[meteorite-list] Some Minor Mammoth Corrections

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu, 13 Dec 2007 23:14:30 -0600
Message-ID: <087301c83e10$355fd190$5d22e146_at_ATARIENGINE>

Hi, Darren,

    Yes, there's nothing like supernova to bring out
the whackoes! Partly since they can claim almost
any effect they want to, as people are not that
familiar with supernovae. But they make a fine
super-scary hook on which to hang your private

    One correction to my first post: Beryllium-10 can
also be produced by cosmic rays (or any sufficient
energetic particles or nuclei). Rob Matson corrected
me on that two years ago: "Be10 is produced by cosmic
ray spallation of atmospheric nitrogen or oxygen;
similarly, I-129 can be produced by cosmic rays hitting
atmospheric xenon." Sorry, Rob, I'm a slow learner,
but I re-read my old email... So, Beryllium-10 is a
marker of a supernova, but not all of it is produced
that way. Iron-60 can only be made in a supernova.

    I also found some of my own old emails
about supernovae:

    Supernovae are the most ignored long-term
general threat the Earth faces, and that's a
    Part of the problem is that supernovae IN our
galaxy are obscured BY our Galaxy, it being a flat
disk of stars. For a long time, the estimate was
for three per century; newer analysis suggests that
one every 13 to 17 years is more like it. That means
that, by random chance distribution, every fifteen
million years or so, we would be within 50 light
years of one. That would not be good.
    As always, the important thing is location,
location, location, and that is NOT random. I
wish I could tell you that we live in a better
neighborhood, but the truth is, we're living in a
bad part of the galaxy.
    We're on the edge of a "star-forming region,"
which is just where supernovae happen. Since they're
NOT randomly distributed, our risk is much higher.
    You should look at:
    Nice respectable science from John Hopkins and
the NIH, which does a fine job of detailing our
dangerous position. I quote: "the Scorpius-
Centaurus association of hot young stars within
just a few hundred light-years of us has produced
about 20 supernova explosions within the past
10 million years."
    A little quick arithmetic with my fingers reveals
that's an average of one every half million years.
Worse, the motions of these stars may have brought
them closer in past years. Read the article in
Physics Today (link above).
    You may recall that a few years ago, a study,
after sifting through a huge muck of oceanic sediments
with a mass spectrometer, found twenty-three (yes, 23)
Fe60 atoms. Big deal, you say, 23 ATOMS, but
Fe60 doesn't occur "naturally;" it is only produced
in supernovae. They were all in one 2.8 million year
old sample of sediment, and they actually correspond
to a high flux, meaning we were way too close to a
Type II supernova back then.
    These authors suggest that it was a Sco-Cen
supernova and was responsible for a marine mini-
extinction event. You judge. In judging the article's
references to relative dangers of supernova, you should
bear in mind that supernovae come in different varieties
and the assertion that we could be undamaged by one as
close a ten light years is based on the tiniest variety.
    Other supernovae are much, much worse, releasing
10^53 ergs instantaneously, about 1000 times all the energy
that will produced by our Sun during its 10,000,000,000
year lifetime. Bad news. I'd like to see that, of course,
but from about 1000 light years away... You wouldn't want
front row seats. And anybody who thinks it would be OK
to be within 10 light years of that event, is just crazy.

    And this one:

    I looked into the work done to find that
handful of probably 5 million year old 60-Fe
atoms in oceanic sediments a few years ago,
and it was a monumental task, involving the
processing of a huge amount of material to find
a few atoms among the trillions of trillions of
atoms processed, like Madame Curie going through
tons of pitchblende to find some radium... It
took years, in both cases, really hard work.
This may be why there is no line of volunteers
going around the block to do this work on
Firestone's samples... The total number of
atoms found by the German team? 23.

    However, those 60-Fe atoms prove that we
were exposed to a major supernova explosion
that recently, a controversial suggestion now
nailed down, like, rock solid. Science is
hard work.

    Here's the poop on the 60-Fe atoms:
    "An interdisciplinary team of German
scientists from the Technical University
of Munich (Gunther Korschinek, 011-49-89-
289-14257,korschin at physik.tu-muenchen.de),
the Max-Planck Institute (Garching), and
the University of Kiel have identified
radioactive iron-60 atoms in an ocean
sediment layer from a seafloor site in
the South Pacific. First, several sediment
layers were dated, and only then were
samples scrutinized with accelerator mass
spectroscopy, needed to spot the faintly-
present iron. The half-life of Fe-60
(only 1.5 million years), the levels
detected in the sample, and the lack
of terrestrial sources point to a
relatively nearby and recent supernova
as the origin. How recent? Five million
years. How close? Close. An estimated 90
light years. If the supernova had been
any closer than this, it might have had
an impact on Earth's climate. The resear-
chers believe traces of the Fe-60 layer
(like the iridium layer that signaled
the coming of a dinosaur-killing meteor
65 million years ago) should be found
worldwide but have not yet been able
to search for it.
(K. Knie, W. Hillebrandt, et al., Physical
Review Letters, 5 July 1999.)"

    Or see this reference:

    The discovery has been variously haled
as "major, astonishing, compelling," and so

    Since then the same team has repeated their
results with greater precision:
    "Back then they analyzed three layers
of South Pacific sediment, each over 2
million years thick in geologic time. The
new measurements, acquired at a site some
3000 km away, are much more robust: 28 layers
(rather than 3), from deeper depths (4830 m
rather than 1300 m), with a better dating
method (beryllium-10 dating) and a more
accurate estimate of the layers' age (in
some cases to within a few 100,000 years).
On the basis of their measurement, the
researchers deduce that the samples
represent the remains of a star that
exploded 2.8 million years ago (with
an uncertainty of 0.3 million years)
at a distance from Earth of some tens
of parsecs."

    It's important to point out that these
atoms had to be physically transported to
Earth as particles or grains, probably adhered
to larger particles or grains, from the site
of the supernova explosion:
    "The German researchers say that after
the stellar explosion, gaseous iron-60
condensed on dust particles, probably
from inside the star. Hitching a ride
on these particles, the iron-60 had enough
velocity to pierce the solar wind and
reach Earth. From the amount of iron-60
in the samples, the supernova must have
been within about 90 light-years, they

   It's worth pointing out for those of you
that don't follow this sport, that this supernova
explosion is MUCH CLOSER and MUCH
MORE RECENT than what astronomers
thought was likely or even possible, but the
evidence is apparently very solid.

    Then, later I found more work by Knie and
Hillebrandt that changed the estimates:

    The collapse of a star that masses many times
the mass of our Sun into a Type II supernova
takes place in less than a second! So the event
that creates the iron nuclei is effectively

    The nuclei all have the same mass; they
all experience the same energy accelerating
them. So velocities are initially very uniform,
and the expanding shell of particles is very
thin and precise. Even after several light
years of travel the shells remain pretty well

    The density of iron particles encountered
depends entirely on the distance to the supernova.
Initially Knie and Hillebrandt guessimated the
supernova that produced "their" 60-Fe at 90 to
125 light years away. Then, refining the results,
they came up with about 75-90 light years away.
The more recent berylium-10 results suggest the
explosion was closer. Now, they are more cautious:
25 to 75 light years away.

    These are the most energetic events in the
Universe. In 1-2 minutes, the SN releases more
energy than our Sun will produce in its entire
10,000,000,000 year lifetime.
    When I say you don't want to be in the
neighborhood, that's like the ultimate under-
statement of all time.
    It happens to all stars with a mass greater
than about three times the Sun's mass; that's
a lot of stars. We can see lots of stars that are
close to the end. Betelgeuse in Orion (easy to
find) is one.
    It could go in 10,000 years. It could go
tomorrow. And it's 430 +/- 100 light years away,
just about right for a danger free front row seat.
(And it could have gone supernova hundreds of
years ago and we could see it tomorrow.)

    And lastly:

    Here's the big quote from:

    "Over the last five to 10 million years, the Solar System
has been moving through the lower density region of
interstellar gas of the Local Bubble. As a result, Earth and
its lifeforms have avoided dangerous flows of cosmic radiation
and gas. Astronomers, however, have discovered a denser cloud
of interstellar gas about 25 ly (7.7 pc) in diameter called
the "Local Fluff" (or "Local Interstellar Cloud") that is
moving towards the Solar System. Stretched out towards
Constellation Cygnus, the stellar winds of young stars in a
star-forming region of the Scorpius-Centaurus Association near
the Aquila Rift (a high-density molecular cloud) have been
blowing the Local Fluff so that its denser parts may reach
Sol's heliosphere in around 50,000 years (Straizys et al,

    "Some wisps of the Local Fluff's denser gas may already
have blown into the Solar System earlier (possibly 33,000 and
60,000 years ago) (Priscilla Chapman Frisch, 1997).
Astronomers hypothesize that such gas clouds can suppress the
Solar Wind so that interstellar gas and dust enters the Solar
System in quantities great enough to affect the Sun and life
on Earth. At the moment, a powerful stellar wind from the
young OB stellar associations of the Local Bubble's expanding
neighbor, the Loop I Bubble, is pushing the Local Fluff aside
(at the rate of 12 miles, or 20 km, per second). That
expanding bubble, however, is also pushing other clouds of gas
towards the Solar System..." [end of quote]

    An abstract of the Frisch study cited in
the above quote can be found at:
    The complete paper in PDF format can be
found at:

    You may notice that one of the Frisch dates is the
same as the earlier date found by Firestone. Don't
believe in too many coincidences, myself.

Sterling K. Webb
----- Original Message -----
From: "Darren Garrison" <cynapse at charter.net>
To: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
Cc: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
Sent: Thursday, December 13, 2007 8:50 PM
Subject: Re: [meteorite-list] Mammoths Found Peppered with

On Thu, 13 Dec 2007 19:30:26 -0600, you wrote:

>And, Firestone has a popular-market book out now (of course):

Hm. Recommended by the people that bought his book:


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Received on Fri 14 Dec 2007 12:14:30 AM PST

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