Hi, Jason, Chris, Eric, List,
Now, I'm going to turn around and play Devil's Advocate
and ridicule my own ridicule. Of course the iron Mazapil
came from the Andromedid stream!
Here's a good paper on the Andromedids and their
parent body, Comet 3D/Biela:
http://authors.library.caltech.edu/12800/1/JENaj07b.pdf
From it, we learn that Comet 3D/Biela is a disintegrating
comet that broke into two pieces at aphelion in 1842/43,
but was trailing fragments both before and after that event.
It is the source of the Andromedids, one of six comets
associated with an annual meteor shower.
The previous paper I cited, by Martin Beech, calculated the
original size and mass of Mazapil, assuming it was in the
Andromedid orbit and moving with the dust swarm, that
is, had the same radiant and velocity as an Andromedid.
It would have been a one-meter plus iron body of about
100 tons mass.
The two pieces of 3D/Biela (called imaginatively enough,
"A" and "B") were observed the last time in 1852. A big
search for A and B at the 1865/66 return of Biela failed
to discover them. In the nineteenth century, comets were
considered to be rubble piles anyway and even now, we
think of them as weak and unconsolidated, so no one
is surprised it vanished.
The Andromedids were always a weak shower (a few
hundred per hour) but after Biela's breakup, they started
to put on big shows. In 1885, 15,000 meteors per hour!
Obviously, there was a lot more material in the stream
after the 1842 breakup and the Earth cut through
a denser portion of that stream.
Because we think of comets as inherently weak, we
assign the breakup no other cause than that the comet
was merely falling apart, like an old house collapsing,
but what if it was hit by a 100-ton iron meteoroid?
Biela has plenty of mass (10,000,000 tons) but a 100-ton
fast impactor could do a lot of damage to a weak object,
even one a million times heavier, if it hit it just right.
Maybe fracture it into two pieces? The 100-ton chunk
of iron would be completely undamaged by hitting a
weak object, no matter how massive. It would dig into it,
might even bore right through it, or suffer multiple
collisions with the bigger cometary fragments of its
own impact.
A series of battering, uneven impacts with a disintegrating
comet could steal away most of the kinetic energy of the
iron "wrecking ball." In fact, if the impact brought it to a
relatively low energy of motion, the impactor would lose
all of its "vector." It would be what's called an "inelastic"
collision.
The mostly undamaged iron object would simply fall in and
move on the same vector as the big mass it had hit, thus
sharing its orbit.
One basic rule of physics is that if you can do it with billiard
balls, it can probably happen in the real world! If you drive a
billiard ball at high speed into the belly of (very) giant plush
teddy bear, it will not bounce away with much energy. It will
nearly stop.
And if the impactor, whatever its previous orbit was, fell into
the Biela orbit, it could easily have been unfortunate enough
to encounter the Earth in its path, as did the 100,000+ other
fragments of Biela in 1885.
If you have an iron meteorite that fell as part of an annual
meteor shower, you pick it up and say, "What's YOUR story,
little rock?"
Improbable? Unlikely? A one-in-a-million chance? In a solar
system 4.5 billion years old, a "one-in-a-million" chance means
it's already happened 4500 times.
Sterling K. Webb
----------------------------------------------------------------------------------
Footnote from paper above:
If the bigger lost fragment A survives, it may be "now hiding
as a dormant comet. If so, K. Kinoshita calculated a particularly
good encounter in 2010, when the dormant comet is expected
to pass Earth at only 0.13 AU on November 3.25, following a
close encounter with Jupiter (0.79AU) on 2009 March 13.5."
Maybe an NEA hunt or WISE will find it.
-----------------------------------------------------------------------------------
----- Original Message -----
From: "Jason Utas" <[email protected]>
To: "Sterling K. Webb" <[email protected]>; "Meteorite-list"
<[email protected]>
Sent: Thursday, August 12, 2010 1:20 AM
Subject: Re: [meteorite-list] Meteor shower meteorite dropping events
Haha, but Sterling -- I'd like to refer you to one of the posts (one
of yours!) I linked to in my reply:
http://www.mail-archive.com/[email protected]/msg84604.html
The Wisconsin fall was another coincidence -- and it's not the only
one. If you go through the fall calendars, more than a few meteorites
have fallen on dates that coincide with known meteor showers. This is
especially true if you take into account the fact that "showers" often
produce meteors for weeks leading up to, and away from their peaks.
Mazapil was deemed particularly interesting because it fell during a
very strong outburst of activity from the shower with which it is
associated.
Granted, I'm in no way advocating the cometary origin of any
meteorites. It's simply the result of the frequency of meteor showers
and the frequency with which unrelated meteoric material reaches the
earth...but it has happened more than once.
Regards,
Jason
On Wed, Aug 11, 2010 at 11:01 PM, Sterling K. Webb
<[email protected]> wrote:
Chris, Eric, List,
Mazapil is a very old argument, indeed.
Take a look at:
http://articles.adsabs.harvard.edu/full/2002M%26PS...37..649B
or the same at the author's website:
http://hyperion.cc.uregina.ca/~astro/Mazapil.pdf
and this one:
http://www.lpi.usra.edu/meetings/lpsc1987/pdf/1377.pdf
Personally, the idea that comets drop iron meteorites
is silly. The fact that this is the one and only example, out
of thousands of falls, of the coinciding of a meteorite
fall with a meteor shower suggests to me that when you
flip coins often enough, a coin will land on its edge.
Sterling K. Webb
---------------------------------------------------------------------------
----- Original Message ----- From: "Meteorites USA"
<[email protected]>
To: <[email protected]>
Sent: Wednesday, August 11, 2010 11:34 PM
Subject: Re: [meteorite-list] Meteor shower meteorite dropping events
Thanks for posting this Chris... This sounds like a good topic for
an
article for my magazine. If you're interested in it, and/or would
like to
write for the mag on this topic let me know. Anyone have a working
theory
based on evidence of this associative phenomena? I've heard many
people
suggest that meteor showers don't drop meteorites. Then I've heard
people
associate meteorite falls that happen during meteor showers with
said
shower. And I've also heard that people believe that there is ZERO
connection and it's purely coincidence.
So which is it? yay or nay, or maybe? or no one really knows...?
Eric
On 8/11/2010 8:59 PM, Chris Spratt wrote:
I know of one meteor shower (November Andromedids) where an iron
meteorite fell in Mazapil, Mexico during the shower.
Are there any similar events?
Chris Spratt
Victoria, BC
(Via my iPhone)
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