[meteorite-list] Cool Quadrantids and their Grandparent Bodies

From: mexicodoug <mexicodoug_at_meteoritecentral.com>
Date: Thu, 27 Dec 2007 20:39:30 -0600
Message-ID: <023001c848fa$e05ec430$4001a8c0_at_MICASA>

Hello Listees,


An interesting post just showed up in the meteor observing forum.

The subject is an airline mission cramming lots of neat instruments and
scientists like sardines into a jet that could be the subject of a Gary
Larson "Far Side" cartoon is the prettiest meteor shower from the "extinct"
(borrowing a term from another post) constellation with a potentially
dormant parent body.

This is the olde "Wall Quadrant" constellation near Bootes, the hort-lived
but highest meteor rate of the biggies: the QUADRANTID meteor shower, named
after a half protractor formerly used to measure astronomical positions in
the sky.

The cool (brrrr...) thing is: the scientists syncronize in flight so that
they catch the somewhat variably hitting meteor shower's peak at fixed
altitude in the sky anytime during the flight - offsetting the change in
altitude caused by the rotation of earth, and measuring the flux
characteristics of meteors and direction all along with a variety of
methods, which will be determined exactly as before peak and after peak
later upon analysis. Now that is observation in style!

Apparently the objective of the mission is to determine whether the
Quadrantids are from a 520 year old cometary/asteroidal breakup, or if not,
from something else or older, which is a current theoretical disagreement
among scientists regarding the parent body's conversion into a meteor
stream. There is a lot agreement that 2003 EH1 is a parent body, but no
agreement whether it is THE parent body.

EH1 is basically a shuttle between Earth and Jupiter nearly perpendicular to
the Solar System plane. A very loving asteroid or dormant comet, it gets to
withing 0.2 AU from Earth on the Mars' side and 0.2 AU from Jupiter on the
Jupiter side. Nowadays, anyway - it has been shown to have an extremely
changeable orbit, due to the close approaches to Jupiter...

The logic is, that by observing the flux with the radiant (orbit
intersection with Earth), they can determine how spread out the stream has
become, since there is already some good data taken over the last few years
with some really lucky observations in the last pass in 2003. Jupiter has
made a close enough pass to be measurable on the part of the stream passing
us now. Since the stream's orbit is predicted at least partly from the
parent body 2003 EH1 in one leading hypothesis,and that EH1 happens also to
coincide with the maximum flux in the whole Quadrantid stream of 5.5 years

But breakdown of orbits of individual meteoroids in this meteoroid stream
has found several different "filaments" (and this is another reason the
prediction of the exact timing of the peak has been difficult . Two major
filaments coincide nicely with EH1,but, three others don't. The
interpretation of this subject to proof is that each "filament" corresponds
to a possible break-up event of a comet, and that EH1 was one major fragment
and there are others to be evaluated and found. Note, that this is not the
general case for all meteoroid streams, only can we hope to find large,
semi-dormant cometary fragments peacefully cohabitating in meteoroids when
the breakup is fairly recent, given their presumed fragility. In this case
there are recorded observations from Asian astronomers in 1490 of a bright
comet that may fit the description and was not subsequently recorded or
otherwise accounted for: C/1490 Y1. This comet seems to be a candidate for
the creation of the Quadrantids and grandparent of 2003 EH1. Recent
measurements of 2003 EH1 with ESA telescopes have made this even more

This shower is produced by the stream that is just about the sharpest
(shortest lived, defined peak) of all good showers on Earth. The reason it
is sharp is hypothesized as related to its recent creation. But it is still
a theory in progress. If it is recent, they would attribute noticable
influence from Jupiter's gravitation on the meteor stream orbit near its
aphelion by Jupiter, as particles are "stretched" out near there when they
are especially slow and least susceptible to the Sun and most to Jupiter, by
similar effects we are all familiar with in the meteorite world. If this
theory is right and it is so young the model would predict measurements once
an appropriate scenario is selected for the formation - and the theory would
be validated by experiment - a requirement of the scientific method for any
assertation to reach a peer-respectably "hypothesis" status. Then all the
filaments could be rewound mathematically and tell us more about the
original comet break-up event which may have been an the outburst seen
subsequent to, a close approach to ... of course Jupiter...

Some of the scientists's theoretical discovery work behind this include, and
it is a large work in progress as this meteoroid stream becomes better
Peter Jenniskens
Emmanuel Jehin
Ichiro Hasegawa
Vladim?r Porubcan
Leonard Kornos
Hans Betlem
Marc de Lignie
Zidian Wu
Iwan Williams,
Galina Ryabova
A. P. Baturin
Alexandr Chernitsov
Paul Wiegert
Peter Brown


Best wishes and Great Health,

----- Original Message -----
> If all goes to plan, this year's Quadrantids will be the
> focus of an airborne mission described at:
> http://quadrantid.seti.org/
> It would help us if Quadrantid observations could be made
> by ground-based observers in the hours (and days) before
> and after the 9 hour time interval covered by our mission.
> We are particularly interested in ZHR measurements and in
> precise multi-station observations of Quadrantid orbits.
> Good luck and a Happy NewYear!
> Dr. Peter Jenniskens
> SETI Institute
Received on Thu 27 Dec 2007 09:39:30 PM PST

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