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Re: (meteorobs) Re: Encke and Taurids this year?
Gary, Marco and Bruce's consideration of resonance with Jupiter are
definitely correct. As I also mentioned in the post on the other day that
current Taurid meteors are mainly ejected from Encke thousands of years ago.
But I'm supposing another possibility may be effective as well just for this
year, i.e. the component around JFC nuclear. The shape of this idea was due
to our work on asteroid 2001 YB5, which was away from the earth on January
7,
2002, only 2 lunar distances. That asteroid travels on a JFC (Encke-like)
orbit with Tisserand parameter of 2.84. Its eccentricity is up to 0.864,
similar with Geminids' parent, (3200) Phaethon (e=0.890). Our spectroscopic
observations revealed that asteroid belongs to the same spectrum type with
Phaethon, too, i.e. bluish B-type. While, B-types are not so common in the
entire
taxonomy. Especially, we caught its related weak meteor activity at the time
of the close encounter. This may remind us extinct cometary nuclei may fall
into a same or several certain spectrum type(s), B (as indicated by Phaethon
and 2001 YB5) or D (as widely regarded previously).
PS, I think I used to mention the potential event before our monitoring, but
mistaked it with another meteor shower, delta-Cancrids (DCA). In fact, we
finally distinguish 2001 YB5's meteor shower and DCA. They are similar, but
different!
However, the meteor activity of 2001 YB5 was only detected in 2002 because
of the approach. We have attempted to look up any evidence of its existence
in early years from IMO's video observations, but found none. So, one of the
best solutions of the fact is 2001 YB5 only maintains weak spatial dust
component around it and has missed most others through the orbit. For the
case of Encke, an active comet, if it also protect a relatively large scale
structure
around it, we may only have opportunities to catch it in which year the
earth is near to the comet nuclear. Obviously, if the interpretation above
is right, this near-nuclear component should have slightly different orbit
and radiant than annual Taurids. In fact, they have undergone different
mechanical circumstances. The Taurids is evolved by the perturbation of
Jupiter; but the near-nuclear component, if exists, is similar with Encke
(since similar initial true anomaly?) but only have some dispersion in such
a long history.
Of course, a numerical simulation including non-gravitational effects should
be necessary for quantitive description. But i'm sorry maybe i've no time to
do this recently. So, it's just a guesswork now, comparing with the case of
2001 YB5. In any way, it will be always good for us to observe and monitor
it
first #;-)
Best wishes,
Huan
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