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RE: R: (meteorobs) WM1 shower?
We have with Peter Jenniskens a small article in the WGN 2001 April issue,
on the possibility of this comet producing an outburst. The calculated one
revolution trail doesn't come more close than about 0.01 au from the Earth's
orbit (at the ascending node, where the Earth is May 19). This conclusion
for the trail is at least for the calculated 25 years to come, but very
probably true for centuries. The comet itself passes at about the minimum
separation (from Eart's orbit) of the twisted trail.
If the trail would intersect the Earth orbit, the (very long extending)
trail would be very scarce, because of the long period of the comet. Hardly
anything observable would be predicted. It would however deserve to try to
observe, if an encouter were predicted, in some of the future years.
Some level outburts can be produced from one revolution trails of comets
with periods at least to a few thousand years, as Marco told and gave the
reference. There are a few more papers from Peter Jenniskens (et al) on the
long period outbursts.
Actually we have had with Peter a project going, on the direct calculation
of one revolution long period trails. This has been only slowly advancing
now for about two years, and interrupted by many other things like the
Leonids. Now the draft version is practically ready for planned submission
to the WGN. Mainly some checks on data and English need be made. Because of
large amount of Leonids data probably published in the near future in the
WGN (and some other things now taking my time), it will probably not be
submitted very soon.
On the alpha Monocerotids orbital period, I think it likely to be at least a
few hundred years. (..but probably not more than one or maximum a few
thousand years). This (lower limit) is because the one revolution trail
extends quite strong at least from 1925 to 1995.
The one revolution Leonids trail seems (in our model) to weaken strongly at
about delta_a=0.3 au, or around one and a half years, although observable
some years further..
Assuming about equal q:s, the length in time can be approximated (with
similar ejection model) to be proportional to the semimajor axis powered to
2.5 . Because the semimajor axis with the Leonids is about 10, the (one
revolution) length with a=100 (period 1000 years) would be about 300 times
as long (or around 500 years, a big fraction of the whole orbit, probably
then already too weak to produce a clear outburs).
Esko
>>>
----- Original message -----
From: Cooke, Bill [mailto:Bill.Cooke@msfc.nasadot gov]
Sent: 10. joulukuuta 2001 23:16
To: 'meteorobs@atmob.org'
Subject RE: R: (meteorobs) WM1 shower?
With regard to the Aurigids and Comet Kiess, I agree, though the maximum
rate for this shower has never been observed to exceed a ZHR of 40.
There is no doubt that Kiess is a long period comet, with a period of
~6300 years.
I stand corrected - thank you for bringing this to my attention. I
amend my statement to state that only periodic comets can produce
meteor showers. You learn something every day in this field :)
However, with regard to the alpha Monocerotids, your paper states
that there is a 98% probability that the period of the parent comet
exceeds 140 years. Since a long period comet's period must exceed
or equal 200 years, your results do not rule out a short period
comet as a progenitor for this shower; indeed the uncertainties
in your 1/a measurements exceed the determinations for all but
one of your points. In short, all you can really say is that the
1/a for the shower meteors is less than your experimental uncertainty,
which appears to be on the order of 0.05 AU^-1.
Regards,
Bill Cooke
CSC/ED44
Marshall Space Flight Center, AL 35812
Phone: (256) 544-9136
FAX: (256) 544-0242
Email: bill.cooke@msfc.nasadot gov
> -----Original Message-----
> From: Marco Langbroek [mailto:marco.langbroek@wanadoodot nl]
> Sent: Monday, December 10, 2001 1:45 PM
> To: meteorobs@atmob.org
> Subject: Re: R: (meteorobs) WM1 shower?
>
>
>
> ----- Original Message -----
> From: "Cooke, Bill" <Bill.Cooke@msfc.nasadot gov>
> Sent: Monday, December 10, 2001 4:33 PM
>
> > Comet WM1 is a long period comet, and meteor showers are
> only produced
> > by short period comets.
>
> I am sorry, but this is incorrect. The Aurigids on September
> 1 (both an
> annual stream and producing outbursts) are due to a long period comet,
> C/Kiess. And the alpha Monocerotids in November with big
> outbursts in 1925,
> 1935, 1985 and 1995 are due to a long period comet, see our
> paper in the
> Astrophysical Journal (Jenniskens P., Betlem H., De Lignie M.
> and Langbroek
> M.: The detection of a dust trail in the orbit of an Earth-threatening
> long-period comet. The Astrophysical Journal 479 (1997), 441-447).
>
> For the rest of course you are right: only an encounter with
> 'old' dust
> would be possible, not with dust from the current perihelion passage.
>
> Marco Langbroek (DMS)
>
>
> ---
> Marco Langbroek private: marco.langbroek@wanadoodot nl
> Leiden University work:
> m.langbroek@arch.leidenunivdot nl
> Faculty of Archaeology
> P.O. Box 9515
> http://home.wanadoodot nl/marco.langbroek/
> NL-2300 RA Leiden
> The Netherlands
> ---
>
>
>
>
> The archive and Web site for our list is at http://www.meteorobs.org
> If you are interested in complete links on the 2001 LEONIDS, see:
> http://www.meteorobs.org/storms.html
> To stop getting email from the 'meteorobs' list, use the Web form at:
> http://www.meteorobs.org/subscribe.html
>
The archive and Web site for our list is at http://www.meteorobs.org
If you are interested in complete links on the 2001 LEONIDS, see:
http://www.meteorobs.org/storms.html
To stop getting email from the 'meteorobs' list, use the Web form at:
http://www.meteorobs.org/subscribe.html
The archive and Web site for our list is at http://www.meteorobs.org
If you are interested in complete links on the 2001 LEONIDS, see:
http://www.meteorobs.org/storms.html
To stop getting email from the 'meteorobs' list, use the Web form at:
http://www.meteorobs.org/subscribe.html