table
cannot be made in stars as they require a net input of
energy to fuse whereas the lighter ones relase energy.
Only in a huge energy surplus can you manufacture
these higher elements. This is where the supernova
comes in. In that brief period where the star
aoutshines an entire galaxy, there is enough excess
energy to create quantities of elements up to Uranium
(and possibly beyond but non of these are stable).
This is a most wonderful process which not only
creates all the elements needed for life but also
seeds the universe with them.
And not a crackpot creationist theory involving
venting asteroids into space in sight.

As for the ages of the iron/nickel. I'm not sure if
ages are measured or if they can be. That'd be
interesting if they could. It's probable that our sun
and solar system are not even second or third
generation. The big stars last only a short period and
there's been a long time for the cycle to repeat a few
times.

Rob McC

--- Pete Pete <rsvp321_at_hotmail.com> wrote:

> Hi, all,
>
> This discussion about chondrules is fascinating!
>
> Hoping not to digress off this topic too much, but a
> question I have is
> about the metal flecks (not the later-formed iron
> meteorites) in any of the
> stonies.
>
> Have they ever been given an estimated age?
>
> If the heavy elements, such as nickel and iron, are
> created by a supernova,
> and the chondrules are in theory formed much later
> during the future
> dynamics of our solar system's nebula, would it be
> fair to say that the
> metal flecks would be billions and billions
> (apologies, Carl) of years OLDER
> than chondrules?
>
> And that they came from a distance much further than
> our solar system's
> vicinity?
>
> Considering that the supernova is exploding outward
> and the new elements'
> density is thinning out very quickly, wouldn't it be
> more likely that these
> iron and nickel flecks that eventually found a new
> home in our solar nebula
> and meteorites have come from more than one,
> probably a lot more, supernova?
>
> If so, why don't we see any remnants of any
> supernova explosion in our
> relative proximity? The Helix Nebula is the closest
> to us, at 450
> light-years!
>
http://images.google.ca/images?q=helix+nebula&hl=en&lr=&sa=X&oi=images&ct=title
>
> Not even a wisp left...
> Are tiny, but very dense, nebulas even possible? I
> can't imagine dust-bunny
> nebulae.
>
> If not, would it be unreasonable to expect that our
> planetary nebula could
> have extended out to Centauri, where our closest
> star neighbours are?
> When I dwell on the "Pillars of Creation" photos
> (Orion stellar-formation nebula,
>
http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/44/image/a)
>
> that describes a small point being comparable to the
> breadth of our solar
> system, ~4.3 light-years to Centauri isn't that
> far...
>
> Maybe the seldom-discussed/appreciated metal flecks
> are the real gems in the
> meteorites?
>
> Or, is the nebula in my head too dense that am I
> just missing something
> obvious?
> How is my logic flawed?
>
> Cheers,
> Pete
>
>
>
>
> From: Warin Roger <warinroger_at_yahoo.fr>
> To: "Sterling K. Webb"
>
<sterling_k_webb_at_sbcglobal.net>,meteorite-list@meteoritecentral.com
> CC: "E.P. Grondine" <epgrondine_at_yahoo.com>
> Subject: Re : [meteorite-list] Chondrule formation
> mechanism (Info Please)
> Date: Tue, 24 Oct 2006 16:15:53 +0000 (GMT)
>
> Hi, all,
>
> I am surprised that nobody evoked the theory
> following which chondrules were
> formed in relatively very few privileged zones of
> space. They would then
> form through one or more impacts of relatively large
> asteroids, onto the
> parent body covered with regoliths (and even with
> megaregoliths).
> The excellent book of Derek Sears, entitled ?The
> origin of chondrules and
> chondrites? (Cambridge Planetary Science, 2004)
> supports this hypothesis. In
> corollary, ordinary chondrites (85% on Earth) would
> be quite rare in cosmos,
> and only few parent bodies would produce chondrites.
>
> Glad to hear some comments on the above assumptions.
>
> Thanks,
>
> Roger Warin
>
>
>
> ----- Message d'origine ----
> De : Sterling K. Webb
> <sterling_k_webb_at_sbcglobal.net>
> ? : meteorite-list_at_meteoritecentral.com
> Cc : E.P. Grondine <epgrondine_at_yahoo.com>
> Envoy? le : Dimanche, 22 Octobre 2006, 20h38mn 55s
> Objet : Re: [meteorite-list] Chondrule formation
> mechanism (Info Please)
>
>
> Hi, Ed, Rob,
>
> This scenario (Ed's) would require that we
> would
> find a chondrule with a formation age of 3.9 Gya, I
> think. As far as I know, that has never happened.
>
> All chondrites (so called because they contain
> chondrules) are the same age: "about" 4.555 Gya.
> Chondrules are the same age (2 to 5 million years
> variation among chondrules) as the chondrites they
> occur in. The "about" is because the dating methods
> have a limit to how precisely they can resolve
> small age differences.
>
> Dating by lead isotopes says the solar system
> is 4.560 +/- 0.005 Gya old. Other systems of isotope
> measurements (like 147Sm/143Nd) give 4.553 +/-
> 0.003,
> and so forth. Within the limits of measurement, all
> chondrites are the same age, a hair younger than the
> solar system itself, the Class of Zero, and so are
> their
> chondrules.
>
> Meteorites that do not (never did) contain
> chondrules
> have varying ages. Lunaites are the age of that
> portion
> of the lunar crust they came from, generally quite
> old
> compared to Martians which have the "formation age"
> of the basalt flow they were chipped off of for the
> long
> haul to Earth. Irons, which formed inside a
> differentiating
> body, have younger ages; some very much younger if
> the differentiation took a long time (Weekeroo
> Station IIe
> is 4.340 Gya, Kodaikanal IIe 3.800 Gya, many IAB
> irons
> the same).
>
> I'm thinking that before you need to develop a
> theory
> to explain a 3.9 Gya chondrule, you'd have to
> actually
> have a 3.9 Gya chondrule. As far as I know, none
> with
> discordant ages have ever been found. In certain
> solar
> circles it would be Big News.
>
> Oddly, if you Google for "oldest chondrule,"
> you get
> the oldest chondrules, and if you Google for
> "youngest
> chondrule," you get the oldest chondrules... on the
> grounds
> that it is "young" as the solar system. If you
> Google for
> "discordant chondrule age," you get arguments over 2
> or 3
> million years in the age of something 4-1/2 billion
> years old.
>
>
> Sterling K. Webb
>
--------------------------------------------------------------------
> ----- Original Message -----
> From: "E.P. Grondine" <epgrondine_at_yahoo.com>
> To: <meteorite-list_at_meteoritecentral.com>
> Sent: Sunday, October 22, 2006 10:24 AM
> Subject: Re: [meteorite-list] Chondrule formation
> mechanism (Info Please)
>
>
> > Hi Rob -
> >
> > You noticed the contradiction in cooling periods
> as
> > well.
>
=== message truncated ===


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Received on Wed 25 Oct 2006 03:52:09 PM PDT