[meteorite-list] Cool Quadrantids and their Grandparent Bodies

[mexicodoug]

Hello Listees,

http://quadrantid.seti.org/

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 
period.

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 
believable.

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 
understood:
Peter Jenniskens
Emmanuel Jehin
Ichiro Hasegawa
Vladimír Porubcan
Leonard Kornos
Hans Betlem
Marc de Lignie
Zidian Wu
Iwan Williams,
Galina Ryabova
A. P. Baturin
Alexandr Chernitsov
Paul Wiegert
Peter Brown

http://bp2.blogger.com/_iOfdiJGzpkc/Ri4fVcjd5mI/AAAAAAAAAD8/YDAZib6sH8M/s400/dinosaur.jpg

Best wishes and Great Health,
Doug

----- Original Message ----- 
> 2008 QUADRANTIDS
>
> 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