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Offline neilep

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How to steal a million stars?

Posted: February 11, 2006

Based on observations with European Southern Observatory's Very
Large Telescope, a team of Italian astronomers reports that the
stellar cluster Messier 12 must have lost to our Milky Way galaxy
close to one million low-mass stars.


This photo shows the centre of the globular cluster
 Messier 12 as observed with the FORS-1 multi-mode instrument on
ESO's Very Large Telescope. Credit: ESO

"In the solar neighbourhood and in most stellar clusters, the least
massive stars are the most common, and by far", said Guido De Marchi
(ESA), lead author of the study. "Our observations with ESO's VLT
show this is not the case for Messier 12".

The team, which also includes Luigi Pulone and Francesco Paresce
(INAF, Italy), measured the brightness and colours of more than
16,000 stars within the globular cluster Messier 12 with the FORS1
multi-mode instrument attached to one of the Unit Telescopes of
ESO's VLT at Cerro Paranal (Chile). The astronomers could study
stars that are 40 million times fainter than what the unaided eye
can see (magnitude 25).

Messier 12 is one of about 200 globular clusters known in our
Galaxy. These are large groupings of 10,000 to more than a million
stars that were formed together in the youth of the Milky Way, about
 12 to 13 billion years ago. Globular clusters are a key tool for
astronomers, because all the stars in a globular cluster share a
common history. They were all born together, at the same time and
place, and only differ from one another in their mass. By accurately
 measuring the brightness of the stars, astronomers can determine
their relative sizes and stage of evolution precisely. Globular
clusters are thus very helpful for testing theories of how stars

An artist's impression of the orbit of the globular
 cluster Messier 12 in the Milky Way. Due to gravitational
disruption, this cluster continuously loses stars, in particular
light ones. This process is enhanced when it passes through the
central plane in which most of the Galaxy's stars and nebulae are
located. The cluster emerges in a less dense state after such a
passage. The stars that are lost move on in orbits similar to that
of the cluster and populate the halo of the Milky Way. Credit: ESO


Located at a distance of 23,000 light years in the constellation
Ophiuchus (The Serpent-holder), Messier 12 got its name by being the
12th entry in the catalogue of nebulous objects compiled in 1774 by
French astronomer and comet chaser Charles Messier. It is also known
to astronomers as NGC 6218 and contains about 200 000 stars, most of
 them having a mass between 20 and 80 percent of the mass of the

"It is however clear that Messier 12 is surprisingly devoid of low-
mass stars", said De Marchi. "For each solar-like star, we would
expect roughly four times as many stars with half that mass. Our VLT
observations only show an equal number of stars of different

Globular clusters move in extended elliptical orbits that
periodically take them through the densely populated regions of our
Galaxy, the plane, then high above and below, in the ‘halo'. When
venturing too close to the innermost and denser regions of the Milky
Way, the ‘bulge', a globular cluster can be perturbed, the smallest
 stars being ripped away.

"We estimate that Messier 12 lost four times as many stars as it
still has", said Francesco Paresce. "That is, roughly one million
stars must have been ejected into the halo of our Milky Way".

The total remaining lifetime of Messier 12 is predicted to be about
 4.5 billion years, i.e. about a third of its present age. This is
 very short compared to the typical expected globular cluster's
lifetime, which is about 30 billion years.

The same team of astronomers had found in 1999, another example of a
globular cluster that lost a large fraction of its original content.

The scientists hope to discover and study many more clusters like
these, since catching clusters while being disrupted should clarify
the dynamics of the process that shaped the halo of our home galaxy,
 the Milky Way.


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Offline neilep

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Spacecraft spots powerful Saturn storm at night
Posted: February 14, 2006

Following the recent detection of Saturnian radio bursts by NASA's
Cassini spacecraft that indicated a rare and powerful atmospheric
storm, Cassini imaging scientists have spotted the storm in an
unlikely fashion: they looked for it in the dark.

This image shows a rare and powerful storm on the
night side of Saturn. Light from Saturn's rings (called "ringshine")
 provided the illumination, allowing the storm and other cloud
features to be seen. Credit: NASA/JPL/Space Science Institute
Download larger image version here

When lightning-generated radio noise from the storm was detected by
Cassini on January 23, the spacecraft was at a place in its orbit
where it was unable to image the sunlit side of Saturn. Instead,
 imaging scientists searched for the southern hemisphere storm in
images of the planet's night side. Fortunately, the small amount of
sunlight reflecting off Saturn's rings and illuminating the night
side is enough to make features in the atmosphere visible.

The storm is located on the side of Saturn that faces the spacecraft
when the radio emissions are detected; Cassini does not observe the
radio emissions for half a Saturnian day when the storm is on the
planet's other side.

The latitude of the new storm matches that of the "Dragon storm,"
which was a powerful emitter of radio noise and was imaged by
Cassini in 2004. It lies in a region of the southern hemisphere
referred to as "storm alley" by scientists because of the high level
of storm activity observed there by Cassini. The storm's north-south
dimension is about 3,500 kilometers (2,175 miles).

"It's really the only large storm on the whole planet," says Andrew
Ingersoll, a member of the Cassini imaging team. "It's in the right
place and it appeared at the right time to match the radio
emissions, so it has to be the right storm," he said.

The storm's north-south dimension is about 3,500
kilometers (2,175 miles); it is located at minus 36 degrees
(planetocentric) latitude and 168 degrees west longitude. This
places it on the side of the planet that faces the spacecraft when
the radio emissions are detected; the radio emissions shut down for
half a Saturnian day when the storm is on the other side. Credit:
 NASA/JPL/Space Science Institute
Download larger image version here

Cassini's investigation of the storm has also been aided by the
efforts of Earth-based amateur astronomers, who were able view
Saturn's dayside with their telescopes when Cassini could not. The
amateurs' images of Saturn provided the first visual confirmation of
the storm, now revealed in detail by the new views from Cassini


Personally I think the storm looks like an alien
 with floppy ears and it wouldn't suprise me if this doesn't get the
conspiracy theorists busy !!


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« Last Edit: 15/02/2006 19:18:27 by neilep »

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Pluto's new moons likely born with Charon
Posted: February 22, 2006

In a paper published today in Nature, a team of U.S. scientists led
by Dr. S. Alan Stern of Southwest Research Institute (SwRI),
concludes that two newly discovered small moons of Pluto were very
likely born in the same giant impact that gave birth to Pluto's much
larger moon, Charon. The team also argues that other, large binary
Kuiper Belt Objects (KBOs) may also frequently harbor small moons,
and that the small moons orbiting Pluto may generate debris rings
around Pluto.

This artist's rendering illustrates a giant impact
scenario similar to one that likely resulted in the two, newly
discovered moons of Pluto. Credit: Southwest Research Institute,
painting by Don Davis

(I'm so pleased that they mention it's an artists impression !!)

The team making these findings included Drs. Bill Merline, John
Spencer, Andrew Steffl, Eliot Young and Leslie Young of SwRI; Dr.
 Hal Weaver of the Johns Hopkins University Applied Physics
Laboratory; Max Mutchler of the Space Telescope Science Institute;
and Dr. Marc Buie of the Lowell Observatory. This team discovered
Pluto's two small moons in 2005 using sensitive images obtained by
the Hubble Space Telescope, as reported by Weaver et al. in an
accompanying paper in the February 23 issue of Nature.

"The evidence for the small satellites being born in the Charon-
forming collision is strong; it is based around the facts that the
small moons are in circular orbits in the same orbital plane as
Charon, and that they are also in, or very near, orbital resonance
with Charon," says lead author Stern, executive director of the SwRI
Space Science and Engineering Division.

Collisions, both large and small, are major processes that shaped
many aspects of our solar system. Scientists use computer
simulations to study the origin of planetary systems formed by
impact events of a scale much larger than could be simulated in a
laboratory. Another large collision, like the one thought to have
created Charon and Pluto's small moons, is believed responsible for
the formation of the Earth-moon pair.

"The idea that Pluto's small moons and Charon resulted from a giant
impact now seems compelling. Future simulations to determine the
characteristics of the impact required to produce all three
satellites should provide improved constraints on the early
dynamical history of the Kuiper Belt," adds Dr. Robin Canup,
director of SwRI's Space Studies Department, who in 2005 produced
the most comprehensive models to date of the Charon-forming impact.


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Offline neilep

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Rhea's wisps in colour
Posted: February 23, 2006

Credit: NASA/JPL/Space Science Institute
Download larger image version here, it's worth it...makes a nice desktop image

Bright, wispy markings stretch across a region of darker terrain on
Saturn's moon Rhea. In this extreme false-color view, the roughly
north-south fractures occur within strips of material (which appear
greenish here) that are a different color from the surrounding
cratered landscape.

To create the false-color view, ultraviolet, green and infrared
images were combined into a single black and white picture that
isolates and maps regional color differences. Most of the large-
scale variations in brightness across the surface are removed by
this process. This "color map" was then superimposed over a clear-
filter image.

The origin of the color differences is not yet understood, but it
may be caused by subtle differences in the surface composition or
grain sizes making up the icy soil.

Wispy markings were seen on the trailing hemispheres of both Rhea
and Dione in images taken by NASA's Voyager spacecraft, and were
hypothesized by some researchers to be the result of material
extruded onto the surface by ice volcanism. Cassini's earlier
revelation of the braided fractures on Dione led to speculation that
Rhea's wisps might also be created by fractures.

This view shows terrain on the trailing hemisphere of Rhea (1,528
kilometers, or 949 miles across). North is up.

The image was taken using the Cassini spacecraft narrow-angle camera
 at a distance of approximately 245,000 kilometers (152,000 miles)
from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 30
degrees. Image scale is 1 kilometer (4,771 feet) per pixel.


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« Last Edit: 27/02/2006 18:19:03 by neilep »

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Hubble's largest galaxy portrait showcases Pinwheel
Posted: February 28, 2006

This new Hubble image reveals the gigantic Pinwheel Galaxy, one of
the best known examples of "grand design spirals," and its
supergiant star-forming regions in unprecedented detail. The image
is the largest and most detailed photo of a spiral galaxy ever
released. Credit: European Space Agency & NASA

Download larger image version here

Giant galaxies weren't assembled in a day. Neither was this Hubble
Space Telescope image of the face-on spiral galaxy Messier 101 (the
Pinwheel Galaxy). The image is the largest and most detailed photo
 of a spiral galaxy ever released from Hubble. The galaxy's portrait
is actually composed from 51 individual Hubble exposures, in
addition to elements from images from ground-based photos. The final
 composite image measures a whopping 16,000 by 12,000 pixels.

The Hubble observations that went into assembling this image
 composite were retrieved from the Hubble archive and were
 originally acquired for a range of Hubble projects: determining the
expansion rate of the universe; studying the formation of star
clusters in giant starbirth regions; finding the stars responsible
for intense X-ray emission and discovering blue supergiant stars. As
an example of the many treasures hiding in this immense image, a
group led by K.D. Kuntz (Johns Hopkins University and NASA) recently
catalogued nearly 3000 previously undetected star clusters in it.

The giant spiral disk of stars, dust and gas is 170,000 light-years
across or nearly twice the diameter of our Milky Way. The galaxy is
estimated to contain at least one trillion stars. Approximately 100
billion of these stars alone might be like our Sun in terms of
temperature and lifetime. Hubble's high resolution reveals millions
of the galaxy's individual stars in this image.

Upper left: Background galaxies far behind the Pinwheel Galaxy. The
galaxies are clearly reddened by the dust in the Pinwheel. Upper
middle: Dust lanes in the Pinwheel galaxy. The dust particles
scatter blue light the most and therefore colour the light from
background stars red. The same effect is seen in sunsets on the
Earth. Upper right: A selection of some of the millions of
individual stars visible in Messier 101 with Hubble's sharp vision.
 In total it is estimated that the Pinwheel galaxy contains about
one trillion stars. Lower left: An example of some of the 3000
bright clusters of sizzling newborn blue stars in the Pinwheel
galaxy. Lower middle: Another "grand design" spiral lies behind the
Pinwheel Galaxy itself and is visible through its disk. Lower right:
 Two distant galaxies behind Messier 101 and a collection of
individual foreground stars from one of its spiral arms. Credit:
European Space Agency & NASA

Download larger image version here

The Pinwheel's spiral arms are sprinkled with large regions of star-
forming nebulae. These nebulae are areas of intense star formation within molecular hydrogen clouds. Brilliant young clusters of
sizzling newborn blue stars trace out the spiral arms. The disk of
the galaxy is so thin that Hubble easily sees many more distant
galaxies lying behind the foreground galaxy.

The Pinwheel Galaxy lies in the northern circumpolar constellation,
Ursa Major (The Great Bear) at a distance of 25 million light-years
from Earth. We are seeing the galaxy from Earth today as it was at
the beginning of Earth's Miocene Period when mammals flourished and
the Mastodon first appeared on Earth. The galaxy fills an area on
the sky of one-fifth the area of the full moon


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A frozen fountain near Paris' Luxembourg Park
AFP Thursday March 2, 01:54 PM

A frozen fountain near Paris' Luxembourg Park in January 2006. The
WWF environmental group warned that northern European countries will
be more exposed to severe winter storms unless power stations in
particular drastically cut greenhouse gas emissions. A frozen
fountain near Paris' Luxembourg Park in January 2006. The WWF
environmental group warned that northern European countries will be
more exposed to severe winter storms unless power stations in
particular drastically cut greenhouse gas emissions.


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A shocking surprise in Stephan's Quintet

Posted: March 3, 2006

Credit: NASA/JPL-Caltech/Max Planck Institute
Download larger image version here

This false-color composite image of the Stephan's Quintet galaxy
cluster clearly shows one of the largest shock waves ever seen
(green arc). The wave was produced by one galaxy falling toward
another at speeds of more than one million miles per hour. The image
is made up of data from NASA's Spitzer Space Telescope and a ground-
based telescope in Spain.

Four of the five galaxies in this picture are involved in a violent
collision, which has already stripped most of the hydrogen gas from
the interiors of the galaxies. The centers of the galaxies appear as
bright yellow-pink knots inside a blue haze of stars, and the galaxy
 producing all the turmoil, NGC7318b, is the left of two small
bright regions in the middle right of the image. One galaxy, the
large spiral at the bottom left of the image, is a foreground object
and is not associated with the cluster.

The titanic shock wave, larger than our own Milky Way galaxy, was
detected by the ground-based telescope using visible-light
wavelengths. It consists of hot hydrogen gas. As NGC7318b collides
with gas spread throughout the cluster, atoms of hydrogen are heated
in the shock wave, producing the green glow.

Stephan's Quintet is located 300 million light-years away in the
Pegasus constellation.


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Offline JimBob

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Nice happy face, Niel.

Offline neilep

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Originally posted by JimBob

Nice happy face, Niel.

Here's another happy face , just for you Jim !! :D

Japanese researchers extract vanilla from cow dung

A milk cow eats grain at a farm. Japanese researchers
have succeeded in making the sweet smell of vanilla come out of the
last thing people could imagine -- cow dung

In a world-first recycling project, a one-hour heating and
pressuring process allows cow feces to produce vanillin, the main
component of the vanilla-bean extract, according to researcher Mayu

The vanillin extracted from the feces could be used in products such
as shampoo and aromatic candles but not in food, said Yamamoto, who
works for the Research Institute of the state-run International
Medical Center of Japan.

Compared with usual vanilla, "this component is exactly the same but
it would be difficult for people to accept it in food, given the
recent rules of disclosing the origins of ingredients," she said.

The production cost using dung is less than a half of making
vanillin out of vanilla beans, she added.

The feces of grass-eating animals is abundant with lignin, the
chemical compound that exists in plants and trees and is used to
produce vanilla aroma, Yamamoto said.

"Lignin is difficult to decompose," she said. "Farmers are troubled
by how to dispose properly of animal excrement. We tried to solve
this from a recycling viewpoint," she said.

After taking the vanillin, the processed feces could be returned to
the soil, she said.

The research has been done in cooperation with major Japanese
chemicals firm Sekisui Chemical.

The research team aims to develop a machine to handle several tons
of feces a day and put it in practical use in two-to-three years.

SOURCE: AFP vIA yahoonews

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« Last Edit: 07/03/2006 20:57:52 by neilep »

Offline JimBob

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She is cute. Is she married?  [8D]

Offline neilep

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Originally posted by JimBob


She is cute. Is she married?  [8D]

I think she is Jim, but I believe there are udder cuties available !!:D

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Impact of Climate Warming on Polar Ice Sheets Confirmed03.08.06

In the most comprehensive survey ever undertaken of the massive ice
sheets covering both Greenland and Antarctica, NASA scientists
confirm climate warming is changing how much water remains locked in
Earth's largest storehouse of ice and snow.

Antarctica lost much more ice to the sea than it
gained from snowfall, resulting in an increase in sea level.
Antarctica lost much more ice to the sea than it gained from
snowfall, resulting in an increase in sea level. Credit: NASA/SVS

Other recent studies have shown increasing losses of ice in parts of
these sheets. This new survey is the first to inventory the losses
of ice and the addition of new snow on both in a consistent and
comprehensive way throughout an entire decade.

The survey shows that there was a net loss of ice from the combined
polar ice sheets between 1992 and 2002 and a corresponding rise in
sea level. The survey documents for the first time extensive
thinning of the West Antarctic ice shelves and an increase in
snowfall in the interior of Greenland, as well as thinning at the
edges. All are signs of a warming climate predicted by computer

The survey, published in the Journal of Glaciology, combines new
satellite mapping of the height of the ice sheets from two European
Space Agency satellites. It also used previous NASA airborne mapping
 of the edges of the Greenland ice sheets to determine how fast the
thickness is changing.

The Greenland ice sheet gained more ice from snowfall at high
altitudes than it lost from melting ice along its coast. The
Greenland ice sheet gained more ice from snowfall at high altitudes
than it lost from melting ice along its coast. Credit: NASA/SVS

In Greenland, the survey saw large ice losses along the southeastern
 coast and a large increase in ice thickness at higher elevations in
the interior due to relatively high rates of snowfall. This study
suggests there was a slight gain in the total mass of frozen water
in the ice sheet over the decade studied, contrary to previous

This situation may have changed in just the past few years,
according to lead author Jay Zwally of NASA's Goddard Space Flight
Center, Greenbelt, Md. Last month NASA scientists at the Jet
Propulsion Laboratory, Pasadena, Calif., reported a speed up of ice
flow into the sea from several Greenland glaciers. That study
included observations through 2005; Zwally's survey concluded with
2002 data.

When the scientists added up the overall gains and losses of ice
from the Greenland and Antarctic ice sheets, there was a net loss of
ice to the sea. The amount of water added to the oceans (20 billion
tons) is equivalent to the total amount of freshwater used in homes,
businesses and farming in New York, New Jersey and Virginia each year.

"The study indicates that the contribution of the ice sheets to
recent sea-level rise during the decade studied was much smaller
than expected, just two percent of the recent increase of nearly
three millimeters a year," says Zwally. "Continuing research using
NASA satellites and other data will narrow the uncertainties in this
important issue."

NASA is continuing to monitor the polar ice sheets with the Ice,
 Cloud and land Elevation Satellite (ICESat), launched in January
2003. ICESat uses a laser beam to measure the elevation of ice
sheets with unprecedented accuracy three times a year. The first
comprehensive ice sheet survey conducted by ICESat is expected early
next year, said Zwally, who is the mission's project scientist.


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Double helix nebula found in center of the Milky Way
Posted: March 15, 2006

Astronomers report an unprecedented elongated double helix nebula
near the center of our Milky Way galaxy, using observations from
NASA's Spitzer Space Telescope. The part of the nebula the
astronomers observed stretches 80 light years in length. The
research is published March 16 in the journal Nature

The double helix nebula. The spots are infrared-luminous
 stars, mostly red giants and red supergiants. Many other stars are
present in this region, but are too dim to appear even in this
sensitive infrared image. Credit: NASA/JPL-Caltech/UCLA

"We see two intertwining strands wrapped around each other as in a
DNA molecule," said Mark Morris, a UCLA professor of physics and
astronomy, and lead author. "Nobody has ever seen anything like that
before in the cosmic realm. Most nebulae are either spiral galaxies
full of stars or formless amorphous conglomerations of dust and gas -
 space weather. What we see indicates a high degree of order."

The double helix nebula is approximately 300 light years from the
enormous black hole at the center of the Milky Way. (The Earth is
more than 25,000 light years from the black hole at the galactic

The Spitzer Space Telescope, an infrared telescope, is imaging the
sky at unprecedented sensitivity and resolution; Spitzer's
sensitivity and spatial resolution were required to see the double
helix nebula clearly.

"We know the galactic center has a strong magnetic field that is
highly ordered and that the magnetic field lines are oriented
perpendicular to the plane of the galaxy," Morris said. "If you take
these magnetic field lines and twist them at their base, that sends
what is called a torsional wave up the magnetic field lines.

"You can regard these magnetic field lines as akin to a taut rubber
band," Morris added. "If you twist one end, the twist will travel up
the rubber band."

Offering another analogy, he said the wave is like what you see if
you take a long loose rope attached at its far end, throw a loop,
and watch the loop travel down the rope.

"That's what is being sent down the magnetic field lines of our
galaxy," Morris said. "We see this twisting torsional wave
propagating out. We don't see it move because it takes 100,000 years
to move from where we think it was launched to where we now see it,
 but it's moving fast - about 1,000 kilometers per second - because
the magnetic field is so strong at the galactic center - about 1,000
times stronger than where we are in the galaxy's suburbs."

A strong, large-scale magnetic field can affect the galactic orbits
of molecular clouds by exerting a drag on them. It can inhibit star
formation, and can guide a wind of cosmic rays away from the central
 region; understanding this strong magnetic field is important for
understanding quasars and violent phenomena in a galactic nucleus.
Morris will continue to probe the magnetic field at the galactic
center in future research.

This magnetic field is strong enough to cause activity that does not
occur elsewhere in the galaxy; the magnetic energy near the galactic
center is capable of altering the activity of our galactic nucleus
and by analogy the nuclei of many galaxies, including quasars, which
are among the most luminous objects in the universe. All galaxies
that have a well-concentrated galactic center may also have a strong
magnetic field at their center, Morris said, but so far, ours is the
only galaxy where the view is good enough to study it.

Morris has argued for many years that the magnetic field at the
galactic center is extremely strong; the research published in
Nature strongly supports that view.

The magnetic field at the galactic center, though 1,000 times weaker
than the magnetic field on the sun, occupies such a large volume
that it has vastly more energy than the magnetic field on the sun.
It has the energy equivalent of 1,000 supernovae.

What launches the wave, twisting the magnetic field lines near the
center of the Milky Way? Morris thinks the answer is not the
monstrous black hole at the galactic center, at least not directly.

Orbiting the black hole like the rings of Saturn, several light
years away, is a massive disk of gas called the circumnuclear disk;
 Morris hypothesizes that the magnetic field lines are anchored in
this disk. The disk orbits the black hole approximately once every
10,000 years.

"Once every 10,000 years is exactly what we need to explain the
twisting of the magnetic field lines that we see in the double helix
nebula," Morris said.


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« Last Edit: 16/03/2006 18:46:25 by neilep »

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Huge crowds extend Darwin exhibit in New York

A variety of skulls are on display as part of an
exhibition on Charles Darwin at the American Museum of Natural History in
New York. The exhibition has been extended by five months amid an
overwhelming public response to what was touted as a scholarly rebuke to
opponents of teaching evolution in US schools

NEW YORK (AFP) - A monumental Charles Darwin exhibition in New York has been extended by five months amid an overwhelming public response to what was touted as a scholarly rebuke to opponents of teaching evolution in US schools.

The American Museum of Natural History said Wednesday that nearly 200,000 people had visited "Darwin" since it opened three months ago.

Originally slated to close at the end of this month, the exhibition will now run through August 20, said museum spokesman Joshua Schnakenberg.

"Darwin" had opened amid furious debate in many school districts over the teaching of the 19th century naturalist's evolutionary theory and the first trial on the teaching of the God-centered alternative favoured by many religious groups, "intelligent design," or ID.

That trial, in Pennsylvania, ended in defeat for the evangelical right with the judge in the case decrying the "breathtaking inanity" of the school board in the town of Dover which backed the concept that nature is so complex it must be the work of a superior being.

"Our conclusion today is that it is unconstitutional to teach ID as an alternative to evolution in a public school science classroom," the judge said in his ruling in December.

An early section of the New York exhibit is devoted to the question, "What is a Theory?" and seeks to clarify the distinction between scientific theories and non-scientific explanations about the origins and diversity of life.

"This is really for the schoolchildren of America. This is the evidence of evolution," said the exhibit's curator, Niles Eldridge.

In a Gallup poll released last October, 53 percent of American adults agreed with the statement that God created humans in their present form exactly the way the Bible describes it.

Thirty-one percent stood by the "intelligent design" stance, while only 12 percent said humans have evolved from other forms of life and "God has no part."


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Great galactic buddies

Astronomers using NASA's Spitzer Space Telescope have conducted a cosmic safari to seek out a rare galactic species. Their specimens -- clusters of galaxies in the very distant universe -- are few and far between, and have hardly ever been detected beyond a distance of 7 billion light-years from Earth.

In this false-color composite, some of the oldest
galaxy clusters in the universe pose for Spitzer's infrared array
camera. The individual galaxies that make up the distant clusters
are shown as red dots in all four images. The green blobs are Milky
Way stars along the line of sight, and the blue specks are faint
galaxies at various distances along the line of sight. The green and
blue data are from a visible-light, ground-based telescope. Credit:
NASA/JPL-Caltech/UCDavis/Lawrence Livermore National Laboratory

Download larger image versionhere

To find the clusters, the team carefully sifted through Spitzer infrared pictures and ground-based catalogues; estimated rough distances based on the cluster galaxies' colors; and verified suspicions using a spectrograph instrument at the W.M. Keck Observatory in Hawaii.

Ultimately, the expedition resulted in quite a galactic catch -- the most distant galaxy cluster ever seen, located 9 billion light-years away. This means the cluster lived in an era when the universe was a mere 4.5 billion years old. The universe is believed to be 13.7 billion years old.

"Detecting a galaxy cluster 9 billion light-years away is very exciting," said the study's lead investigator, Dr. Peter Eisenhardt of NASA's Jet Propulsion Laboratory. "It's really amazing that Spitzer's 85-centimeter telescope can see 9 billion years back in time."

Using the same methods, the astronomers also found three other clusters living between 7 and 9 billion light-years away.

"Spitzer is an excellent instrument for detecting very distant galaxy clusters because they stand out so brightly in the infrared," said co-investigator Dr. Mark Brodwin, also of JPL. "You can think of these distant galaxy cluster surveys as a game of 'Where's Waldo?' With an optical telescope you can spot 'Waldo,' or the distant galaxy clusters, by carefully searching for them amongst a sea of faint galaxies."

"But in the Spitzer data, it's as though Waldo is wearing a bright neon hat and can be easily picked out of the crowd," Brodwin added.

Galaxy clusters are the largest gravitationally bound structures in the universe. A typical cluster can contain thousands of galaxies and trillions of stars. Because of their huge size and mass, they are relatively rare. For example, if Earth were to represent the entire universe, then countries would be the equivalent of galaxies, and continents would be the galaxy clusters.

Galaxy clusters grow like snowballs, picking up new galaxies from gravitational interactions over billions of years. For this reason, team members say these behemoths should be even rarer in the very distant universe.

"The ultimate goal of this research is to find out when the galaxies in this and other distant clusters formed," said co-investigator Dr. Adam Stanford, of the University of California at Davis. Stanford is the lead author of a paper on the most distant galaxy cluster's discovery, which was published in the December 2005 issue of Astrophysical Journal Letters.

This is the second time Eisenhardt and Stanford have broken the record for capturing the most distant galaxy cluster. Both say they accidentally broke the record in 1997 when they detected a cluster located 8.7 billion light-years away. The discovery was made by a deep survey of a 0.03-degree patch of sky, or an area significantly smaller than a pea held out at arms length, for 30 nights at the Kitt Peak National Observatory in Arizona.

"We were lucky in 1997 because we weren't looking for galaxy clusters and found the most distant one ever detected in a very small patch of sky," said Stanford. "Because galaxy clusters are so massive and rare, you typically need to deeply survey a large area of sky to find them."

"With Spitzer's great infrared sensitivity we surveyed more deeply in 90 seconds than we could in hours of exposure in the 1997 observations, and we used this advantage to survey a region 300 times larger," adds Eisenhardt.

The 9 billion-year-old cluster is just one of 25 the team captured on their Spitzer safari. They are currently preparing for more observations this spring at the W.M. Keck Observatory to confirm the distance of additional galaxy clusters from their sample. According to Eisenhardt, some of the clusters awaiting confirmation may be even more distant than the current record holder.


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Cannibal stars like their food hot, XMM-Newton reveals
Posted: March 26, 2006

The European Space Agency's XMM-Newton observatory has seen vast clouds of superheated gas, whirling around miniature stars and escaping from being devoured by the stars' enormous gravitational fields - giving a new insight into the eating habits of the galaxy's "cannibal" stars.

Artist's impression of a vast cloud of superheated gas
 whirling around an asteroid-sized cannibal star, part of a low-mass
 X-ray binary star system. Credit: ESA


The clouds of gas range in size from a few hundred thousand kilometres to a few million kilometres, ten to one hundred times larger than the Earth. They are composed of iron vapour and other chemicals at temperatures of many millions of degrees.

"This gas is extremely hot, much hotter than the outer atmosphere of the Sun," said Maria Diaz Trigo of ESA's European Science and Technology Research Centre (ESTEC), who led the research.

ESA's XMM-Newton x-ray observatory made the discovery when it observed six so-called 'low-mass X-ray binary' stars (LMXBs). The LMXBs are pairs of stars in which one is the tiny core of a dead star.

Measuring just 15-20 kilometres across and comparable in size to an asteroid, each dead star is a tightly packed mass of neutrons containing more than 1.4 times the mass of the Sun.

Its extreme density generates a powerful gravitational field that rips gas from its 'living' companion star. The gas spirals around the neutron star, forming a disc, before being sucked down and crushed onto its surface, a process known as 'accretion'.

The newly discovered clouds sit where the river of matter from the companion star strikes the disc. The extreme temperatures have ripped almost all of the electrons from the iron atoms, leaving them carrying extreme electrical charges. This process is known as 'ionisation'.

The discovery solves a puzzle that has dogged astronomers for several decades. Certain LMXBs appear to blink on and off at X-ray wavelengths. These are 'edge-on' systems, in which the orbit of each gaseous disc lines up with Earth.

In previous attempts to simulate the blinking, clouds of low-temperature gas were postulated to be orbiting the neutron star, periodically blocking the X-rays. However, these models never reproduced the observed behaviour well enough.

XMM-Newton solves this by revealing the ionised iron. "It means that these clouds are much hotter than we anticipated," said Diaz. With high-temperature clouds, the computer models now simulate much better the dipping behaviour.

Some 100 known LMXBs populate our galaxy, the Milky Way. Each one is a stellar furnace, pumping X-rays into space. They represent a small-scale model of the accretion thought to be taking place in the very heart of some galaxies. One in every ten galaxies shows some kind of intense activity at its centre.

This activity is thought to be coming from a gigantic black hole, pulling stars to pieces and devouring their remains. Being much closer to Earth, the LMXBs are easier to study than the active galaxies.

"Accretion processes are still not well understood. The more we understand about the LMXBs, the more useful they will be as analogues to help us understand the active galactic nuclei," says Diaz.


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Images from Venus Give Clues About Planet's Climate

This image from Thursday shows a composite view of Venus' south pole

Scientists in Europe have released their first photos of Venus'
southern pole sent from the Venus Express spacecraft. They show
dense, swirling clouds similar to formations found at the planet's
northern pole.

The images are the first pictures ever taken of the neighboring
planet's southern pole and provide researchers with new data about
Venus' largely unknown atmosphere. The spacecraft's monitoring
camera will take photographs over the next few months with aim of
getting a more comprehensive picture of cloud formations and climate


"We can see there is a twister here that is similar to that which we
know from the northern pole," said Horst Uwe Keller, leader of the
 team operating the craft's wide-angle, multichannel camera.

The clouds are 13 miles deep and completely enclose Venus. With
infrared technology that enables the camera to peer though the
clouds, scientists hope to determine how the sulphuric acid around
the planet was formed, and find the cause of the high winds that
send it billowing in massive clouds.

Shared characteristics with Earth?

Venus Express is studying the cloud system in the planet's violent atmosphere

Researchers want to learn when and why the planet's extreme
atmosphere developed the way it did, featuring temperatures reaching
 up to 500 degrees Celsius and hurricane-like storms. They also want
 to find out if Venus ever had an atmosphere or other features more
similar to Earth's.


"There's also the question of how large the zone in the universe is
 where life can develop," said Keller.


Europe's first space probe to Venus slipped smoothly into orbit on
Tuesday. In the next several weeks, scientists will run more
thorough tests on the spacecraft's instruments and by June, all
instruments should be fully functioning.


In the coming months, the Venus Express will tighten its orbit
around the planet, providing scientists more detailed and revealing
images of the planet from a distance of about 155 miles (250

A picture released Thursday shows clouds at the south pole


Other sauces are Banana & Toffee sauce ...yummy !!


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Crescent Titan with rings
Posted: April 15, 2006

Credit: NASA/JPL/Space Science Institute
Download larger image version here

This poetic scene shows the giant, smog-enshrouded moon Titan behind
 Saturn's nearly edge-on rings. Much smaller Epimetheus (116
kilometers, or 72 miles across) is just visible to the left of Titan
(5,150 kilometers, or 3,200 miles across).

The image was taken in visible light with the Cassini spacecraft
narrow-angle camera at a distance of approximately 4.1 million
kilometers (2.5 million miles) from Titan. The image scale is 25
kilometers (16 miles) per pixel on Titan. The brightness of
Epimetheus was enhanced for visibility.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. The Jet
Propulsion Laboratory, a division of the California Institute of
Technology in Pasadena, manages the mission for NASA's Science
Mission Directorate, Washington, D.C. The Cassini orbiter and its
two onboard cameras were designed, developed and assembled at JPL.
 The imaging operations center is based at the Space Science
Institute in Boulder, Colo


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Hubble spies gemstones in the southern sky
Posted: April 18, 2006

<font color="blue"><b>Image credit: European Space Agency & NASA
Download larger image version </font id="blue"> here</b>
The Hubble Space Telescope has captured the most detailed images to
 date of the open star clusters NGC 265 and NGC 290 in the Small
Magellanic Cloud -- two sparkling sets of gemstones in the southern

These images, taken with Hubble's Advanced Camera for Surveys, show
a myriad of stars in crystal clear detail. The brilliant open star
clusters are located about 200,000 light-years away and are roughly
65 light-years across.

Star clusters can be held together tightly by gravity, as is the
case with densely packed crowds of hundreds of thousands of stars,
 called globular clusters. Or, they can be more loosely bound,
irregularly shaped groupings of up to several thousands of stars,
 like the open clusters shown in this image.

The stars in these open clusters are all relatively young and were
born from the same cloud of interstellar gas. Just as old school-
friends drift apart after graduation, the stars in an open cluster
will only remain together for a limited time and gradually disperse
into space, pulled away by the gravitational tugs of other passing
clusters and clouds of gas. Most open clusters dissolve within a few
hundred million years, whereas the more tightly bound globular
clusters can exist for many billions of years.

Open star clusters make excellent astronomical laboratories. The
stars may have different masses, but all are at about the same
distance, move in the same general direction, and have approximately
the same age and chemical composition. They can be studied and
compared to find out more about stellar evolution, the ages of such
clusters, and much more.

The Small Magellanic Cloud, which hosts the two star clusters, is
one of the small satellite galaxies of the Milky Way. It can be seen
with the unaided eye as a hazy patch in the constellation Tucana
(the Toucan) in the Southern Hemisphere. The Small Magellanic Cloud
is rich in gas nebulae and star clusters. It is most likely that
this irregular galaxy has been disrupted through repeated
interactions with the Milky Way, resulting in the vigorous star-
forming activity seen throughout the cloud. NGC 265 and NGC 290 may
very well owe their existence to these close encounters with the
Milky Way.

The images were taken in October and November 2004 through F435W,
F555W, and F814W filters (shown in blue, green, and red,

The Hubble Space Telescope is a project of international cooperation
between NASA and the European Space Agency. The Space Telescope
Science Institute in Baltimore conducts Hubble science operations.
The Institute is operated for NASA by the Association of
Universities for Research in Astronomy, Inc., Washington.


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well mr hubble aint so clever,he missed out m3227895beta a small binary star to the right of ngc285,  naaah im talking tosh,ace piccy tho [8D]

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XMM-Newton observes fossil galaxy cluster

XMM-Newton observations of the fossil
galaxy cluster RX J1416.5+2315, show a cloud of hot gas emitting X-rays (in
blue). The cloud, reaching temperatures of about 50 million degrees, extend
over 3.5 million light years and surround a giant elliptical galaxy believed to
have grown to its present size by cannibalising its neighbours.

Credit: Credits: Khosroshahi, Maughan,
Ponman, Jones, ESA, ING

Taking advantage of the high sensitivity of ESA's XMM-Newton and the sharp vision of NASA's Chandra X-Ray space observatories, astronomers have studied the behaviour of massive fossil galaxy clusters, trying to find out how they find the time to form…
Many galaxies reside in galaxy groups, where they experience close encounters with their neighbours and interact gravitationally with the dark matter - mass which permeates the whole intergalactic space but is not directly visible because it doesn't emit radiation. These interactions cause large galaxies to spiral slowly towards the centre of the group, where they can merge to form a single giant central galaxy, which progressively swallows all its neighbours.

If this process runs to completion, and no new galaxies fall into the group, then the result is an object dubbed a 'fossil group', in which almost all the stars are collected into a single giant galaxy, which sits at the centre of a group-sized dark matter halo. The presence of this halo can be inferred from the presence of extensive hot gas, which fills the gravitational potential wells of many groups and emits X-rays.

A group of international astronomers studied in detail the physical features of the most massive and hot known fossil group, with the main aim to solve a puzzle and understand the formation of massive fossils. In fact, according to simple theoretical models, they simply could not have formed in the time available to them!

The fossil group investigated, called 'RX J1416.4+2315', is dominated by a single elliptical galaxy located one and a half thousand million light years away from us, and it is 500 thousand million times more luminous than the Sun.

The XMM-Newton and Chandra X-ray observations, combined with optical and infrared analyses, revealed that group sits within a hot gas halo extending over three million light years and heated to a temperature of 50 million degrees, mainly due to shock heating as a result of gravitational collapse.

Such a high temperature, about as twice as the previously estimated values, is usually characteristic of galaxy clusters. Another interesting feature of the whole cluster system is its large mass, reaching over 300 trillion solar masses. Only about two percent of it in the form of stars in galaxies, and 15 percent in the form of hot gas emitting X-rays. The major contributor to the mass of the system is the invisible dark matter, which gravitationally binds the other components.

According to calculations, a fossil cluster as massive as RX J1416.4+2315 would have not had the time to form during the whole age of the universe. The key process in the formation of such fossil groups is the process known as 'dynamical friction', whereby a large galaxy loses its orbital energy to the surrounding dark matter. This process is less effective when galaxies are moving more quickly, which they do in massive 'clusters' of galaxies.

This, in principle, sets an upper limit to the size and mass of fossil groups. The exact limits are, however, still unknown since the geometry and mass distribution of groups may differ from that assumed in simple theoretical models.

"Simple models to describe the dynamical friction assume that the merging galaxies move along circular orbits around the centre of the cluster mass", says Habib Khosroshahi from the University of Birmingham (UK), first author of the results. "Instead, if we assume that galaxies fall towards the centre of the developing cluster in an asymmetric way, such as along a filament, the dynamic friction and so the cluster formation process may occur in a shorter time scale," he continues. Such a hypothesis is supported by the highly elongated X-ray emission we observed in RX J1416.4+2315, to sustain the idea of a collapse along a dominant filament."

The optical brightness of the central dominant galaxy in this fossil is similar to that of brightest galaxies in large clusters (called 'BCGs'). According to the astronomers, this implies that such galaxies could have originated in fossil groups around which the cluster builds up later. This offers an alternative mechanism for the formation of BCGs compared to the existing scenarios in which BCGs form within clusters during or after the cluster collapse.

"The study of massive fossil groups such as RX J1416.4+2315 is important to test our understanding of the formation of structure in the universe," adds Khosroshahi. "Cosmological simulations are underway which attempt to reproduce the properties we observe, in order to understand how these extreme systems develop," he concludes.


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Evolutionary Back Story: Thoroughly modern spine supported human ancestor
Bruce Bower

Bones from a spinal column discovered at a nearly 1.8-million-year-old site in central Asia support the controversial possibility that ancient human ancestors spoke to one another.

WIDE OPEN. A recently discovered Homo erectus vertebra
from central Asia (left) displays a larger spinal cord canal than does
 a corresponding bone (right) from a skeleton that had been found in


Excavations in 2005 at Dmanisi, Georgia, yielded five vertebrae from a Homo erectus individual, says anthropologist Marc R. Meyer of the University of Pennsylvania in Philadelphia. The finds occurred in previously dated sediment that has yielded several skulls now attributed to H. erectusThe new discoveries represent the oldest known vertebrae for the genus Homo, Meyer announced last week at the annual meeting of the Paleoanthropology Society in San Juan, Puerto Rico. The fossils consist of one lumbar, two thoracic, and two cervical vertebrae.

Meyer and his colleagues—David Lordkipanidze and Abesalom Vekua, both of the Georgian State Museum in Tbilisi—compared the size, shape, and volume of the Dmanisi vertebrae with more than 2,200 corresponding bones from people, chimpanzees, and gorillas.

"The Dmanisi spinal column falls within the human range and would have comfortably accommodated a modern human spinal cord," Meyer says.

Moreover, the fossil vertebrae would have provided ample structural support for the respiratory muscles needed to articulate words, he asserts. Although it's impossible to confirm that our prehistoric ancestors talked, Meyer notes, H. erectus at Dmanisi faced no respiratory limitations on speech.

In contrast, the 1984 discovery in Kenya of a boy's 1.6-million-year-old skeleton, identified by some researchers as H. erectus and by others as Homo ergaster, yielded small, chimplike vertebrae. Researchers initially suspected that the ancient youth and his presumably small-spined comrades lacked the respiratory control to talk as people do today.

In the past 5 years, investigators including Bruce Latimer of the Cleveland Museum of Natural History have suggested that the prehistoric boy offers a misleading view of H. erectus' backbone. They contend that growth of the bony canal encasing his spinal cord had been stunted, and spinal cord compression would have impeded his movement and caused limb weakness.

Finding ancient, humanlike vertebrae at Dmanisi fits with Latimer's view, Meyer says. Infant malnutrition, which often arrests growth of the human vertebral canal, may have affected the H. erectus youth, Meyer suggests.

The ancient boy, who died at age 10 or so, would have required intensive protection and provisioning, Meyer asserts. "Both altruism and spoken language may have been part of the behavioral repertoire of early Homo," the Pennsylvania researcher says.

The modern-looking vertebrae at Dmanisi, remarks David Frayer of the University of Kansas in Lawrence, comport with earlier fossil-skull studies indicating that early Homo possessed a speech-ready vocal tract.

Robert C. McCarthy of Florida Atlantic University in Boca Raton disagrees. At the Paleoanthropology Society meeting, he presented vocal-tract reconstructions for various ancient Homo species suggesting that the capacity to articulate speech as well as people do now emerged exclusively in Homo sapiens around 50,000 years ago.

Before then, all members of the Homo genus—including H. sapiens—possessed a short set of neck vertebrae, resulting in a vocal tract with a restricted range of speech sounds, McCarthy and his coworkers argue.

Many populations today, including Australian aborigines, possess neck vertebrae comparable in length to those that McCarthy's team considered inadequate for modern speech, Meyer responds.


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The record of Rhea
Posted: May 14, 2006

Credit: NASA/JPL/Space Science Institute
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Cassini looks down upon Rhea, whose cratered surface was already ancient before any complex life developed on Earth. The terrain seen here has probably changed little in the past billion years.

This view shows terrain on the Saturn-facing hemisphere of Rhea (1,528 kilometers, or 949 miles across). North is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera at a distance of approximately 94,000 kilometers (59,000 miles) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 109 degrees. Image scale is 558 meters (1,832 feet) per pixel.


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Dwarfs gave way to giants
Posted: May 17, 2006

The first galaxies were small - about 10,000 times less massive than the Milky
 Way. Billions of years ago, those mini-furnaces forged a multitude of hot,
massive stars. In the process, they sowed the seeds for their own
destruction by bathing the universe in ultraviolet radiation. According to
theory, that radiation shut off further dwarf galaxy formation by both ionizing
 and heating surrounding hydrogen gas. Now, astronomers Stuart Wyithe
(University of Melbourne) and Avi Loeb (Harvard-Smithsonian Center for
Astrophysics) are presenting direct evidence in support of this theory.

This artist's conception shows a collection of hot, blue stars
comprising an early dwarf galaxy surrounded by red hydrogen gas. Credit:
David A. Aguilar (CfA)

Wyithe and Loeb showed that fewer, larger galaxies, rather than more
numerous, smaller galaxies, dominated the billion-year-old universe. Dwarf
galaxy formation essentially shut off only a few hundred million years after the
 Big Bang.

"The first dwarf galaxies sabotaged their own growth and that of their
siblings," says Loeb. "This was theoretically expected, but we identified the
first observational evidence for the self-destructive behavior of early

Their research is being reported in the May 18, 2006 issue of Nature.

Nearly 14 billion years ago, the Big Bang filled the universe with hot matter in
the form of electrons and hydrogen and helium ions. As space expanded and
cooled, electrons and ions combined to form neutral atoms. Those atoms
efficiently absorbed light, yielding a pervasive dark fog throughout space.
Astronomers have dubbed this era the "Dark Ages."

The first generation of stars began clearing that fog by bathing the universe
in ultraviolet radiation. UV radiation splits atoms into negatively charged
electrons and positively charged ions in a process called ionization. Since the
 Big Bang created an ionized universe that later became neutral, this second
phase of ionization by stars is known as the "epoch of reionization." It took
place in the first few hundred million years of existence.

"We want to study this time period because that's when the primordial soup
evolved into the rich zoo of objects we now see," said Loeb.

During this key epoch in the history of the universe, gas was not only ionized
, but also heated. While cool gas easily clumps together to form stars and
galaxies, hot gas refuses to be constrained. The hotter the gas, the more
massive a galactic "seed" must be to attract enough matter to become a

Before the epoch of reionization, galaxies containing only 100 million solar
masses of material could form easily. After the epoch of reionization, galaxies
required more than 10 billion solar masses of material to be assembled.

To determine typical galaxy masses, Wyithe and Loeb looked at light from
quasars - powerful light sources visible across vast distances. The light from
 the farthest known quasars left them nearly 13 billion years ago, when the
universe was a fraction of its present age. Quasar light is absorbed by
intervening clouds of hydrogen associated with early galaxies, leaving telltale
 bumps and wiggles in the quasar's spectrum.

By comparing the spectra of different quasars along different lines of sight,
Wyithe and Loeb determined typical galaxy sizes in the infant universe. The
presence of fewer, larger galaxies leads to more variation in the absorption
seen along various lines of sight. Statistically, large variation is exactly what
 Wyithe and Loeb found.

"As an analogy, suppose you are in a room where everybody is talking,"
explains Wyithe. "If this room is sparsely populated, then the background
noise is louder in some parts of the room than others. However if the room is
 crowded, then the background noise is the same everywhere. The fact that
we see fluctuations in the light from quasars implies that the early universe
was more like the sparse room than the crowded room."

Astronomers hope to confirm the suppression of dwarf galaxy formation using
the next generation of telescopes - both radio telescopes that can detect
distant hydrogen and infrared telescopes that can directly image young
galaxies. Within the next decade, researchers using these new instruments
will illuminate the "Dark Ages" of the universe.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for
Astrophysics (CfA) is a joint collaboration between the Smithsonian
Astrophysical Observatory and the Harvard College Observatory. CfA
scientists, organized into six research divisions, study the origin, evolution
and ultimate fate of the universe.


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Hubble captures a 'five-star' rated gravitational lens
Posted: May 22, 2006

The Hubble Space Telescope has captured the first-ever picture of a distant quasar lensed into five images. In addition, the image holds a treasure of lensed galaxies and even a supernova.

Credit: ESA, NASA, K. Sharon (Tel Aviv University) and E. Ofek (Caltech)
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The most unique feature in a new image taken with the NASA/ESA Hubble Space Telescope is a group of five quasar images produced by a process called gravitational lensing, in which the gravitational field of a massive object - in this case, a cluster of galaxies - bends and amplifies light from an object - in this case, a quasar - farther behind it.

Although other multiply lensed quasars have been seen before this newly observed ³quintuple quasar² is the only case so far in which multiple quasar images are produced by an entire galaxy cluster acting as a gravitational lens.

The background quasar is the brilliant core of a galaxy. It is powered by a black hole, which is devouring gas and dust and creating a gusher of light in the process. When the quasar's light passes through the gravity field of the galaxy cluster that lies between us and the quasar, the light is bent by the space-warping gravity field in such a way that five separate images of the object are produced surrounding the cluster's centre. The fifth quasar image is embedded to the right of the core of the central galaxy in the cluster. The cluster also creates a cobweb of images of other distant galaxies gravitationally lensed into arcs.

The galaxy cluster creating the lens is known as SDSS J1004+4112 and was discovered as part of the Sloan Digital Sky Survey. It is one of the more distant clusters known (seven billion light-years, redshift z=0.68), and is seen when the Universe was half its present age.

Gravitational lensing occurs for extremely concentrated masses like the cores of galaxies or galaxy clusters. Their strong gravity warps the surrounding space, and light travelling through that warped space bends its direction. Multiple images of a distant light source may be seen, each taking a different path through the warped space.

Credit: ESA, NASA, K. Sharon (Tel Aviv University) and E. Ofek (Caltech)
A gravitational lens will always produce an odd number of lensed images, but one image is usually very weak and embedded deep within the light of the lensing object itself. Though previous observations of SDSS J1004+4112 have revealed four of the images of this system, Hubble's sharp vision and the high magnification of this gravitational lens combine to place a fifth image far enough from the core of the central imaging galaxy to make it visible as well.

The galaxy hosting the background quasar is at a distance of 10 billion light years (at redshift 1.74). The quasar host galaxy can be seen in the image as faint red arcs. This is the most highly magnified quasar host galaxy ever seen.

The Hubble picture also shows a large number of stretched arcs that are more distant galaxies lying behind the cluster, each of which is split into multiple distorted images. The most distant galaxy identified and confirmed so far is 12 billion light years away (a redshift of 3.33, corresponding to only 1.8 billion years after the Big Bang).

By comparing this image to a picture of the cluster obtained with Hubble a year earlier, the researchers discovered a rare event - a supernova exploding in one of the cluster galaxies. This supernova exploded seven billion years ago, and the data, together with other supernova observations, are being used to try to reconstruct how the Universe was enriched by heavy elements through these explosions.


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