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(meteorobs) meteoriod parent bodies of the asteroidal variety (was Geminids parent body)
Lew Gramer wrote:
>Antoine Antier wrote:
> >trajectories and whose maxima had been calculated by
both searchers Jack
> >Drummond and Ian Halliday may occur on February,22,
August, 14 ( beta
> >triangulids? I'm not sure of the spelling and alpha
ursamajorids? ) ,
> >september, 29 and december 22 ( Ursids?).
>
>
> Antoine, your post was very intriguing to me! I believe
the 22 Feb shower you
> mention is known as the "Delta Leonids" by IMO, peaking
on 24 Feb: I was aware
> that this shower was thought to be associated with
asteroid 4450 Pan. And of
> course, the relationship between the Geminids and
Phaethon is well known.
>
> But ALL the other asteroidal shower associations you
mention are news to me!
> For example, I thought the Ursids (whose peak is coming
up soon, on 22 Dec)
> were thought to be associated with Comet Tuttle! See,
e.g., Gary Kronk's
> "Meteor Observing Calendar" entry for this shower, on the
Web:
>
> http://comets.amsmeteors.org/meteors/showers/ursids.html
>
> I'd be interested to hear any references you've seen to
non-cometary parent
> bodies for any showers besides the Delta Leonids and
Geminids, Pierre!
>
> Thanks, and clear skies,
> Lew Gramer
Hi Lew
Take yourself to adsabs.harvarddot edu and select the ABSTRACTS button, then
the astronomy and astrophysics link, and then in the author dialogue box,
enter Ichiro Hasegawa. You'll be looking for a paper of potential meteor
shower - asteroid associations written by said, and others, as published in
the Publications of the Astronomical Society of Japan [PASJ]. There might
be a couple, you'll only want the earliest I think.
Now, Jack Drummond has done a lot of work on and off re trying to associate
NEO asteroids into families via orbital similiarity through his own
"Drummond D'" statistic.
As part of this he did some double checking of some of these groups against
Halliday [et al]'s earlier work, where Halliday had tried to find evidence
for streams of meteorite and/or fireball groupings from the MORP dataset.
Hallidays papers are also available via the ADS, sorry I don't remember any
references, but they were invariably in M&PS {Meteoritics and Planetary
Sciences?}
Drummond found some potential connection between some potential near earth
orbit asteroidal families and some of Halliday's potential fireball
groupings... ...potentially... He also more or less confirmed Halliday's
work on the fireball groupings, but this is no great surprise, cos Halliday
et al used Drummond's methods to derive them! Unfortunately most of
Drummond's work ends up in Icarus, whose publishers teasingly keep saying
they'll make their archive stuff available to the ADS, but usually cop out.
Now, and this is stretching memory a bit, I think one of Halliday's
fireball groupings had a cluster of dates around February, and this may
just be where this delta Leonid connection comes in.
Mind you, there's a MORP database fireball with a quite similar orbit to
the Tagish Lake meteorite, but it don't necessarily mean ought.
As for associations of showers with things like 4450 Pan etc, what has got
to be remembered is that most of these associations are based on orbital
similarity, which is usually a combination of statistics re eccentricity,
inclination, semimajor axis, etc. When a shower has small inclination, low
eccentricity, orbital size similar to earth's, etc, then if there are a
bunch of other objects like this, they're gonna appear of similar orbit,
whether they are associated or not. I dunno, lame example: all these NEOs
that are supposed to hit earth eventually, nobody expects them to be old
bits of earth floating around in similar orbits. They're supposed to have
either been injected into the inner solar system from asteroid belt
resonance points due to Jupiter, or in some cases expected to be defunct
comets, though I think that is going a bit out of fashion again [even for
3200 Phaethon]. Or another way: if you've a bunch of objects that have
ended up in near circular orbits of a similar size and low inclination, how
do you tell which are truly genetically related, and which have just ended
up that way.
My fave rave re possible asteroidal connections with meteor showers is 2201
Oljato, which is presumed to have some connection with the Taurid Complex
[which in itself is dependant on you believing in a disrupted massive
progenitor leading to the Taurid Complex, 2P/Encke, some other comets, and
2201 Oljato itself, or whether you take the non-Clube/Asher/etc view that
the Taurid Complex is just a consequence of so much geometry].
One enigmatic piece in the 2201 Oljato puzzle, and it potentially being a
dead comet [and there's bits of circumstantial evidence everywhere for it
being a defunct comet], is that Pioneer Venus Orbiter data showed
ionospheric disturbance [or was it a lack thereof?] at Venus during a time
when that asteroid was directly "down orbit", which at a pinch could have
been due to particulate matter trailing behind the minor planet. Venus has
no magnetosphere to speak of and any "ionosphere" it has is due to direct
interaction between its outer atmosphere and the solar wind. Can't
remember exactly, but I think there was a period of reduced ionospheric
activity when the planet was "downwind" of the planetoid, though what the
mechanism details are eludes me. Someone out there may know???
In summation, there's quite a bit on this sort of thing, but it is very
well hidden, and even the best of it is circumstantial plus!
Many articles available via the ADS can be downloaded as full PDF files...
...actually, it's a bit addictive and self-feeding when you first discover it!
Cheers
John
JG, UK
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