[meteorite-list] Fireballs & Known Meteor Showers

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Fri, 16 Apr 2010 05:29:39 -0700 (MST)
Message-ID: <f8ede30ba21fb8fdec6f6cffeb02271c.squirrel_at_webmail.lpl.arizona.edu>

Hi All:

My impression (I too need to do some more research) is that at least
infrared observations of Stardust particles imply that they are similar to
(at least in one this respect) to IDPs (Interplanetary Dust Particles) and
are anhydrous silicates. The implication being that comets (a least the
dust theat comes of from them) are made up of silicates and ices, but that
the comet (surfaces) have never been warm enough for the ice to have
melted and reacted with the silicates in order to form hydrated silicates
(as seen on the surfaces of many asteroids and is the case with CIs).

Jeff, it was way before the Stardust mission that scientists gave up the
idea that CIs had anything to do with comets. It takes water to get CIs
and at least on the surfaces of comets (and in Stardust, IDPs, and
probably from Deep Impact) there is no indication of hydrated cometary
silicates (interiors are another issue).

Tagish Lake (again I need to update and reread papers) is a C2 and is
essentially unaltered, as would be expected for cometary material.

Swindle and Campins did an artlcle on the comet/meteorite connection in
Meteorite magazine in 2006. They conclude that cometary material may just
be too fragile to survive, though a few clasts in meteorites may be of
cometary origin.

Tagish Lake is C2 (and is clearly less altered than CIs (C1) and is a
better candidate for a comet. I must admit I do not know about a possible
CH/CB connection (I need to ask the right people).

Larry

> I believe I heard that the original theory of the CI chondrites having a
> likely comet origin was altered after the Stardust mission. I think they
> found that the closest match was actually the CH/CB chondrite group. I
> would
> need to do a bit more research and see how true that is though. Or maybe
> someone on list has looked at some more recent work on that mission?
>
> Cheers,
>
> Jeff
>
>
> ----- Original Message -----
> From: "Greg Stanley" <stanleygregr at hotmail.com>
> To: <geozay at aol.com>; <meteorite-list at meteoritecentral.com>
> Sent: Friday, April 16, 2010 7:48 AM
> Subject: Re: [meteorite-list] Fireballs & Known Meteor Showers
>
>
>
> List:
>
> Has a meteorite "fall" ever been attributed to a comet? If so, do they
> know
> which one? I remember reading that Tagish Lake may be.
>
> Greg S.
>
> ----------------------------------------
>> From: GeoZay at aol.com
>> Date: Thu, 15 Apr 2010 17:44:27 -0400
>> To: meteorite-list at meteoritecentral.com
>> Subject: Re: [meteorite-list] Fireballs & Known Meteor Showers
>>
>>>>Of course they're not related, as the fireballs are from the asteroid
>> belt
>> and the meteor showers are from the tails of comets.<<
>>
>> Fireballs are produced by both asteroids and comets. So far meteor
>> showers
>> are related to comets.
>> GeoZay
>>
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Received on Fri 16 Apr 2010 08:29:39 AM PDT