[meteorite-list] Supernova Shrapnel (weird NWA 2086 inclusion)

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Thu, 16 Sep 2010 11:10:39 -0400
Message-ID: <AANLkTi=nA8=x_aWjtsbOsKKsqN-BO7NZK6c3RKjaujgv_at_mail.gmail.com>

Hi Greg and List,

This is somewhat off-subject, but semi-related as well.

If the list will recall, I recently posted about an NWA 2086 stone
that I cut open, and it revealed a strange inclusion that is very
atypical of NWA 2086. Some list members had initial doubts about
whether the specimen was indeed 2086. Well, I have interesting news
about this stone.

I sent off a slice to a friend who is a qualified scientist at a major
university. I won't mention his name because I don't want him to get
inundated with submissions. Upon examining the stone in hand, he
agreed that the strange "inclusion within an inclusion" did not appear
to be weathering or terrestrialization. He hazarded a guess that the
inclusion might be some form of "star dust" or foreign meteoritic
material that accreted into the matrix during formation. Initially,
he was going to make a couple of thin-sections from the material and
make a visual analysis. But now he is very intrigued and is going to
put the specimen through the microprobe to get an elemental
composition. So, this is one of the mysteries that is going to be
solved soon, and I will share the answer with the list when the
results come in.

I'd like to thank Blaine Reed and Gary Fujihara for providing this
anomalous sample of NWA 2086 and my unnamed friend for kindly donating
his expertise and microprobe time in solving this meteoritic mystery.

And just for record, yes, this specimen is indeed NWA 2086. It's just
a very anomalous example of this meteorite.

And it's another example of something recently discussed on this list
- collectors and dealers, please do NOT alter your specimens with
foreign substances during processing. You never know when science may
come knocking on your door and want a pristine specimen.

Best regards,

MikeG

----------------------------------------------------------------------
Mike Gilmer - Galactic Stone & Ironworks Meteorites

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On 9/16/10, Greg Catterton <star_wars_collector at yahoo.com> wrote:
> Very cool info!
> Here is a pic of my Orgueil
> http://i27.photobucket.com/albums/c165/jedisdiamond/DSCF5360.jpg
>
>
> Greg Catterton
> www.wanderingstarmeteorites.com
> IMCA member 4682
> On Ebay: http://stores.shop.ebay.com/wanderingstarmeteorites
> On Facebook: http://www.facebook.com/WanderingStarMeteorites
>
>
> --- On Thu, 9/16/10, MEM <mstreman53 at yahoo.com> wrote:
>
>> From: MEM <mstreman53 at yahoo.com>
>> Subject: [meteorite-list] Supernova Shrapnel Found in Meteorite
>> To: "metlist" <meteorite-list at meteoritecentral.com>
>> Date: Thursday, September 16, 2010, 4:01 AM
>> Yet another meteorite related news
>> item. Check your specimens for chromium 54
>> grains and see if you've hit the lottery for pre-pre-solar
>> grains! They will be
>> magnetic but at 100 nm not somehting you'll see with the
>> eye alone.
>> Elton
>>
>> Supernova Shrapnel Found in Meteorite
>> ScienceDaily (Sep. 14, 2010) ? Scientists have identified
>> the microscopic
>> shrapnel of a nearby star that exploded just before
>> or during the birth of the
>> solar system 4.5 billion years ago.
>>
>> Faint traces of the supernova, found in a meteorite,
>> account for the mysterious
>>
>> variations in the chemical fingerprint of chromium
>> found from one planet and
>> meteorite to another. University of Chicago
>> cosmochemist Nicolas Dauphas and
>> eight co-authors report their finding in the late Sept. 10,
>> 2010 issue of the
>> Astrophysical Journal.
>> Scientists formerly believed that chromium 54 and other
>> elements and their
>> isotopic variations became evenly spread throughout the
>> cloud of gas and dust
>> that collapsed to form the solar system. "It was a
>> very well-mixed soup," said
>> Bradley Meyer, a professor of astronomy and astrophysics at
>> Clemson University
>> who was not a co-author of the study. "But it looks like
>> some of the
>> ingredients got in there and didn't get completely
>> homogenized, and that's a
>> pretty interesting result."
>> Scientists have known for four decades that a supernova
>> probably occurred
>> approximately 4.5 billion years ago, possibly triggering
>> the birth of the sun.
>> Their evidence: traces of aluminum 26 and iron 60,
>> two short-lived isotopes
>> found in meteorites but not on Earth.
>> These isotopes could have come from a type II supernova,
>> caused by the
>> core-collapse of a massive star. "It seems likely that at
>> least one massive
>> star contributed material to the solar system or what was
>> going to become the
>> solar system shortly before its birth," Meyer said.
>> Researchers have already extracted many type II supernova
>> grains from
>> meteorites, but never from a type IA supernova. The
>> latter type involves the
>> explosion of a small but extremely dense white-dwarf
>> star in a binary system,
>> one in which two stars orbit each other. It should
>> now be possible to determine
>>
>> which type of supernova contributed the chromium 54 to the
>> Orgueil meteorite.
>> "The test will be to measure calcium 48," Dauphas said.
>> "You can make it in
>> very large quantities in type Ia, but it's very difficult
>> to produce in type
>> II." So if the grains are highly enriched in calcium
>> 48, they no doubt came
>> from a type Ia supernova.
>> Cosmochemists have sought the carrier of chromium 54 for
>> the last 20 years but
>> only recently have instrumentation advances made it
>> possible to find it.
>> Dauphas's own quest began in 2002, when he began the
>> painstaking meteorite
>> sample-preparation process for the analysis he was
>> finally able to complete
>> only last year.
>> Dauphas and his associates spent three weeks searching for
>> chromium 54-enriched
>> nanoparticles with an ion probe at the California Institute
>> of Technology. "Time
>>
>> is very precious on those instruments and getting three
>> weeks of instrument time
>>
>> is not that easy," he said.
>> The researchers found a hint of an excess of the
>> chromium-54 isotope in their
>> first session, but as luck would have it, they had to
>> search 1,500 microscopic
>> grains of the Orgueil and Murchison meteorites before
>> finding just one with
>> definitely high levels.
>> The grain measured less than 100 nanometers in diameter --
>> 1,000 times smaller
>> than the diameter of a human hair. "This is smaller
>> than all the other kinds of
>>
>> presolar grains that have been documented before, except
>> for nanodiamonds that
>> have been found here at the University of Chicago," Dauphas
>> said.
>> The findings suggest that a supernova sprayed a mass of
>> finely grained
>> particles into the cloud of gas and dust that gave birth to
>> the solar system
>> 4.5 billion years ago. Dynamical processes in the
>> early solar system then
>> sorted these grains by size. These size-sorting
>> processes led the grains to
>> become disproportionally incorporated into the
>> meteorites and planets newly
>> forming around the sun.
>> "It's remarkable that you can look at an isotope like
>> chromium 54 and
>> potentially find out a whole lot about what happened in the
>> very first period
>> of the solar system's formation," Meyer said.
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--

Received on Thu 16 Sep 2010 11:10:39 AM PDT