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(meteorobs) Excerpts from "CCNet 50/2001 - 30 March 2001"
------- Forwarded Message
From: Peiser Benny <B.J.Peiser@livjm.acdot uk>
To: cambridge-conference <cambridge-conference@livjm.acdot uk>
Subject: CCNet, 30 March 2001
Date: Fri, 30 Mar 2001 10:38:57 +0100
CCNet 50/2001 - 30 March 2001
-----------------------------
[...]
(2) FIREBALL SEEN OVER NEW HAMPSHIRE
The Register Citizen, 29 March 2001=20
[...]
(7) SPACE MATERIAL MYSTERY
Colin Keay <phcslk@cc.newcastledot edu.au>
[...]
(10) A NEW ASTROPHYSICAL SETTING FOR CHONDRULE FORMATION
Krot AN, Meibom A, Russell SS, Alexander CMO, Jeffries TE, Keil K
(11) THE ORIGINS OF CHONDRULES
Shu FH, Shang H, Gounelle M, Glassgold AE, Lee T
[...]
======================================================================
(2) FIREBALL SEEN OVER NEW HAMPSHIRE
=20
>From The Register Citizen, 29 March 2001=20
http://www.zwire.com/site/news.cfm?newsid=3D1599214&BRD=3D1652&PAG=3D461=
&dept_id=3D1
2530&rfi=3D6
=20
Glenn Carlson and his wife Sondra were traveling home from New =
Hampshire
last weekend when they saw something bright streak across the sky. In =
the
heavens above Route 8 southbound, the South Kent couple saw what they
identified as a shooting star.
The pair admired the glow then noticed it's light flicker, extinguish
momentarily, and bound toward Earth eventually landing in a location =
between
TJ Maxx, O&G Industries, Route 8, and Charlotte Hungerford Hospital.
"It didn't like explode or anything," Glenn said Wednesday. "As it got
closer (into the Carlsons' view) it kind of flared up and it kind of =
blacked
out."
Glenn said he was certain the object wasn't a bottle rocket or any
mysterious visitor from outer space, merely a meteor speeding wayward
through the atmosphere.
"It was pretty neat," Glenn said.
Susan French, vice president of the board of trustees for the Dudley
Observatory in Schenectady, N.Y. and a star party coordinator for the =
Albany
Amateur Astronomers Club, said the Carlsons indeed might have seen a =
meteor.
The only thing, she said, is a meteorite, once it hovers about 12 miles
above the Earth, extinguishes itself entirely and could land anywhere =
at
anytime. So pinpointing an exact location from a streak in the sky =
would be
nearly impossible.
Most people identify fallen meteorites if the chunk of space rock hits
something, such as a house or a car, or if a person stumbles upon =
something
strange in a wooded area, French said.
"There always are meteor showers," she continued. "There's a good =
chance he
saw a meteor."
A meteor, or shooting star, rapidly crosses the sky in about 15 =
seconds,
whereas a satellite or an airplane takes much longer, French explained. =
And
this time of year is ripe for meteors, as the March showers are now =
coming
to an end.
The only thing about which French was skeptical was the height the =
Carlsons
said they saw the object. Generally, 60 miles in the air is when people =
see
the burning rocks.
But then again, some could say it might have been something other than =
a
meteor.=20
(c) The Register Citizen 2001
======================================================================
* LETTERS TO THE MODERATOR *
======================================================================
(7) SPACE MATERIAL MYSTERY
>From Colin Keay <phcslk@cc.newcastledot edu.au>
Dear Benny:
Here's a nice little mystery. Late yesterday afternoon (Thursday 2001
March 29) I was contacted by a man acting on behalf of a home-owner on
whose roof an object landed at around midnight AEDT on March 24/25 with
enough force to wake them up. Next morning the family's children picked
up bits of jet-black crumbly material from near the house and went onto
the roof to retrieve more. The house is located about 30km from
Newcastle. At first the owner's family and neighbours thought it all
rather a joke but a few days later a friend of the owner thought it
sensible to get an opinion on its origin. Eventually his inquiries
led to me and I invited him to bring me the sample he held. He did so,
with it wrapped in a paper tissue. I took one look at it and
immediately placed it in a sealable plastic bag, although it is
likely to be rather contaminated through earlier handling.
The sample is very irregular in shape and approx. 38 x 20 x 8 mm
overall weighing 0.87 gm. It is jet-black with a few tiny ~< 1 mm
reflective facets.
It is fairly fragile and crumbles readily. There are suggestions of
striations of about 0.2 - 0.3 mm spacing. A geologist assures me that
it is not of terrestrial origin. I have contacted Dr Andrew Smith of
ANSTO who will be happy to analyse it with his accelarator mass
spectrometer, so I'll take what I can to Sydney on Monday for him
to do an elemental and then isotope analysis.
In the meantime I contacted the the home-owner last evening and
gave instructions for collecting as much residue as possible with
least contamination. Hopefully I'll hear back later today and will
likely travel to the site tomorrow (Saturday March 31).
If it fell from space its entry fireball must have been only of
moderate brightness or else there'd have been reports of it. The
two possibilities are A: cometary origin, or B: space junk. If
cometary it could be what Ceplecha classes as very low density,
but although it looks to be carbonaceous I see no chondrules. If
it is space junk there is an intriguing possibility it is from
the demise of Mir, about 31 hours earlier. At the time of the
fall this part of Australia would have been under the Mir orbital
plane toward the ascending node. We are at lat -32 deg, Mir
inclination I believe was 51 deg. So the mystery is why the
fragment(s) remained in space for a further 20-21 orbits after
Mir's demise.
So that's where I'm at this morning, Friday, March 30. I will
keep you posted. It is an amazing coincidence that only two days
ago I attended a conference at the Police Forensic HQ in Sydney
to discuss the likely origin of a large block of ice that crashed
through the roof and ceiling of a house at Harbord, in Sydney on
March 6. For my money it came from an aircraft, because it was
mainly clear and partly transparent. It will be analysed.
Colin Keay
University of Newcastle, NSW.
***************************************************************************
* Dr Colin Keay ::::::: ~ ~ To achieve anything really *
* Physics Dept ~ ::::: ~ worthwhile in research it is *
* Newcastle Univ ~ :::\ | / ~ necessary to go against the *
* NSW, AUSTRALIA 2308 ~ ~ - o - opinions of one's fellows. *
* phcslk@cc.Newcastledot edu.au / | \ ~ "Where the Wind Blows" *
* www2.hunterlinkdot net.au/~ddcsk ~ ~ ~ - Fred Hoyle *
***************************************************************************
======================================================================
* ABSTACTS *
======================================================================
(10) A NEW ASTROPHYSICAL SETTING FOR CHONDRULE FORMATION
Krot AN, Meibom A, Russell SS, Alexander CMO, Jeffries TE, Keil K: A =
new
astrophysical setting for chondrule formation. SCIENCE 291: (5509)
1776-1779 MAR 2 2001
Chondrules in the metal-rich meteorites Hammadah al Hamra 237 and QUE =
94411
have recorded highly energetic thermal events that resulted in complete
vaporization of a dusty region of the solar nebula (dust/gas ratio of =
about
10 to 50 times solar). These chondrules formed under oxidizing =
conditions
before condensation of iron-nickel metal, at temperatures greater than =
or
equal to 1500 K, and were isolated from the cooling gas before =
condensation
of moderately volatile elements such as manganese, sodium, potassium. =
and
sulfur. This astrophysical environment is fundamentally different from
conventional models for chondrule formation by localized, brief, =
repetitive
heating events that resulted in incomplete melting of solid precursors
initially residing at ambient temperatures below approximately 650 K.
Addresses:
Krot AN, Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii =
Inst
Geophys & Planetol, Honolulu, HI 96822 USA.
Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys =
&
Planetol, Honolulu, HI 96822 USA.
Stanford Univ, Stanford, CA 94305 USA.
Nat Hist Museum, Dept Mineral, London SW7 5BD, England.
Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 =
USA.
Copyright =A9 2001 Institute for Scientific Information
======================================================================
(11) THE ORIGINS OF CHONDRULES
Shu FH, Shang H, Gounelle M, Glassgold AE, Lee T: The origin of =
chondrules
and refractory inclusions in chondritic meteorites ASTROPHYSICAL =
JOURNAL
548: (2) 1029-1050, Part 1 FEB 20 2001
Examples of calcium-aluminum-rich inclusions (CAIs) surrounded by thick
chondrule mantles have been found in chondritic meteorites and cast =
doubt on
the conventional belief that CAIs and chondrules possessed different
spacetime origins in the primitive solar nebula. We study specific =
processes
by which such objects, and the more common ordinary CAIs and =
chondrules,
might have formed by flare heating of primitive rocks interior to the =
inner
edge of a gaseous accretion disk that has been truncated by magnetized
funnel flow onto the central proto-Sun. Motivated by the appearance of =
the
chains of Herbig-Haro knots that define collimated optical jets from =
many
young stellar objects (YSOs), we adopt the model of a fluctuating =
X-wind,
where the inner edge of the solar nebula undergoes periodic radial
excursions on a timescale of similar to 30 yr, perhaps in response to
protosolar magnetic cycles. Flares induced by the stressing of magnetic
fields threading both the star and the inner edge of the fluctuating =
disk
melt or partially melt solids in the transition zone between the base =
of the
funnel flow and the reconnection ring, and in the reconnection ring =
itself.
The rock melts stick when they collide at low velocities. Surface =
tension
pulls the melt aggregate into a quasi-spherical core/mantle structure, =
where
the core consists mainly of refractories and the mantle mainly of =
moderate
volatiles. Orbital drift of rocks past the inner edge of the disk or =
infall
of large objects from the funnel flow replaces the steady loss of =
material
by the plasma drag of the coronal gas that corotates with the stellar
magnetosphere. In quasi-steady state, agglomeration of molten or
heat-softened rocks leads to a differential size-distribution in radius =
R
proportional to R(-3)e(-Lt)/(tLR), where t(L) similar to yr is the =
drift
time of an object of fiducial radius L =3D 1 cm and t is the time since =
the
last inward excursion of the base of the funnel flow and X-wind. Thus,
during the similar to 30 yr interval between successive flushing of the
reconnection ring, flash-heated and irradiated rocks have a chance to =
grow
to millimeter and centimeter sizes. The evaporation of the moderately
volatile mantles above large refractory cores, or the dissolving of =
small
refractory cores inside thick ferromagnesian mantles before launch, =
plus
extended heating in the X-wind produce the CAIs or chondrules that end =
up at
planetary distances in the parent bodies of chondritic meteorites.
Addresses:
Shu FH, Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, =
CA
94720 USA.
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA.
Acad Sinica, Inst Astron & Astrophys, Taipei 115, Taiwan.
Ctr Spectrometrie Nucl & Spectrometrie Masse, F-91405 Orsay, France.
NYU, Dept Phys, New York, NY 10003 USA.
Acad Sinica, Inst Earth Sci, Taipei 115, Taiwan.
Copyright =A9 2001 Institute for Scientific Information
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