PLEASE NOTE:
*
CCNet DIGEST, 26 November 1998
------------------------------
(1) STONEHENGE 'BUILT AS AIR RAID ALERT'
The Daily Telegraph, 26 November 1998
http://www.telegraph.co.uk:80/et?ac=001229738024842&rtmo=rESDbbkX&atmo=99999999&pg=/et/98/11/26/ecnston26.html
(2) DIARY OF A LEONIDS MISSION
BBC
Tomorrow's World <http://www.bbc.co.uk/tw/9899/981125news.shtml>
(3) IS THIS HOW EVOLUTION WORKS? HEAT SHOCK PROTEINS TRIGGER
GENETIC
MUTATION IN RESPONSE TO ENVIRONMENTAL
CATASTROPHES
BBC Network Online
http://news.bbc.co.uk/hi/english/sci/tech/newsid_222000/222096.stm
(4) NEW TUNGUSKA PAPER
Duncan Steel <dis@a011.aone.net.au>
wrote:
(5) ACTIVITY PROFILE OF THE 1998 LEONIDS
Rainer Arlt <rarlt@aip.de>
(6) COMETARY OUTBURSTS AT LARGE HELIOCENTRIC DISTANCES
P. Gronkowski et al., PEDAGOG UNIVERSITY,
POLAND
(7) A DOUBLE NUCLEUS OF COMET EVANS-DRINKWATER
Z. Sekanina, CALTECH, JET PROP LAB
(8) WATER ICE IN COMET HALE-BOPP
E. Lellouch, PARIS OBSERVATORY
====================
(1) STONEHENGE 'BUILT AS AIR RAID ALERT'
From The Daily Telegraph, 26 November 1998
http://www.telegraph.co.uk:80/et?ac=001229738024842&rtmo=rESDbbkX&atmo=99999999&pg=/et/98/11/26/ecnston26.html
By Robert Matthews
THE mystery of Stonehenge may have been solved. A leading British
astronomer has found astonishing evidence that it was an early
warning
system for meteor storms.
It has long been suspected that Stonehenge served some
astronomical
purpose, as many of its stones are aligned with events such as
the
rising of the midsummer sun.
Dr Duncan Steel, an authority on comets, was researching the
cause of
cosmic impacts such as the Tunguska event of 1908, when a meteor
exploded over Siberia with the energy of a hydrogen bomb.
Calculations point to the existence of a giant comet that entered
the
solar system 20,000 years ago and disintegrated, leaving a trail
of
debris through which the Earth occasionally wanders. Dr Steel
found
that the Earth would have been at greatest risk from meteor
impacts
about 5,000 to 5,500 years ago - when work began on Stonehenge.
He also
found that on the day of highest danger, the comet trail would
have
risen above the horizon at Stonehenge in line with the Heel
Stone.
Dr Steel believes that the link between the Heel Stone and
midsummer's
day is a fluke - that the Earth cut across the debris trail
around the
same time. And he suggests that the Long Barrows, usually thought
to be
Iron Age burial chambers, might have been built for a very
different
purpose. "They certainly look like air-raid shelters -
perhaps that's
what they are."
His report is published this week by Archaeopress.
Copyright 1998, The Daily Telegraph
--------------------------------------
BRITISH ARCHAEOLOGICAL REPORTS-S728, 1998 Natural Catastrophes
During
Bronze Age Civilisations: Archaeological, geological,
astronomical and
cultural perspectives. Edited by Benny J. Peiser, Trevor Palmer
and
Mark E. Bailey. ISBN 0 86054 916 X., 252 pp., 39 photos, 46
figures, 13
tables, £36.00. [Archaeopress, Oxford]
================
(2) DIARY OF A LEONIDS MISSION
From the BBC
Tomorrow's World <http://www.bbc.co.uk/tw/9899/981125news.shtml>
This year’s Leonid meteor storm promised damage to
satellites and a
celestial show for the world. For scientists it was a change to
fly
through a comet tail without mounting an expensive planetary
rocket
mission.
The tiny specks of cometary dust and dirt which came hurtling
through
the atmosphere at over 70 kilometres a second carried with them
priceless clues to the origin of the solar system and even life
on
Earth. The storm was predicted to break in the early morning of
Wednesday 18th November as Earth crossed the plane of the comet.
On
Monday night, 13 hours before, across the UK reports were coming
in of
bright fire balls streaking across the night sky.
Across the globe people counted the meteors, and recorded their
colours. High above our heads fleets of satellites were turned
away
from the storm and instructed to report back the number of times
they
were hit. Even the tiny wobbles on the Hubble telescope were
recorded.
Out of Japan NASA sent two planes packed with astronomers and
instruments to chase the storm. BBC science journalist Chris
Riley
joined the flight. His mission diary below documents NASA’s
airborne
expedition out of Okinawa.
A complete version of this diary can be found on the BBC
Tomorrow's
World Website. <http://www.bbc.co.uk/tw/9899/981125news.shtml>
=======================
(3) IS THIS HOW EVOLUTION WORKS? HEAT SHOCK PROTEINS TRIGGER
GENETIC
MUTATION IN RESPONSE TO ENVIRONMENTAL
CATASTROPHES
From the BBC
http://news.bbc.co.uk/hi/english/sci/tech/newsid_222000/222096.stm
By BBC News Online Science Editor Dr David Whitehouse
Scientists have discovered what they believe may be the molecular
basis
of evolution.
They may have found out what actually happens to an organism's
genes
that enables its offspring to adapt and change - that is to
evolve into
new types of living creatures.
The researchers at the University of Chicago say that although an
organism's DNA is changing over time, many of the individual,
small
genetic variations just accumulate and only become noticeable
when that
organism is under environmental stress.
You can look at it this way: while an animal may be perfectly
adapted
to its environment, behind the scenes redundant copies of its
genes are
mutating.
Only when the creature's environment alters and it needs to adapt
to
the changing conditions do these mutations come to the fore.
Essence of evolution
Most mutations will be harmful and will not help the creature
survive
better. But some mutations just might provide an edge.
This is the essence of evolution - creatures have to adapt to
changing
conditions. Those that have an edge will survive - those that do
not
will perish.
"For the first time we have a molecular mechanism that
explains how
organisms that have stuck to the same shape for eons can evolve
new
traits that help them adapt to changing conditions," says
Susan
Lindquist, professor of molecular genetics & cell biology at
the
University of Chicago.
The way cells do this is by using molecules called heat shock
proteins,
in particular Hsp 90. Usually this molecule helps other molecules
in
the cell to cope with heat.
But when an organism is under particular stress and has to cope
with a
changing environment, it appears that Hsp 90 gets called away
from its
normal duties and many of the genetic mutations that had hitherto
been
masked suddenly break out.
These can then be passed onto the organism's offspring to produce
changes in body plan.
New environment
"This sounds like a very bad thing, and no doubt it is for
most of the
individuals," says Lindquist. "But for some, the
changes might be
beneficial for adapting to a new environment."
Lindquist and Suzanne Rutherford, a postdoctoral fellow,
demonstrated
that reducing levels of Hsp 90 allowed natural genetic
abnormalities
hidden in fruit fly populations to suddenly appear.
They produced flies with eyes of different colours; deformed in
shape
or absent; flies with misshapen legs; flies with small or absent
wings,
and so on.
Lindquist speculates that Hsp 90 may be a key player in
controlling the
alternation between long periods of genetic stability and the
sudden
bursts of change seen in the fossil record during times when the
Earth
was undergoing major climate changes.
"The way that Hsp 90 covers and uncovers hidden genetic
variations
provides a very plausible molecular mechanism for evolution, but
proving that it actually works over long timescales will be no
easy
task," she says.
Copyright 1998, BBC
============
(4) NEW TUNGUSKA PAPER
From Duncan Steel <dis@a011.aone.net.au>
wrote:
Dear Benny,
Members of this list may find the following paper of interest:
Marek Zbik, "Historical Notes on the Tunguska Cosmic
Catastrophe",
Bulletin of the Polish Academy of Sciences: Earth Sciences,
volume 45, No.2-4, pp.211-238 (1997).
Duncan Steel
====================
(5) ACTIVITY PROFILE OF THE 1998 LEONIDS
From Rainer Arlt <rarlt@aip.de>
I M O S h o w e r C i r c u l a r
Activity profile of the 1998 LEONIDS
--OVERVIEW
A first population index and ZHR profile of the 1998 return of
the
Leonids is given below. The population index r represents the
increase
of meteor numbers towards fainter magnitudes. A small value means
a
high proportion of bright meteors. The profile shows low r-values
between solar longitudes 233.9 and 235.5 (Nov 16, 11h and Nov 18,
01h
UT), except for a short period of high r-value at 235.26 (Nov 17,
19h15m UT; all long-itudes refer to eq. J2000).
The low population index is typical for the background component
of the Leonid meteoroid stream being rich in bright meteors.
Predictions were given for the storm component of the stream.
The strength of this component, which is formed by freshly
ejected
material from the parent comet 55P/Tempel-Tuttle, can hardly be
estimated in advance. A young meteoroid stream component is rich
in faint meteors. The increase of r at the time of storm pre-
diction hints on the presence of this component.
The ZHR profile shows a broad maximum centred at solar longitude
234.5 (Nov 17, 01h30m UT) with an average ZHR of 260. The full
width at half maximum is about 16 hours. The 'storm component'
exhibits an enhancement at the declining part of the background
activity. The peak time of this component lies between 235.3 and
235.4 (Nov 17, 20h20m and 22h30m UT).
The maximum ZHR is lower than what one might have expected after
the excited reports about the fireball night Nov 16-17. However,
there is actually no report giving 500 _recorded_ meteors in an
hour. Rates of 1000 or 2000 are obviously based on extrapolations
or sums of several observers.
The strong background component before the 'storm component'
resembles the appearance of the 1965 Leonids, one year before
the 1966 storm. The prospects for 1999 may be evaluated
comparing the 1998 Leonid data with previous Leonid outbursts
and their 'year before'.
--DATA SECTION
The population index and ZHR profiles given below are based on
the following observers:
Ghazalaha Al-Abed (ABEGH), Iyad Ahmad (AHMIY), Ahmad Al-Niamat
(ALNAH),
Rainer Arlt (ARLRA), Joseph D. Assmus (ASSJO), Zaid Ata (ATAZA),
Jlia Babina (BABJL), Ana Bankovic (BANAN), Rony Barry (BARRO),
Luis R. Bellot (BELLU), Felix Bettonvil (BETFE), Neil Bone
(BONNE),
Mark Borg (BORMR), Michael Boschat (BOSMI), Joana M. Brunet
(BRUJO),
Marija Cajetinac (CAJMA), Arturo Carvajal R. (CARAR), Tal Carmon
(CARTA),
Andrew Casely (CASAN), Matthew Collier (COLMA), Tim Cooper
(COOTI),
Uros Cotar (COTUR), Stefano Crivello (CRIST), Hani Dalee (DALHA),
Luigi d'Argliano (DARLU), Mark Davis (DAVMA), Benoit Dejust
(DEJBE),
Vincent Desmarais (DESVI), Peter Detterline (DETPE), Elena
Dimovski
(DIMEL), John Drummond (DRUJO), Tonis Eenmae (EENTO), Maurizio
Eltri
(ELTMA), Frank Enzlein (ENZFR), Tamas Fodor (FODTA), Keiiti Fukui
(FUKKE), Nobuyuki Fukuda (FUKNO), Ofer Gabzo (GABOF), George W.
Gliba
(GLIGE), Orly Gnat (GNAOR), Shelagh Godwin (GODSH), Amit Gokhale
(GOKAM),
Sagar Gokhale (GOKSA), Yeshodhan Gokhle (GOKYE), Alexandra Golova
(GOLAL),
Prerana Gore (GORPA), Roberto Gorelli (GORRO), Michal Haltuf
(HALMI),
Takema Hashimoto (HASTA), Roberto Haver (HAVRO), Kim Hay (HAYKI),
Amera Hemsy (HEMAM), Kamil Hornoch (HORKM), Daiyu Ito (ITODA),
Kiyoshi Izumi (IZUKI), Helle Jaaniste (JAAHE), Vibor Jelic
(JELVI),
Carl Johannink (JOHCA), Ivan Jokic (JOKIV), Kevin Jones (JONKE),
Javor Kac (KACJA), Primoz Kajdic (KAJPR), D. Kalayda (KALDU),
Dmitrij Karkach (KARDM), Niladri Kar (KARNI), Kenya Kawabata
(KAWKE),
Srdjan Keca (KECSR), Akos Kereszturi (KERAK), Noor Al-Khateeb
(KHANO),
Mark Kidger (KIDMA), Kevin Kilkenny (KILKE), Khalil Konsul
(KONKH),
Marija Kotur (KOTMA), Jakub Koukal (KOUJA), Nikola Kresojevic
(KRENI),
Tom Kucharski (KUCTO), Brigitte Kuneth (KUNBR), Werfried Kuneth
(KUNWE),
Zsolt Lantos (LANZS), Anna S. Levina (LEVAN), Mihir Limaye
(LIMMH),
Vladimir Lukic (LUKVL), Robert Lunsford (LUNRO), Mirjana Malaric
(MALMR),
Katuhiko Mameta (MAMKA), David Martinez Delgado (MARDA), Pierre
Martin
(MARPI), Takuya Maruyama (MARTA), Antonio Martinez (MARTI),
Yukihisa Matumoto (MATYU), Alastair McBeath (MCBAL), Stephen
McCann
(MCCST), Lukas Mecir (MECLU), Mark Mikutis (MIKMR), Ana
Milovanovic
(MILAA), Dragan Milisavljevic (MILDR), Iris Miljacki (MILIR),
Hidekatu Mizoguchi (MIZHI), Amruta Modani (MODAM), Sirko Molau
(MOLSI),
William Morgan (MORWI), Darshan Mundada (MUNDA), Sin Nakayama
(NAKSI),
Koji Naniwada (NANKO), Sven Nather (NATSV), Dalibor Nikolic
(NIKDA),
Prakash Nitsure (NITPR), Mohammad Odeh (ODEMO), Ibrahim Odwan
(ODWIB),
Eran Ofek (OFEER), Hiroyuki Okayasu (OKAHI), Masayuki Oka
(OKAMA),
Dragana Okolic (OKODR), Kazuhiro Osada (OSAKA), Ketan Pendse
(PENKE),
Alfredo Pereira (PERAF), Dusan Perovic (PERDU), Suyin
Perret-Gentil
(PERSU), Furio Pieri (PIEFU), Mila Popovic (POPMI), Dubravko
Potkrajac
(POTDU), Tushar Purohit (PURTU), Ina Rendtel (RENIN), Jurgen
Rendtel
(RENJU), Francisco Rodriguez Ramirez (RODFR), Juan Rodriguez
(RODJU),
Victor Ruiz Ruiz (RUIVI), K.V. Sankaranarayanan (SANKV), Shashank
Shalgar (SHASH), Brian Shulist (SHUBR), Hiroyuki Sioi (SIOHI),
Vesna Slavkovic (SLAVE), James N. Smith (SMIJN), Manuel Solano
Ruiz
(SOLMA), George Spalding (SPAGE), Ulrich Sperberg (SPEUL), Mark
Stafford (STAMA), Enrico Stomeo (STOEN), Niko Stritof (STRNI),
David
Swann (SWADA), Eva Szabados (SZAEV), Richard Taibi (TAIRI),
Masaaki
Takanasi (TAKMA), Mika Takanasi (TAKMI), Khaled Tell (TELKH),
Istvan
Tepliczky (TEPIS), Kazumi Terakubo (TERKA), Neelima Thatte
(THANE),
Danilo Tomic (TOMDA), Yasuhiro Tonomura (TONYA), Michael Toomey
(TOOMI),
Gabrijela Triglav (TRIGA), Josep M. Trigo Rodriguez (TRIJO),
Mihaela
Triglav (TRIMI), Anne van Weerden (VANAE), Erwin van Ballegoy
(VANER),
Miquel A. Villalonga Vidal (VILMQ), Catarina Vitorino (VITCA),
Marija Vlajic (VLAMA), Maja Vuckovic (VUCMJ), Barbara Wilson
(WILBA),
George Zay (ZAYGE).
-----------------------------------------
Date Time Solarlong ZHR +- nLEO
nOBS
-----------------------------------------
Nov 14 2000 232.266 10.1 2.4
16 4
Nov 15 0830 232.789 20.8 6.6
9 1
Nov 15 2130 233.331 17.3 2.0
73 12
Nov 16 0030 233.455 8.5 0.9
90 25
Nov 16 0330 233.579 6.3 0.9
53 16
Nov 16 1030 233.887 26.9 2.4
124 6
Nov 16 1400 234.033 40.8 3.3
155 7
Nov 16 1840 234.227 121.3 11.4 113 8
Nov 16 1910 234.251 140.6 8.4 276 16
Nov 16 2050 234.315 162.0 6.1 706 25
Nov 16 2200 234.361 163.8 4.8 1188 31
Nov 16 2320 234.420 211.4 4.2 2569 57
Nov 17 0030 234.471 241.9 3.4 4992 127
Nov 17 0130 234.511 256.7 3.1 7017 176
Nov 17 0230 234.555 252.2 3.0 7190 175
Nov 17 0330 234.598 243.0 3.3 5451 129
Nov 17 0430 234.639 239.7 4.2 3222 66
Nov 17 0620 234.711 202.0 5.4 1415 35
Nov 17 0720 234.756 188.7 5.3 1265 36
Nov 17 0840 234.811 166.8 4.1 1650 41
Nov 17 0930 234.848 158.8 4.1 1470 35
Nov 17 1040 234.897 135.2 4.3 985 24
Nov 17 1130 234.931 125.0 5.7 483 11
Nov 17 1620 235.131 100.7 4.7 450 14
Nov 17 1700 235.164 101.0 3.3 924 28
Nov 17 1810 235.212 105.1 2.6 1613 47
Nov 17 1910 235.255 111.1 2.5 1996 62
Nov 17 2020 235.300 120.0 3.2 1392 51
Nov 17 2120 235.344 118.1 4.5 674 32
Nov 17 2200 235.373 127.2 7.9 260 11
Nov 18 0010 235.462 45.5 1.9 549 36
Nov 18 0110 235.505 46.7 1.3 1347 80
Nov 18 0230 235.559 44.0 1.4 983 55
Nov 18 0600 235.705 33.2 1.7 375 22
Nov 18 0800 235.791 33.3 1.9 298 19
Nov 18 0940 235.862 36.2 2.9
160 8
Nov 18 1710 236.180 32.6 6.7
23 3
Nov 18 1840 236.239 41.9 2.7 235 13
Nov 18 1940 236.281 40.1 2.5 254 13
Nov 18 2320 236.434 16.5 2.1
63 7
Nov 19 0100 236.505 13.5 1.8
53 7
Nov 19 0130 236.526 20.7 3.6
32 3
Nov 20 0800 237.809 30.1 6.3
22 2
-----------------------------------------
Solar longitudes refer to eq. J2000, 'nLEO' is the number of
Leonids involved in the average, 'nOBS' is the number of
observing periods averaged. ZHRs were computed with the follow-
ing population index profile:
-------------------------------------
Date Time Solarlong r
+- nLEO
-------------------------------------
Nov 15 1730 233.170 2.420 0.270 63
Nov 16 1130 233.919 1.307 0.073 117
Nov 16 1600 234.113 1.382 0.044 900
Nov 16 1920 234.250 1.601 0.172 833
Nov 16 2240 234.390 1.271 0.025 1873
Nov 17 0020 234.465 1.228 0.012 5947
Nov 17 0200 234.535 1.275 0.013 8378
Nov 17 0320 234.591 1.350 0.019 4702
Nov 17 0620 234.717 1.440 0.043 1779
Nov 17 0900 234.827 1.421 0.045 2076
Nov 17 1020 234.881 1.417 0.058 863
Nov 17 1620 235.130 1.940 0.283 162
Nov 17 1900 235.245 2.038 0.176 660
Nov 17 1920 235.261 1.988 0.089 1430
Nov 17 1930 235.268 1.921 0.086 1014
Nov 17 2200 235.373 1.295 0.013 45
Nov 17 2310 235.421 1.394 0.042 188
Nov 18 0020 235.467 1.534 0.042 586
Nov 18 0100 235.501 1.620 0.048 658
Nov 18 0220 235.553 1.970 0.204 315
Nov 18 0800 235.790 1.802 0.108 279
Nov 18 1720 236.184 1.982 0.186 272
Nov 18 1900 236.257 2.160 0.122 261
Nov 18 2300 236.433 2.106 0.218 65
-------------------------------------
The zenithal exponent was gamma=1.0; a re-computation with
gamma=1.4 did not produce significantly different results.
Observations with radiant elevations lower than 20 degrees
or total corrections greater than 5.0 were excluded from the
averages.
More observational reports were received from
Andras Adrovicz, Farrahzadi Azzadeh, Bozorgi Behnaz, Worachate
Boonplod, Ravi Brahmavar, Diadina Cotte, Szillard Csizmadia, Marc
de Lignie, David Dickinson, Alipour Elnaz, David Farkas, Azeemlu
Fatemeh, Katalin Hidasi, Brujerdi Hoda, Peter Horvath, Hyabanyan
Hossein, Yu Ji-hong, Timo Kinnunen, Csaba Lendvai, Doug Little,
Keith Little, Paul Maley, Maleki Mania, Fred Mason, Dan McIntosh,
Karoly Mikics, Masjedi Morad, Adam Nemeth, Shigemi Numazawa,
Andras
Petyus, Adam Pozsik, Rezaai Reza, Qi Rui, Khoeini Saloumeh,
Moghimi
Saman, Debasis Sarkar, Lamei Sepideh, Kharrazi Sharmin, Amy
Shelton,
Ghassemi Sima, Szandor Szabo, Darren Tabbot, Hezareh Talayeh,
Zoltan Tarnoki, Zoltan Toth, Zoltan Zelko, Sajjadi Zeynab Wu
Zhi-wei
---
Rainer Arlt, 1998 November 26, 11h UT.
International Meteor Organization
http://www.imo.net
---
==================
(6) COMETARY OUTBURSTS AT LARGE HELIOCENTRIC DISTANCES
P. Gronkowski*) & J. Smela: The cometary outbursts at large
heliocentric distances. ASTRONOMY AND ASTROPHYSICS, 1998,
Vol.338,
No.2, pp.761-766
*) PEDAGOG UNIVERSITY, INST PHYS, RZESZOW, POLAND
A model is presented explaining changes in cometary
brightness during
an outburst at large heliocentric distances. It is shown that a
combination of the following effects can explain the main
characteristics of outburst at large heliocentric
distances: the
specific exothermic processes in cometary nucleus (as the HCN
polymerisation and the crystallization of the water amorphous
ice,
connected with the ejection of the large quantities of dust) and
the
sublimation of CO or CO2 from the comet's nucleus. The obtained
results
are in good agreement with observations. Copyright 1998,
Institute for
Scientific Information Inc.
===============
(7) A DOUBLE NUCLEUS OF COMET EVANS-DRINKWATER
Z. Sekanina: A double nucleus of comet Evans-Drinkwater (C/1996
J1).
ASTRONOMY AND ASTROPHYSICS, 1998, Vol.339, No.1, pp.L25-L28
CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA,91109
The nucleus of comet C/1996 J1, whose duplicity was first
detected in
early May 1997, similar to 4 months after perihelion, is found to
have
split nontidally similar to 70 days before perihelion at 1.65 AU
from
the Sun. The secondary nucleus, discovered when in outburst and
subsequently observed for 8-1/2 months, had separated from the
primary
nucleus at a rate of 1.7 m/s and drifted away from it with a
radial
nongravitational deceleration of similar to 31 x 10(-5) the Sun's
attraction, typical for the short-lived companions. At the time
of
splitting, this dynamically new comet was near conjunction with
the Sun
and therefore unobservable from Earth. In late 1997 and early
1998,
when last seen, the companion was greater than or similar to 100
times
fainter relative to the primary component than it had been when
first
reported. Copyright 1998, Institute for Scientific Information
Inc.
===================
(8) WATER ICE IN COMET HALE-BOPP
E. Lellouch*), J. Crovisier, T. Lim, D. Bockelee Morvan, K.
Leech,
M.S. Hanner, B. Altieri, B. Schmitt, F. Trotta, H.U. Keller:
Evidence
for water ice and estimate of dust production rate in comet
Hale-Bopp
at 2.9 AU from the Sun. ASTRONOMY AND ASTROPHYSICS, 1998,
Vol.339,
No.1, pp.L9-L12
*) PARIS OBSERVATORY, F-92195 MEUDON, FRANCE
We report observational evidence for water ice in comet C/1995 O1
(Hale-Bopp) when it was at 2.9 AU from the Sun, from emission
features
at 44 and 65 mu m, and possibly an absorption feature at 3.1 mu
m,
observed with ISO/LWS and PHT. We find that icy grains have mean
radii
of 15 mu m within a factor of 2, lifetimes of similar to 2 days,
a
temperature of similar to 153 K, and a total mass of similar to 2
x
10(9) kg. From investigation of the continuum spectrum at 43-195
mu m,
we also infer a production rate of large particles (similar to
100 mu
m) dust of about 4 x 10(4) kg s(-1). Copyright 1998, Institute
for
Scientific Information Inc.
----------------------------------------
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