PLEASE NOTE:
*
CCNet 87/2001 - 16 July 2001
---------------------------
"From July 16 through July 22, 1994, pieces of an object
designated
as Comet P/Shoemaker- Levy 9 collided with Jupiter. This [was]
the first
collision of two solar system bodies ever to be observed, and the
effects
of the comet impacts on Jupiter's atmosphere have been simply
spectacular
and beyond expectations. Comet Shoemaker-Levy 9 consisted of at
least 21
discernable fragments with diameters estimated at up to 2
kilometers."
--JPL/NASA
"On the other hand, life could simply have arrived here in a
meteorite from Mars. This idea is "highly plausible --
always supposing
there was life on Mars in the first place", says Professor
Paul
Davies. It's estimated about half a billion Martian rocks
suitable for
carrying living microbes have reached Earth. Some would have
burnt up. But
many would have landed safely, says Davies."
--Deborah Smith, Sydney Morning Herald, 14 July 2001
"Everyone is so busy discovering planets they don't feel
ready to
sit down in committees and decide what to call them,"
laments Helene
Dickel, who chairs the nomenclature committee of the
International
Astronomical Union, the international body that, among other
things,
assigns official names to celestial bodies. Last August, at an
IAU meeting
in Manchester, delegates failed to agree on how to name
extrasolar planets.
The relevant subcommittees are now trying to hammer out an
agreement in
time for the union's next big meeting, in Sydney in 2003. The
planet
hunters have proposed a simple solution: giving the planets
proper
names."
--Tom Standage, The Guardian, 12 July 2001
(1) HERE'S LOOKING AT YOU, EARTHLINGS
Andrew Yee <ayee@nova.astro.utoronto.ca>
(2) PLANETS BY OTHER NAME
Andrew Yee <ayee@nova.astro.utoronto.ca>
(3) COMET LINEAR FLARES AGAIN
Weather News for July, Friday the 13th
(4) ANOTHER SCIENTIFIC EXPEDITION TO TUNGUSKA METEORITE FALL SITE
Ron Baalke <baalke@jpl.nasa.gov>
(5) CANON CITY METEORITE GOES ON DISPLAY
Ron Baalke <baalke@jpl.nasa.gov>
(6) SUCCESSFUL MISSILE INTERCEPT TEST MEANS PLANETARY DEFENSE
MIGHT WORK ONE
DAY, TOO
Space.com, 15 July 2001
(7) GREATER SOLAR ACTIVITY MAY BRING U.S. MORE GRAY DAYS
Goddard Space Flight Center, 12 July 2001
(8) MOON RIVER, FUNKY CHICKENS AND THE MOON HOAX
Matthew Genge <M.Genge@nhm.ac.uk>
(9) A SALUTE TO GENE SHOEMAKER AND A RESOLUTION
Andy Smith <astrosafe@yahoo.com>
(10) KUIPER BELT ABSTRACTS
Kuiper Belt Electronic Newsletter, no.
18, July 2001
=================
(1) HERE'S LOOKING AT YOU, EARTHLINGS
From Andrew Yee <ayee@nova.astro.utoronto.ca>
Sydney Morning Herald, 14 July 2001
[ http://www.smh.com.au/news/0107/14/text/review6.html
]
Saturday, July 14, 2001
Here's looking at you, Earthling
Light and microbes offer new clues in the search for other life
in the
universe, writes Deborah Smith.
The day we discover we are not alone in the universe, it could be
thanks to
the research of a young Australian scientist, Dr Vikki Meadows.
Some
researchers are convinced microbes will be found living on Mars
in the
not-too-distant future. Others wait patiently at their telescopes
and
computers for a much more intelligent ET to call Earth.
But Meadows believes the first sign of life elsewhere could
simply be the
patterns of light emanating from a faraway planet.
Water and a hospitable atmosphere -- and even the existence of
lowly
creatures such as bacteria -- should show up as tell-tale
"biosignatures" in
the planet's radiation, she says.
Meadows heads a team at NASA's Jet Propulsion Laboratory in
California that
has just received an $18million grant to create computer
simulations of a
range of planets and life forms.
"Our theoretical studies will drive the design of the
instruments that will
ultimately look for signs of life," says Meadows, who spoke
at a conference
in Sydney this week to mark the establishment of the Australian
Centre for
Astrobiology, at Macquarie University.
First, however, astronomers will have to locate Earth-like
planets. More
than 60 planets outside our solar system have been discovered in
the past
five years but they are all "hot giants" --
Jupiter-sized gas planets that
sit close to their suns and which are unlikely to sustain life.
Professor Malcolm Walter, director of the new NASA-affiliated
astrobiology
centre, says Australia is a perfect place to study how life
evolved on
Earth, and the kind of creatures that could exist elsewhere.
"We have an abundance of very ancient rocks that preserve
the history of
microbial life on Earth, and we have a number of extreme modern
environments
where we can sample microbes adapted to very different
conditions," he says.
Tiny inanimate organisms may be nowhere near as exciting as
little green
men. But just one discovery of life nearby, "be it only
microbial life",
would resolve the age-old question of whether we are the result
of a rare
chance event, says Dr Jeremy Bailey, of the Anglo-Australian
Observatory, an
organiser of the conference.
"It would show that life forms easily, given a suitable
planet, and would
indicate that we live in a universe teeming with life."
Life on Earth probably sprang up between 4 billion and 3.8
billion years
ago. The oldest fossil evidence of early life was found in
3.5-billion-year-old rocks in the Pilbara region of Western
Australia in
1999. The fossilised egg-carton-shaped structures, called
stromatolites,
were built by ancient bacteria.
Rocks from the same region which were 2.7 billion years old also
revealed
the earliest known existence of organisms from the family to
which we belong
-- the eukaryotes, whose cells have a nucleus. (The other two
families are
bacteria and archaea.)
Last week, Walter added to Australia's notoriety with his team's
discovery
of the world's oldest ecosystem -- 1.5-billion-year-old fossils
of 10 new
species of primitive organisms that floated in a shallow sea once
covering
the Northern Territory.
Walter is helping advise NASA on the best sites on Mars for
seeking fossils
of the microbial life that could also have been abundant there
three to four
billion years ago.
Deposits on the red planet associated with ancient hot springs
would be
leading contenders, because geologists already are good at
detecting these
mineral bodies.
The first extra-terrestrial life forms to be found are likely to
be
"extremophiles", organisms which can withstand extreme
environments, says Dr
Rick Cavicchioli of the University of NSW. He describes the many
varieties
of extremophile bacteria and archaea on Earth as the "bungy
jumpers" of the
microbial world.
"They thrive in ice, boiling water, acid, the water core of
nuclear
reactors, salt crystals, toxic benzene and under pressure
equivalent to two
elephants standing on a 10 cent piece."
Last year's discovery in Western Australia of
3.2-billion-year-old fossils
of microbes that survived in scalding temperatures on the ocean
floor added
weight to a leading theory that the first life forms on Earth
were
heat-loving extremophiles.
"Rather than a warm little pond, the cradle of life may have
been a
sulfurous, subterranean inferno, not unlike a medieval vision of
hell," the
discoverer, Dr Birger Rasmussen of the University of Western
Australia, said
at the time.
All life on Earth is based on DNA, so there must have been one
original
organism -- dubbed the Last Universal Common Ancestor, LUCA --
from whom we
are all descended.
Some genetic analysis places the heat-loving bacteria and archaea
very close
to the beginning of this tree of life. New Zealand scientists,
however, are
leading the challenge to this idea.
They are interested in RNA, rather than DNA -- a single strand of
genetic
code found in all our cells, which DNA uses to makes proteins.
Evidence is
growing that before DNA evolved on Earth, there was an RNA world,
with
organisms that depended on this molecule to reproduce themselves.
Dr Anthony Poole, of Massey University, a speaker at the
astrobiology
conference, says it is possible to reconstruct this world by
looking at the
RNA "relics" found in today's creatures.
The vast amount of relics are found in our family, the
eukaryotes, which
suggests that this line is the oldest.
Bacteria and archaea evolved later, possibly in order to survive
in high
temperatures, Poole's research shows. His conclusion: "LUCA
was not a
thermophile [heat-lover]".
On the other hand, life could simply have arrived here in a
meteorite from
Mars. This idea is "highly plausible -- always supposing
there was life on
Mars in the first place", says Professor Paul Davies, who
gave a public
lecture to launch the centre.
It's estimated about half a billion Martian rocks suitable for
carrying
living microbes have reached Earth. Some would have burnt up. But
many would
have landed safely, says Davies.
Astrobiology had its beginnings in 1996 when NASA scientists
including Dr
Everett Gibson made the momentous announcement that they had
found evidence
of past life on Mars, in a small Martian rock discovered in
Antarctica in
1984.
The finding has been under scientific attack ever since, which is
as
expected, says Walter, because extraordinary claims require
compelling
evidence.
Gibson, a key speaker at the conference, presented research
showing that two
more Martian meteorites contained similar evidence.
"Our hypothesis of possible early life on Mars was presented
five years ago
and today we believe that it stands stronger than when we
originally
presented," he says. "To date, no fatal strikes have
been made on any of the
original lines of evidence."
A major problem for the meteorite find has been that no organisms
small
enough to be responsible for the micro-fossils in it were known
on Earth.
This changed three years ago when Dr Philippa Uwins, of the
University of
Queensland, found microscopic, nanometre-sized organisms living
in sandstone
from five kilometres under the West Australian seabed.
Dubbed nanobes, they are a similar size to the nanobacteria
associated with
the Mars rocks. Uwins's team has succeeded in extracting DNA from
the
controversial nanobes, a major step in eventually determining
what kind of
creatures they are.
NASA has missions planned to search for life on Mars and on
Europa,
Jupiter's icy moon. It is also planning space telescopes that
will be able
to detect Earth-like planets. Maybe we should hope the
instruments Meadows
helps design only detect microbes.
Dr Charles Lineweaver at the University of NSW has calculated
that
terrestrial planets in the universe would be, on average, 1.8
billion years
older than Earth. Some life could have as much as a
seven-billion-year head
start, he says.
IMAGE CAPTION: [ http://www.smh.com.au/news/0107/14/graphics/Rplanet.jpg
] The
discovery of nanobes, below, underlines the theory that life on
Earth first
came from Mars, top. Main photograph taken by the Hubble Space
Telescope on
June 26. Nanobe image: University of Queensland.
Copyright © 2001 Sydney Morning Herald. All rights reserved.
================
(2) PLANETS BY OTHER NAME
From Andrew Yee <ayee@nova.astro.utoronto.ca>
From The Guardian, 12 July 2001
http://www.guardianunlimited.co.uk/Print/0,3858,4220071,00.html
Thursday, July 12, 2001
Planets by other names
There is more to naming a discovery than mere tradition, writes
Tom Standage
By Tom Standage
On a chilly March night in 1781, an amateur astronomer called
William
Herschel stood in his garden in Bath, peered into a home-made
telescope, and
accidentally became the first person in recorded history to
discover a new
planet. The other planets -- Mercury, Venus, Mars, Jupiter and
Saturn, which
are easily visible to the naked eye -- had been known under
various
mythological names since the dawn of humanity. So when it came to
giving his
new planet a name, Herschel decided to break with tradition.
The mythological names favoured by the ancients, he declared,
were
unsuitable "in the present more philosophical era".
Instead, he proposed to
name the new planet Georgium Sidus, or George's star, in honour
of his
patron, King George III. Astronomers across Europe groaned.
Herschel was
brown-nosing; and, worse, it was simply wrong to refer to his
discovery as a
star. Others raced to propose alternative names, including
Astrea, Cybele,
Hypercronius, Minerva, Oceanus and
Neptune. Eventually the planet ended up with three names: the
English stuck
with Georgium Sidus, the French opted for Herschel, and the
Germans gave it
the mythological name Uranus, by which it is still known today.
The first
attempt to name a planet in modern times had degenerated into
farce.
But things are little better today. Since 1995, astronomers have
discovered
more than 60 planets orbiting nearby sun-like stars. The planets
are found
by scrutinising the stars' light for evidence of the
"wobbles" caused by the
gravitational influence of orbiting planets. The discovery of
these
"extrasolar" planets has become so routine that they
are now announced in
batches; the latest lot, announced in April, consisted of 11 new
planets,
more than there are in our own solar system. Dozens more are on
the way:
planets are now being found at an average rate of more than one a
month.
Yet planet hunters have been unable to decide how to name their
finds.
Ironically, given Herschel's choice of name for his planet, the
planets have
also been temporarily named as though they were stars. The first
planet,
found orbiting a star called 51 Pegasi in 1995, has been dubbed
51 Pegasi b.
This is an extension of the scheme used to name binary and
multiple stars,
in which the letter "a" is assigned to the star itself.
In some cases, stars have multiple planets. Upsilon Andromedae,
for example,
has at least three planets, which are called b, c and d in order
of
increasing distance from their parent star. But there problems
with this
scheme. What if another planet is subsequently found orbiting
between c and d?
Introducing a new d, and renaming d to e, would render
meaningless any
scientific papers that refered to the planets by their old names.
So a
number of alternative schemes have been proposed. One is to give
the planets
roman numerals in order of discovery, as is done with the moons
of Jupiter.
Another is to label the planets numerically by distance from, or
time taken
to orbit, their parent stars. However, these quantities are not
always known
accurately, so the names are subject to change.
"Everyone is so busy discovering planets they don't feel
ready to sit down
in committees and decide what to call them," laments Helene
Dickel, who
chairs the nomenclature committee of the International
Astronomical Union,
the international body that, among other things, assigns official
names to
celestial bodies. Last August, at an IAU meeting in Manchester,
delegates
failed to agree on how to name extrasolar planets. The relevant
subcommittees are now trying to hammer out an agreement in time
for the
union's next big meeting, in Sydney in 2003. The planet hunters
have proposed
a simple solution: giving the planets proper names.
Michel Mayor and Didier Queloz, the Swiss astronomers who
discovered 51
Pegasi b, the first extrasolar planet, have proposed naming it
Epicurus,
after the Greek philosopher who first suggested that there might
be a
"plurality of worlds". Geoffrey Marcy, an American
astronomer whose team has
discovered more planets than any other, has suggested the
mythological name
Bellerophon for the planet, after the Greek hero who tamed
Pegasus, the
flying horse.
There is a certain simplicity to this approach. But, says Dr
Dickel, it has
been ruled out because future space missions, such as NASA's SIM
mission and
the European Space Agency's Eddington probe, are expected to find
millions
of planets, and "trying to name millions of objects with
individual names
isn't going to work".
This means that a general-purpose alphanumeric scheme will have
to be
devised. If Herschel were still around, he would surely approve
of the fact
that, in the present more philosphical era, mythological names
will finally
have been abandoned. Or will they? Astronomers still seem
inclined to apply
such names, at least to some planets. So in many ways, little has
changed
since 1781.
[Tom Standage is the author of The Neptune File: Planet
Detectives and the
Discovery of Worlds Unseen (Penguin, £6.99)]
© Guardian Newspapers Limited 2001
============
(3) COMET LINEAR FLARES AGAIN
Space Weather News for July, Friday the 13th
http://www.spaceweather.com
Just yesterday Comet LINEAR (C/2001 A2) was fading from view as
it receded
from Earth. But now the volatile comet is again a naked-eye
object. It's
glowing at about 4th magnitude in the pre-dawn sky with a pair of
tails you
see through binoculars or a modest telescope. Comet LINEAR has a
history of
crumbling then flaring as freshly exposed ice is vaporized by
sunlight. What
will the comet do in the days ahead? See for yourself! Visit
SpaceWeather.com for details.
===========
(4) ANOTHER SCIENTIFIC EXPEDITION TO TUNGUSKA METEORITE FALL SITE
From Ron Baalke <baalke@jpl.nasa.gov>
http://english.pravda.ru/fun/2001/07/15/10167.html
pravda.ru
July 15, 2001
One more scientific expedition has set off from Krasnoyarsk in
Eastern
Siberia to the place where in its time the Tunguska meteorite
fell. A
celestial body of tremendous mass and unknown origin, whose
collision with
the earth happened near the Evenk village of Vanavara on June 30,
1908, is
to this day one of the main mysteries of the 20th century. Now
the
expedition, made up of mostly scientists from Novosibirsk and
Tomsk, is
going to study a new portion of the Tunguska virgin forest land,
taiga. This
land, located nearly 20-25 kilometers away from the place seen
over many
years as the epicenter, has never been seriously examined ever
since. The
expedition will check the version whether or not the Tunguska
meteorite was
a gigantic fragment of an ice comet.
==============
(5) CANON CITY METEORITE GOES ON DISPLAY
From Ron Baalke <baalke@jpl.nasa.gov>
http://www.rockymountainnews.com/drmn/local/article/0,1299,DRMN_15_750375,00.html
'Canon City meteorite' goes on display
Softball-size object that hit garage in '73 to be in Springs
By Todd Hartman
Rocky Mountain News
July 14, 2001
A meteorite that slammed through the roof of a Canon City garage
in 1973
will get its first prominent public display this weekend in
Colorado
Springs. The sneak preview will precede by at least a year the
meteorite's
permanent display in Denver.
Dubbed the "Canon City meteorite," the softball-size
object hit the garage
floor of the house and exploded into pieces. It is one of only
two
meteorites known to have hit a man-made structure in Colorado and
one of
only 35 meteorites to have hit a structure in the United States.
Full story here:
http://www.rockymountainnews.com/drmn/local/article/0,1299,DRMN_15_750375,00.html
=============
(6) SUCCESSFUL MISSILE INTERCEPT TEST MEANS PLANETARY DEFENSE
MIGHT WORK ONE
DAY, TOO
From Space.com, 15 July 2001
http://www.space.com/missionlaunches/missile_test_update_010715.html
U.S. Ballistic Missile-Shield Program Passes Test; Mock Warhead
Destroyed
By Jim Wolf
Reuters
WASHINGTON (Reuters) - The Defense Department shot down a mock
warhead over
the Pacific Ocean late on Saturday in a successful test of a
controversial
anti-ballistic missile defense.
"The kill-intercept was confirmed by all our sensors,"
Air Force Lt. Gen.
Ronald Kadish, head of the Pentagon's Ballistic Missile Defense
Organization, told a news briefing.
But the results would take up to two months to analyze fully and
"in all
probability" some of the test's objectives were unmet, he
said.
Kadish termed it "one step on a journey" toward
building a multilayered
shield against missiles that could be tipped with nuclear,
chemical or
biological warheads.
FULL STORY at
http://www.space.com/missionlaunches/missile_test_update_010715.html
===========
(7) GREATER SOLAR ACTIVITY MAY BRING U.S. MORE GRAY DAYS
From Goddard Space Flight Center, 12 July 2001
http://www.gsfc.nasa.gov/topstory/20010712cloudcover.html
NASA-funded Earth Science researchers have discovered that during
periods of
increased solar activity much of the United States becomes
cloudier,
possibly because the jet stream in the troposphere moves
northward causing
changes to regional climate patterns.
The new study supports earlier findings by suggesting there is a
relationship between increased cloud cover over the United States
and the
solar maximum, the most intense stage of activity on the Sun.
Previous studies have shown that during the solar maximum, the
jet stream in
the Northern Hemisphere moves northward. The jet stream guides
storms and
plays an important role in cloudiness, precipitation and storm
formation in
the United States.
Dr. Petra Udelhofen, a NASA-funded researcher at the Institute
for
Terrestrial and Planetary Atmospheres at the State University of
New York at
Stony Brook, is the lead author of a paper that discusses this
topic,
appearing in the July 1 issue of Geophysical Research Letters.
"Based on these results and because the location of the jet
stream
influences cloudiness," said Udelhofen, "we suggest
that the jet stream
plays an important role in linking solar variability and cloud
cover."
The jet stream is a ribbon of fast-moving air in the upper
troposphere that
blows from west to east. Storms beneath the jet stream follow its
path. A
shift in the jet stream can alter the location of clouds and
precipitation
across the U.S.
The troposphere is the region of the atmosphere that extends from
the
Earth's surface out to about 50,000 feet and is the focus of
local, regional
and global weather research. The stratosphere extends above the
troposphere
to about 150,000 feet and is the region where the ozone layer is
formed.
The Sun's energy output varies over an 11-year cycle, sending
more
ultraviolet radiation towards the Earth during times of increased
activity.
While the Sun's total energy output only varies by about
one-tenth of one
percent between periods of low and high solar activity, the
ultraviolet
radiation that affects ozone production in the stratosphere can
change by
more than 10 percent.
Ultraviolet radiation is absorbed in the Earth's stratosphere and
creates
the protective ozone layer. When the ozone absorbs ultraviolet
radiation, it
warms the stratosphere, which may affect movement of air in the
troposphere
where clouds form.
Solar cycle effects of ultraviolet radiation absorption by ozone
in the
stratosphere, its impact on atmospheric circulation and the
location of
storm tracks have been the subject of recent Earth Science
research.
"Our results show that cloudiness varies on average by about
two percent
between years of solar maximum and minimum. In most parts of the
U.S., cloud
cover is slightly greater in years of solar maximum," noted
Udelhofen.
Though more investigation is needed to better understand just how
changes in
the Sun's ultraviolet energy output is linked to atmospheric
winds, the
study helps people identify potential large-scale mechanisms that
affect
local and regional climates.
Scientists continue to investigate mechanisms that may link solar
variability with weather. These new results support the idea of a
link
between stratospheric chemistry and meteorology, and support
other recent
theoretical studies associated with the impact of stratospheric
chemistry on
climate change and weather.
"It is important for future studies to identify and explain
in detail the
link between solar variability, ozone, the atmospheric
circulation and cloud
cover," Udelhofen said.
This research is part of the NASA Earth Science Enterprise
program, which is
dedicated to understanding how Earth is changing and what
consequences these
changes have for life on Earth.
============================
* LETTERS TO THE MODERATOR *
============================
(8) MOON RIVER, FUNKY CHICKENS AND THE MOON HOAX
From Matthew Genge <M.Genge@nhm.ac.uk>
What happens when you write an article in an attempt to debunk a
widely held
conspiracy theory? One thing is that your email inbox gets very
full
remarkably quickly. Surprisingly most of the feedback and
questions were
lucid and asked whether the Apollo samples could have been
returned by an
unmanned mission similar to the Luna probes. My reply was to
explain that
because the live footage shows the rocks being collected by the
astronauts
NASA would have had to send two missions for every Apollo
mission. The first
would have to be sent in secret to recover the rocks so the
astronauts could
be filmed later collecting them. This sample return mission would
need to
have a rover to collect such a variety of samples and, unlike the
USSR
Lukinod rover, it would have to be robotic since it couldn't be
controlled
from the ground. The rover would also have to be able to collect
core
samples of the lunar regolith a task which is difficult enough
today (the
Beagle II Mars lander designed by the Open University will
achieve this feat
using an ingenious 'thunderbirds-like' mole). The second mission
would, of
course, be the fake mission carrying the prerecorded
communications to be
sent back from the Moon's surface.
Amazingly quite a few people replied to say thank you they were
now
convinced. There is, however, no convincing some people. Even
when we go
back to the Moon and find the flags, rovers, LEMs and the
astronaut's
footprints there will be those who will firmly believe that this
is just one
more twist in the conspiracy. One of these will be the person
whose email
only identified them as "funky chicken" and believes
that I am part of an
international conspiracy covering up everything from crop circles
to
pyramids on Mars.
Finally, one further thing happens after such an article. You
inexplicably
find yourself broadcasting live on radio to Australia, at 3.30 in
the
morning, being interviewed by a man with the typical 'late-night
radio'
voice whilst "Moon river" by Ben E King plays in the
background.
Regards,
Matt Genge
===========
(9) A SALUTE TO GENE SHOEMAKER AND A RESOLUTION
From Andy Smith <astrosafe@yahoo.com>
Hello Benny and CCNet,
As we remember Gene and SL-9 and all of those who have made it
possible for
us to be here and to be aware of the great danger we
face....while there is
still time.. and as we think of those, yet unborn, who are
depending on us
to protect them from KALI; we pray that we will have enough
time to
prepare; that we will strenthen our resolve and sense of urgency;
that we
will be given the governmental and public support needed, around
the world,
to:
(1) identify and track the 100,000 plus dangerous NEO, within the
next few decades (instead of centuries);
(2) to prepare a quick emergency deflection capability and
(3) to develop good civil emergency preparedness plans;
and that we will be more tolerant and respectful of one another
and that we
will find ways to come together, as a single global team, to
successfully
meet this great challenge...in a spirit of mutual respect and
love.
Here is a quick link to the SL-9 Home Page and those great
pix:
http://www.jpl.nasa.gov/sl9/
May GOD Bless and Protect Us All
=========
(10) KUIPER BELT ABSTRACTS
From the Kuiper Belt Electronic Newsletter, no. 18, July 2001
http://www.boulder.swri.edu/ekonews/issues/past/n18/html/
The Size and Albedo of The Kuiper-belt Object (20000) Varuna
D. Jewitt1, H. Aussel1, and A. Evans2
1 Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, Hawaii
96822, USA
2 Department of Physics and Astronomy, SUNY at Stony Brook, Stony
Brook, New
York 11794-3800, USA
Observations over the last decade have revealed the existence of
a large
number of bodies orbiting the Sun beyond Neptune. Known as the
Kuiper-belt
objects (KBOs), they are believed to be formed in the outer
reaches of the
protoplanetary disk around the young Sun, and have been little
altered since
then. They are probably the source of short-period comets. The
KBOs are,
however, difficult objects to study because of their distance
from earth, so
even basic physical properties such as their sizes and albedos
remain
unknown. Previous size estimates came from assuming an albedo
with the
canonical value being 0.04. Here we report simultaneous
measurements of the
thermal emission and reflected optical light of the bright KBO
(20000)
Varuna, which allow us to determine independently both the size
and the
albedo. Varuna has an equivalent circular diameter of D =
900+129-145 km and
a red geometric albedo of pR = 0.070+0.030-0.017. Its surface is
darker than
Pluto's, suggesting that it is largely devoid of fresh ice, but
brighter
than previously assumed for KBOs.
Published in: Nature, 411, 446 (2001 May 24)
For preprints, contact jewitt@ifa.hawaii.edu
or on the web at http://www.ifa.hawaii.edu/faculty/jewitt/varuna.html
----------------------------------------------------------------------------
----
Almost Planet X
S.C. Tegler1 and W. Romanishin2
1 Department of Physics & Astronomy, Northern Arizona
University, Flagstaff,
AZ, 86011, USA
2 Department of Physics & Astronomy, University of Oklahoma,
Norman, OK,
73019, USA
Optical and infrared observations of a bright object in the outer
Solar
System reveal it to be surprisingly large -- almost as big as
Pluto's moon.
It could be the first of many such discoveries.
Published in: Nature, 411, 423 (2001 May 24)
For preprints, contact stephen.tegler@nau.edu
----------------------------------------------------------------------------
----
The Radial Distribution of the Kuiper Belt
C.A. Trujillo1 and M.E. Brown1
1 California Institute of Technology, MS 150-21, Pasadena, CA
91125, USA
We examine the radial distribution of the Kuiper Belt Objects
(KBOs) using a
method that is insensitive to observational bias effects. This
technique
allows the use of the discovery distances of all KBOs,
independent of
orbital classification or discovery circumstance. We verify the
presence of
an outer edge to the Kuiper Belt, as reported in other works, and
we measure
this edge to be at AU given any physically plausible model
of the size
distribution. We confirm that this outer edge is due to the
Classical KBOs,
the most numerically dominant observationally. In addition, we
find that
current surveys do not preclude the presence of a second,
unobserved Kuiper
Belt beyond R = 76 AU.
Published in: The Astrophysical Journal, 554, L95 (2001 June 10)
For preprints, contact chad@gps.caltech.edu
or on the web at
http://www.gps.caltech.edu/~chad/publications/2001-trujillo-brown.pdf
----------------------------------------------------------------------------
----
NICS-TNG Infrared Spectroscopy of Trans-neptunian Objects 2000
EB173 and
2000 WR106
J. Licandro1, E. Oliva1,2, and M. Di Martino3
1 Centro Galileo Galilei & Telescopio Nazionale Galileo, P.O.
Box 565,
E-38700, S/C de La Palma, Tenerife, Spain
2 Osservatorio di Arcetri, Largo E. Fermi 5, I-50125 Firenze,
Italy
3 Osservatorio Astronomico di Torino, I-10025 Pino Torinese,
Italy
We report complete near-infrared (0.9-2.4 m) spectral
observations of
trans-neptunian objects (TNOs) 2000 EB173 and 2000 WR106
collected using the
new Near Infrared Camera Spectrometer (NICS) attached to the
3.56m
Telescopio Nazionale Galileo (TNG). Both spectra are very red and
with a
quite strong and broad drop extending throughout the K band.
However, while
2000 EB173 does not show any evidence of narrow absorption
features, the
spectrum of 2000 WR106 has quite deep water ice absorption at 1.5
and 2.0 m.
Moreover, the latter object is significantly less red than the
former
indicating, therefore, that the surface of 2000 WR106 is
``cleaner'' (i.e.
less processed by particle irradiation) than that of 2000 EB173.
To appear in: Astronomy & Astrophysics
For preprints, contact licandro@tng.iac.es
or on the web at http://www.arXiv.org/abs/astro-ph/0105434
----------------------------------------------------------------------------
----
Analysis of Trans-Neptunian and Centaur Colours: Continuous Trend
or
Grouping?
M.A. Barucci1, M. Fulchignoni1, M. Birlan1, A. Doressoundiram1,
J. Romon1, and H. Boehnhardt2
1 Observatoire de Paris, DESPA, 5, Place Jules Janssens, F-92190
Meudon,
France
2 ESO, Alonso de Cordova 3107, Santiago de Chile, Chile
We report the results of the first statistical analysis of
colours (B-V,
V-R, V-I, and V-J) of the Trans-Neptunian and Centaur
populations. Using the
same statistical techniques applied to define the current
asteroid taxonomy,
we find a continuous spread of the objects between neutral colour
to very
red. Pushing further the analysis, the TNOs may be split into
four groups.
The differences in colour content are interpreted as a
consequence of the
TNOs evolution (i.e. collisional history, space weathering, ...)
Published in: Astronomy and Astrophysics, 371, 1150 (2001 May)
For preprints, contact antonella.barucci@obspm.fr
----------------------------------------------------------------------------
----
Colors and Spectra of Kuiper Belt Objects
David Jewitt1 and Jane Luu2
1 Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, Hawaii
96822, USA
2 Sterrewacht Leiden, Postbus 9513, 2300RA Leiden, The
Netherlands
We present new measurements of the optical colors of Kuiper Belt
Objects,
principally from the Keck 10-m telescope. The measurements
confirm the
existence of a wide spread in the B-V, V-R, and R-I color indices
(Luu and
Jewitt 1996). Relative to the Sun, the Kuiper Belt Objects
exhibit reflected
colors from nearly neutral to very red. The optical and
optical-infrared
(V-J) color indices are mutually correlated, showing the presence
of a
single reddening agent from m to m. On the other hand, we find no
evidence
for linear correlations between the color and absolute magnitude
(a proxy
for size), instantaneous heliocentric distance, semi-major axis,
or with any
other orbital property. In this regard, the Kuiper Belt Objects
differ from
the main-belt asteroids in which strong radial color gradients
exist. We
find no statistically significant evidence for bimodal or other
non-uniform
color distributions, either in our data, or in data previously
reported to
show such evidence. The impact resurfacing hypothesis is
re-examined in the
light of the new color data and is rejected as the primary cause
of the
observed color dispersion. We also present new near-infrared
reflection
spectra of 1993 SC, 1996 TS66, 1999 DE9 and 2000 EB173, taken at
the Keck
and Subaru telescopes. These spectra, combined with others from
the
published literature, provide independent evidence for
compositional
diversity in the Kuiper Belt. Objects 2000 EB173, 1993 SC, and
1996 TS66 are
spectrally bland while 1999 DE9shows solid-state absorption
bands.
To appear in: Astronomical Journal, in press
For preprints, contact jewitt@ifa.hawaii.edu
or on the web at http://www.ifa.hawaii.edu/~jewitt/papers/COLORPAPER
----------------------------------------------------------------------------
----
Photometric Study of Centaurs 10199 Chariklo (1997CU26) and
1999UG5
N. Peixinho1, P. Lacerda2, J.L. Ortiz3, A. Doressoundiram4,
M. Roos-Serote1, and P.J. Gutiérrez3
1 Centre for Astronomy and Astrophysics of the University of
Lisbon/ Lisbon
Astronomical Observatory, Tapada da Ajuda, P-1349-018 Lisbon,
Portugal
2 Leiden Observatory, the Netherlands
3 Instituto de Astrofísica de Andalucía, CSIC, Granada, Spain
4 Paris-Meudon Observatory, France
We present the results of visible broad band photometry of two
Centaurs,
10199 Chariklo (1997CU26) and 1999UG5, from data obtained at the
1.52 meter
telescope of the National Astronomical Observatory at Calar Alto,
Spain,
during 2 separate runs in April 1999 and February 2000 and at the
1.5 meter
telescope of the Sierra Nevada Observatory, Spain, in March of
1999.
For Chariklo, the absolute magnitudes determined from the
February 2000 data
are found to be higher by about 0.27 magnitudes than the average
in the 1999
run. This may indicate long period rotational variability and
possibly a
Gparameter higher than the assumed value of 0.15. From the best
sampled
R-lightcurve obtained in the February 2000 run, no short term
rotational
variability was found. The V-R colours for this object in all
runs are
similar to previously published values. For 1999UG5, colours were
found to
be very red: , and . These results place this object in the
group of the
reddest known bodies in the Solar System. HR and HV are found to
be and
respectively, and its diameter is estimated to be on the order
of km.
Published in: Astronomy and Astrophysics, 371, 753 (2001 May)
For preprints, contact peixinho@oal.ul.pt
----------------------------------------------------------------------------
----
The Rotation Axis of the Centaur 5145 Pholus
Tony L. Farnham1
1 Department of Astronomy, University of Texas, Austin, TX 78712,
USA
We present observations of the Centaur 5145 Pholus from 2000
January to 2000
August. A rotational lightcurve was assembled from both Vand R
measurements,
confirming previous period determinations of 0.416 day but
exhibiting an
amplitude over twice as high as previously measured. This
lightcurve was
then used in conjunction with previously published lightcurves to
solve for
a north pole position of , (prograde rotation) and a
sidereal period of
0.41592560.0000016 day. As part of this analysis, the axial
ratios of Pholus
were found to be a/b=1.8 and b/c=1.0. Color analyses of the data
give an
average V-R color of 0.710.03, which is slightly lower than the
0.75-0.84
range previously seen. This difference, combined with the fact
that we see
color variations as a function of rotation, suggest that Pholus'
northern
hemisphere contains bluer features than are seen in its southern
hemisphere.
To appear in: Icarus
For preprints, contact: farnham@astro.as.utexas.edu
or on the web at: http://zinfandel.as.utexas.edu/~farnham/pubs.html
----------------------------------------------------------------------------
----
Short Term Variability of Centaur 1999 UG5
P.J. Gutiérrez1, J.L. Ortiz1, E. Alexandrino2,
M. Roos-Serote2, and A. Doressoundiram3
1 Instituto de Astrofísica de Andalucía. Aptd 3004, 18080
Granada. Spain
2 Lisbon Astronomical Observatory. Tapada da Ajuda, 1349-018
Lisbon,
Portugal
3 Paris-Meudon Observatory, France
A lightcurve of Centaur 1999 UG5 from R-band CCD images taken at
the Calar
Alto 1.52 m and La Palma 3.5 m TNG telescopes is presented. The
lightcurve
shows noticeable changes in brightness. Small activity outbursts
do not
appear to be the cause of the brightness changes because no coma
was
detected after coadding all the images. Thus, the changes in
brightness are
interpreted as being caused by rotational variability. A
periodogram
analysis of the lightcurve reveals significant peaks from 13.0 h
to 13.8 h,
with a confidence level exceeding 99.9%. The maximum spectral
power
corresponds to 13.25 h. The overall shape of the lightcurve can
be explained
by an irregular object rotating once per 26.5 h, but other
possibilities
exist. Assuming an ellipsoid shape for the rotating body,
the mag amplitude
of the lightcurve implies a minimum axial ratio of 1.25. The mean
absolute
magnitude in V band was found to be assuming a typical
phase parameter
G=0.15. This implies a diameter of 55.3 km for the object,
provided that a
typical albedo of 0.04 is assumed. The colours of 1999 UG5were
found to be ,
, and .
Published in: Astronomy and Astrophysics, 371, L1 (2001 May)
For preprints, contact pedroj@iaa.es
or on the web at
http://www.edpsciences.fr/articles/aa/abs/2001/19/aadb271/aadb271.html
----------------------------------------------------------------------------
----
Search for CO Gas in Pluto, Centaurs and Kuiper Belt Objects
at Radio Wavelengths
D. Bockelée-Morvan1, E. Lellouch1, N. Biver1,
G. Paubert2, J. Bauer3, P. Colom1, and D.C. Lis4
1 Observatoire de Paris, 5 place Jules Janssen, F-92195, Meudon
Cedex,
France
2 Instituto de Radioastronomía Millimétrica, Avenida Divina
Pastora 7,
Núcleo Central, 18012 Granada, Spain
3 Institute for Astronomy, University of Hawaii, 2680 Woodlawn
Dr.,
Honolulu, HI 96822, USA
4 Division of Physics, Mathematics and Astronomy, California
Institute of
Technology, MS 320-47, Pasadena, CA 91125, USA
We have searched for several rotational lines of CO in the
Pluto-Charon
system, Centaurs (Chiron, Pholus, Nessus, Asbolus, Chariklo and
1998 SG35)
and Kuiper Belt objects (1994 TB, 1996 TL66, 1996 TO66, 1996 TP66
and 1998
WH4). The observations were performed with the 30 m telescope of
the
Institut de Radioastronomie Millimétrique for Pluto/Charon, and
with the
James Clerk Maxwell Telescope and Caltech Submillimeter
Observatory for
Centaurs and Kuiper Belt objects. A tentative 4.5- J(2-1) CO line
is present
in the Pluto/Charon spectrum, which requires further
confirmation. Assuming
that Charon does not contribute to the CO emission, an upper
limit of 1.2%
and 7% is obtained for the CO/N2 mixing ratio in Pluto's
atmosphere, using
the atmospheric thermal structure derived from the Stansberry et
al. (1994,
Icarus 111, 503) and Strobel et al. (1996, Icarus 120, 266)
models,
respectively. These upper limits are more constraining (by more
than a
factor of 6) than the upper limits reported by Young et al.
(2001, Icarus,
in press) from near-IR spectroscopy. None of the Centaurs or
Kuiper Belt
objects (KBO) were detected in CO. The CO production rate upper
limit
obtained for Chiron (3-5 mol s-1) over 1998-2000 years is a
factor of 10
lower than the CO production rate derived from the marginal CO
detection
obtained in June 1995 by Womack & Stern (1999, Astron.
Vestnik 33, 216),
using same modelling of CO emission. Upper limits obtained for
other
Centaurs are typically 1028 mol s-1
To appear in: Astronomy & Astrophysics
For preprints, contact dominique.bockelee@obspm.fr
----------------------------------------------------------------------------
----
Discovery of Water Vapor Around IRC+10216 as Evidence for Comets
Orbiting
Another Star
Gary J. Melnick1, David A. Neufeld2, K.E. Saavik Ford2,
David J. Hollenbach3, and Matthew L.N. Ashby1
1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street,
Cambridge,
Massachusetts 02138, USA
2 Department of Physics & Astronomy, The Johns Hopkins
University, 3400 N.
Charles Street, Baltimore, Maryland 21218, USA
3 NASA/Ames Research Center, Moffett Field, California 94035, USA
Since 1995, planets with masses comparable to that of Jupiter
have been
discovered around approximately 60 stars. These planets have not
been seen
directly, but their presence has been inferred from the small
reflex motions
that they gravitationally induce on the star they orbit; these
motions
result in small periodic wavelength shifts in the stellar
spectrum. The
presence of analogues of the smaller bodies in our Solar System
cannot,
however, be determined using this technique, because the induced
reflex
motions are too small-so an alternative approach is needed. Here
we report
the observation of circumstellar water vapour around the ageing
carbon star
IRC+10216; water is not expected in measurable quantities around
such a
star. The only plausible explanation for this water is that the
recent
evolution of IRC+10216, which has been accompanied by a
prodigious increase
in its luminosity, is causing the vaporization of a collection of
orbiting
icy bodies-a process considered in an earlier theoretical study.
Published in: Nature, 412, 160 (2001 July 12)
For preprints, contact gmelnick@cfa.harvard.edu
or on the web at http://sao-www.harvard.edu/swas/pr010711.html
-------------------------------------------------------------------
THE CAMBRIDGE-CONFERENCE NETWORK (CCNet)
--------------------------------------------------------------------
The CCNet is a scholarly electronic network. To
subscribe/unsubscribe,
please contact the moderator Benny J Peiser <b.j.peiser@livjm.ac.uk>.
Information circulated on this network is for scholarly and
educational use
only. The attached information may not be copied or reproduced
for
any other purposes without prior permission of the copyright
holders. The
fully indexed archive of the CCNet, from February 1997 on, can be
found at
http://abob.libs.uga.edu/bobk/cccmenu.html
DISCLAIMER: The opinions, beliefs and viewpoints expressed in the
articles
and texts and in other CCNet contributions do not
necessarily reflect the
opinions, beliefs and viewpoints of the moderator of this
network.
