[meteorite-list] Pairing ?-Type Asteroids to OC's (fromArkansas)

From: Frank Cressy <fcressy_at_meteoritecentral.com>
Date: Sun, 13 Jul 2008 08:27:05 -0700 (PDT)
Message-ID: <463853.73294.qm_at_web80205.mail.mud.yahoo.com>

Hello Sterling and all,

Just got around to catching up on the list mail and
read these threads about pairing of young asteroid
families. I wonder why the authors used the
Fayetteville meteorite to compare to the spectral data
of their "young" asteroid families since Fayetteville
is more than just an ordinary chondrite. In fact it
is classified as a regolith breccia or a meteorite
that is composed of the same old weathered "space
dirt" that has they are trying to avoid by looking at
the spectral data at "young" asteroid families. Maybe
these families aren't as fresh and "young" as the
authors thought.
Curious ;-)

Cheers,

Frank
--- "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
wrote:

> Doug, List,
>
> Here is the another presentation article on the
> age and number of asteroid families by David
> Nesvorn? and William Bottke of SwRI:
> http://www.on.br/acm2005/presentation/R9.2.pdf
> Very colorful presentation, despite the fact that
> the document code contains the meta-title:
> "Design of a Locomotive Engine for Dalian
> Locomotive & Rolling Stock Works."
>
> Now, I'm trying to figure out why Salvador Dali
> would want SwRI to design a locomotive engine
> for him, and just what a Dalian Locomotive would
> look like...
>
>
> Sterling K. Webb
>
----------------------------------------------------------------
> ----- Original Message -----
> From: <mexicodoug at aim.com>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Thursday, July 10, 2008 5:25 PM
> Subject: Re: [meteorite-list] Pairing ?-Type
> Asteroids to OC's
> (fromArkansas)
>
>
> Hi Listees:
>
> There may be a little more going on here than this
> quickly published
> note with such a glorious title "Discovery of the
> Source of the Most
> Common Meteorites". It seemed a little odd and
> quickly put together.
> Probably is some good work, but ... I see next week
> at the Asteroids,
> Comets and Meteors Meeting,
>
> http://acm2008.jhuapl.edu/
>
> is the following paper:
>
> PHYSICAL CHARACTERIZATION OF VERY YOUNG ASTEROID
> FAMILIES. P.
> Vernazza1, R. P.
> Binzel2, A. Rossi3, M. Birlan4, S. Fornasier5, M.
> Fulchignoni5, S.
> Renner6.
>
>
http://www.lpi.usra.edu/meetings/acm2008/pdf/8044.pdf
>
> In which the Datura and other families have their
> spectra taken and
> studies.
>
> Hmmm ... sounds like someone may be looking for some
> extra press a few
> days before the ACM meeting. Vernazza, Binzel, et
> al group has done
> the spectra up to 2.5 microns and looks like a much
> more comprehensive
> work.
>
> Also in my original comments, I mentioned S-Type
> Asteroids. I take
> that back until it can be confirmed - from the press
> release they may
> be Q-Type a stony sub-group (with metal), and
> uncommon subcategory.
> Time will shortly expose more of this if it hasn't
> already.
>
> Best wishes,
> Doug
>
>
>
>
>
> I wrote:
>
>
http://www.sciencedaily.com/releases/2008/07/080710103903.htm
>
> The press release was confusing to me at first,
> highlighting the
> Fayetteville H4 (fall, Arkansas) meteorite. Perhaps
> they did because of
> being fresh and closer to the surface (?) in the
> parent body model. Not
> sure why the 1270 Datura family, etc., would be
> expected to be from the
> relatively rarer surface of the original parent body
> vs more common
> heat altered interior).
>
> In any caseit seems they are NOT claiming that
> (1270) Datura is the
> parent body to any of our meteorites (how could it
> be - don't virtually
> all ordinary chondrites have CRE's of floating
> around as meteoroids
> well over 1 million years?)
>
> However, it seems they are pointint out that because
> it is an S-type
> asteroid that has apparently suffered a collision
> only 450,000 years
> ago(which was shown by other researcher a studying
> the probabilities of
> members' orbits couple of years ago), it gives an
> opportunity to study
> fresher material of this most common high silicate
> asteroid type by
> telescopic spectroscopy, and they had an opportunity
> to take the
> spectra. I guess they only look at the 0.5 and 1 um
> peak because it is
> more sensitive to space weathering (?), but this
> isn't too clear
> either. (the authors didn't extend it to the typical
> 2.5 microns where
> some good stuff is visible - at least not in figure
> in the press
> release).
>
> In any case, their proposed contribution seems that
> they measured
> spectra of theyoung Datura family and compared it to
> ordinary chondrite
> spectra and got a better match than ever before
> helping to solve the
> conjecture that the common asteroid class (second
> only to supposed
> carbonaceous chondrites typed asteroids) should be
> paired to common
> meteorites. Hopefully they make a case for a trend
> in asteroid
> reflectance spectra vs. age, vs. a one hit wonder,
> but there still seem
> to be more complexities to be ironed out regarding
> what meteorite is
> appropriate to compare to what asteroid in the clan,
> IMO. Maybe
> Fayetteville was just selected because it is what
> they had access to...
> Article sounds like it will be a good one. Comments?
>
> Best wishes, Doug
>
> PS Interestingly, Wikipedia (at this moment - no
> doubt it will be fixed
> by someone reading this) says the Datura cluster
> formed 450 MILLION
> years ago and a probable source of zodiacal dust....
> Maybe Wikipedia
> can't be trusted yet again, once the dust has
> settled :)
>
>
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
>
http://six.pairlist.net/mailman/listinfo/meteorite-list
>
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
>
http://six.pairlist.net/mailman/listinfo/meteorite-list
>
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
>
http://six.pairlist.net/mailman/listinfo/meteorite-list
>
Received on Sun 13 Jul 2008 11:27:05 AM PDT