[meteorite-list] Fireballs & Known Meteor Showers

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Fri, 16 Apr 2010 16:31:30 -0700 (MST)
Message-ID: <dcb32aefda0a08f67cda4c76733027b8.squirrel_at_webmail.lpl.arizona.edu>

Hi Phil, Chris, Sterling, and Carl (et al.):

One of the first articles (newscasts??) mentioned the Gamma shower which
made no sense, but reminded me of a talk I gave a few years ago about the
sources of meteor showers. I found the following on Wikipedia:

Gamma Virginids
The North and South Gamma Virginids are a slow-moving minor meteor shower
stream, although the May Gamma Virginids and Daytime Gamma Virginids are
faster-moving. The source of the North and South Gamma Virginid streams
are thought to be 2002 FC and 2003 BD44, respectively. It usually spans
from April 5 to April 21, peaking on April 14 and April 15, with less than
five meteors per hour. It was first discovered in 1895.

I know nothing about the spectral classes of either asteroid, or even if
they have been observed in the last 7-8 years (need to check this out).
But, if we are talking about possible asteroidal debris from an impact
rather than an extinct comet, who knows.

Both have well-determined orbits from what I can tell. 143404 (2003 BD44)
was last observed in November and there have been nearly 300 observations
of it since it was first discovered in 1981 (probably a prediscovery
detection). It is an Apollo asteroid that is considered to be a
"Potentially Hazardous Asteroid" and has a highly elliptical orbit
(e=0.60). 2002 FC is also listed as a Potentially Hazardous Asteroid, has
been observed over 200 times since its discovery and seems to have been a
radar target! It also has a highly elliptical orbit (e=0.66). They do not
seem to be at all related, based on their orbital elements (there was
hope): the mean distance of 2002 FC is toward the outer part of the
asteroid belt while 2003 BD44 has a mean distance at the inner part of the
belt.

Are either of these extinct comets? Who knows? I do not know much more
about them (size, albedo, etc.).

Larry



> Aren't the current meteor showers the Alpha Virginids, not the Lyrids?
> Though I highly doubt their parent body is an H chondrite.
>
> Phil Whitmer
>
> ------------------------
>
> Carl, List,
>
>
>> how we know with certainty that the WI fall is not
>
>> related to the known shower of the same time period?
>
>
> The Wisconsin Stone is a probable H5. The source
> of the Lyrid meteor shower is Comet Thatcher (C/1861 G1).
> I doubt that Comet Thatcher is an H5 condrite body.
> It sure don't act like one...
>
> "Certainty" is a tricky term. I've never been to Comet
> Thatcher and drilled into it, so I can't swear you out
> an affidavit that it isn't an H5 body, but the claim that
> it is would be extraordinary.
>
> And extraordinary claims require extraordinary proof,
> as another guy named Carl used to say...
>
>
> Sterling K. Webb
>
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Received on Fri 16 Apr 2010 07:31:30 PM PDT