Astronomical News

[Anonymous]

This time it looks like they are just talking about the thin outer reaches of the Andromeda galaxy; they seem to think that the disk extends further into interstellar space that they thought previously.
If it does, then the same might be true of our own galaxy- and some, or all of the others.

Incidentally, when you see the Andromeda galaxy up there in the sky with the naked eye, what you are seeing is just the central hub, the brightest part. The greatest part of the galaxy, including most of the spiral arms, is too dim to see without instruments; the full glory of our sister galaxy is best revealed in photographs of various kinds.

 

[OneWingedBird]

Ah, thanks for the explanation

 

[Rubyait]

i thought this was pretty cool

Biggest ever cosmos simulation

Astronomers have used supercomputers to re-create how the Universe evolved into the shape it is today.
The simulation by an international team is the biggest ever attempted and shows how structures in the Universe changed and grew over billions of years.

The Millennium Run, as it is dubbed, could help explain observations made by astronomers and shed more light on the Universe's elusive dark energy field.

Details of the study appear in the latest issue of Nature magazine.

"We have learned more about the Universe in the last 10 or 20 years than in the whole of human civilisation," said Professor Carlos Frenk, Ogden professor of fundamental physics at the University of Durham and co-author on the Nature report.

"We are now able, using the biggest, fastest supercomputers in the world, to recreate the whole of cosmic history," he told the BBC.

The researchers looked at how the Universe evolved under the influence of the mysterious material called dark matter.

Dark matter model

According to cosmological theory, soon after the Big Bang, cold dark matter formed the first large structures in the Universe, which then collapsed under their own weight to form vast halos.

The gravitational pull of these halos sucked in normal matter, providing a focus for the formation of galaxies.

The simulation tracked some 10 billion dark matter particles over roughly 13 billion years of cosmic evolution. It incorporated data from satellite observations of the heat left over from the Big Bang, information on the make-up of the Universe and current understanding of the laws of physics on Earth.

"What's unique about the simulation is its scope and the level of detail with which we can re-create the cosmic structures we see around us," Professor Frenk commented.

English Astronomer Royal, Sir Martin Rees told the BBC: "Now we have the Millennium Run simulations, we have the predictions of the theory in enough detail that we can see if there is a meshing together of how the world looks on the larger scale and the way we expect it should look according to our theories. It's a way to check our theories."

Energy problem

Comparisons between the results of the simulation and astronomical observations are already helping shed light on some unsolved cosmic mysteries.

Some astronomers have previously questioned how radio-sources in distant galaxies called quasars could have formed so quickly after the Big Bang under the cold dark matter model.

The Millennium Run simulation demonstrates that such structures form naturally under the model in numbers consistent with data from the Sloan Digital Sky Survey.

The virtual universe may also shed light on the nature of dark energy, which makes up about 73% of the known Universe, and which, Frenk says, is the "number one unsolved problem in physics today - if not science itself".

"Our simulations tell us where to go looking for clues to learn about dark energy. If we want to learn about this we need to look at galaxy clusters, which encode information about the identity of dark energy," Professor Frenk explained.

http://news.bbc.co.uk/1/hi/sci/tech/4600981.stm

 

[Rubyait]

Nasa cuts 'will hamper science'

A major US research body has warned that cuts in Nasa's 2006 budget will hamper progress in understanding our planet and the rest of the Universe.
The American Geophysical Union says there are signs space and Earth science have dropped in priority at Nasa.

The AGU says research in these areas is threatened by the financial demands of meeting President Bush's Moon-to-Mars initiative and other manned programmes.

It also says Nasa is doing "more than it can with the resources provided".

"The problem is that Nasa has a great deal on its plate," said Eric Barron, who has chaired an AGU Panel on the President Bush's Moon-to-Mars vision for space exploration.

"[It] wants to return the space shuttle to flight, finish the space station, [build] the next generation of space transport vehicles as well as exploring the Moon and Mars with humans," Dr Barron told reporters at a news conference in Washington DC.

Satellite losses

Nasa's proposed 2006 budget would reduce science research by about $1.2bn over the next five years.

The AGU said it was particularly concerned about several Earth System Pathfinder missions and Explorer-class satellite missions, which have been eliminated or subjected to prolonged delays.

"These are the smaller, less expensive, flexible, innovative mechanisms that provide frequent access to space," said Dr Barron.

The AGU position statement Nasa: Earth and Space Sciences at Risk says these losses will detrimentally affect weather forecasting, search and rescue, disaster planning and Solar System exploration.

When Nasa announced its proposed 2006 budget in February, it reaffirmed the space agency would continue to be guided by President Bush's vision for space exploration.

This vision, outlined in January 2004, has included a major shift in emphasis towards human exploration, with the intention of returning astronauts to the Moon and, possibly, taking them on to Mars.

The AGU releases a position statement roughly every year.

A Nasa spokesperson was unable to comment on the AGU statement at the time of writing.

http://news.bbc.co.uk/1/hi/sci/tech/4070728.stm

[/i]

 

[Rubyait]

Hubble spies lord of the stellar rings

A spectacular, luminous ring offers the best evidence yet that a nearby star is circled by a newly formed solar system.

The ring is composed of dust particles in orbit around Fomalhaut, a bright star located just 25 light years away in the constellation Pisces Austalis – or the Southern Fish. A recent image captured with the Hubble Space Telescope - which makes the system look uncannily like the Great Eye of Sauron from the blockbusting Lord of the Rings trilogy - confirms that Fomalhaut’s ring is curiously offset with respect to the star.

The most likely explanation is that the gravity of one or more unseen planets is dragging the ring askew. The fact that the inner edge of the ring is relatively well-defined adds further weight to the argument because it suggests the unseen planets are sweeping up stray dust within the radius of the ring.

The image was captured by astronomers at the University of California, Berkeley, US, and NASA’s Goddard Space Flight Center using Hubble’s coronagraph. This device blocks the glare of a star while gathering the faint reflected light from any surrounding ring.

The new image is the first time Fomalhaut’s ring has been seen in visible light. This offers a much sharper view than the infrared wavelengths previously used by astronomers. “We are directly imaging the system,” says team member Paul Kalas. “The offset is unambiguous and it’s been measured with very high accuracy.”

Shining example
Astronomers suspect the ring around Fomalhaut is the dusty trace of a belt of small comet-like bodies that surround the star, much like the Kuiper Belt that surrounds our solar system.

Frequent collisions between these bodies generate enough dust to replenish the ring, which would otherwise be eroded by the star’s radiation in a relatively short time. Since the Kuiper Belt is a by-product of the creation of our solar system, the ring around Fomalhaut may be similarly linked to planet formation. And because Fomalhaut is only 200 million years old - less than 5% of the Sun’s present age - it offers a unique analogue of our solar system’s early years.

While strengthening the case for planets around Fomalhaut, the Hubble image also appears to limit their size. “Fomalhaut is young and any planets that formed around it have yet to cool. Anything larger than about five times the mass of Jupiter would still be glowing warm enough to show up in our image,” says Kalas.

He and his colleagues have already booked time on the Hubble to do follow-up observations later in 2005. They hope to search for small details such as gaps or clumps in the rings that could reveal more precisely the masses and locations of any planets.

http://www.newscientistspace.com/article.ns?id=dn7564

 

[OneWingedBird]

That is a way cool picture.

It looks quite frighteningly like the eye of sauron(!)

 

[Rubyait]

Universe 'too queer' to grasp

Scientist Professor Richard Dawkins has opened a global conference of big thinkers warning that our Universe may be just "too queer" to understand.

Professor Dawkins, the renowned Selfish Gene author from Oxford University, said we were living in a "middle world" reality that we have created.

Experts in design, technology, and entertainment have gathered in Oxford to share their ideas about our futures.

TED (Technology, Entertainment and Design) is already a top US event.

It is the first time the event, TED Global, has been held in Europe.

Species software

Professor Dawkins' opening talk, in a session called Meme Power, explored the ways in which humans invent their own realities to make sense of the infinitely complex worlds they are in; worlds made more complex by ideas such as quantum physics which is beyond most human understanding.

"Are there things about the Universe that will be forever beyond our grasp, in principle, ungraspable in any mind, however superior?" he asked.

"Successive generations have come to terms with the increasing queerness of the Universe."

Each species, in fact, has a different "reality". They work with different "software" to make them feel comfortable, he suggested.

Because different species live in different models of the world, there was a discomforting variety of real worlds, he suggested.

"Middle world is like the narrow range of the electromagnetic spectrum that we see," he said.

"Middle world is the narrow range of reality that we judge to be normal as opposed to the queerness that we judge to be very small or very large."

He mused that perhaps children should be given computer games to play with that familiarise them with quantum physics concepts.

"It would make an interesting experiment," he told the BBC News website.

ET worlds

Our brains had evolved to help us survive within the scale and orders of magnitude within which we exist, said Professor Dawkins.

We think that rocks and crystals are solid when in fact they were made up mostly of spaces in between atoms, he argued.

This, he said, was just the way our brains thought about things in order to help us navigate our "middle sized" world - the medium scale environment - a world in which we cannot see individual atoms.

This idea meant that life was probably "quite common" in the Universe, Professor Dawkins said.

He concluded with the thought that if he could re-engineer his brain in any way he would make himself a genius mathematician.

He would also want to time travel to when dinosaurs roamed the Earth.

More serious focus

Developing world economist and businesswoman Jacqueline Novogratz brought Professor Dawkins' thinking into focus, arguing that we need to fully engage with "developing worlds" to move away from "them and us" thinking.

"The world is talking about global poverty and Africa in ways I have never seen in my life," she said.

"At the same time I have a fear that the victories of G8 will see that as our moral absolution. But that is chapter one; celebrate it, close it and recognise we need a chapter two - a 'how to'.

"The only way to end poverty is to build viable systems on the ground that can deliver services to the poor in ways that are sustainable," she said.

Former Afghan finance minister Ashraf Ghani added that globalisation was "on speed" and needed real private investment and opportunities to flourish.

"Events of 7/7 and 9/11 remind us that we do not live in three different worlds; we live in one world."

He criticised the West for being only concerned with design issues that affect them, and solving environmental problems for themselves.

"You are problem solvers but are not engaging in problems of corruption," he told TED Global delegates.

"You stay away from design for developments. Your designs are selfish; it is for your own immediate use.

"We need your imagination to be brought to bear on problems the way meme is supposed to. It is at the intersection of ideas that new ideas and breakthroughs occur."

More than 300 leading scientists, musicians, playwrights, as well as technology pioneers and future thinkers have gathered for the conference which runs from 12 to 15 July.


http://news.bbc.co.uk/1/hi/sci/tech/4676751.stm

 

[rynner2]

From the World Wide Words newsletter (of all places!):

TATOOINE Real scientists are often avid consumers of SF, so it's
not so strange that astronomer Maciej Konacki of the California
Institute of Technology has borrowed the name of Luke Skywalker's
home planet for an astonishing astronomical object. He has found a
planet far, far away in a system that has three suns, something
previously thought quite impossible. "If you stood on the planet's
surface," the press release says, "you would see three suns in the
sky, although its orbit centers around the main yellow star among
the trio. The larger of the other two suns would be orange and the
smaller would be red." As Dr Konacki says, "The sky view must be
out of this world, literally and figuratively", especially as the
planet's year is only three and a half Earth days long.

First I'd heard of it, but Google has plenty more links. (But most of them seem to be variations of an original press release.)

 

[Rubyait]

Im sure i saw a seperate thread for this but it appears to have vanished during the recent shake up.Anyway i'll stick this here....

Your top 10 names for the tenth planet

On 30 July, the world learned of a new addition to our solar system – a tenth planet. The distant body will receive a name, most probably the as-yet-undisclosed suggestion made by its discoverer, Mike Brown. But wanting to know your opinion, and having provided a few guidelines, we have been overwhelmed by the response.

The top 10 names you suggested, along with the reasons, are below. And we have added a few more of the smartest or most amusing ideas. Thanks for taking part.

1. Persephone (Greek) or Proserpina (Roman)

Many considered this the obvious favourite for naming the new planet, since Roman mythology has it that Pluto (or Hades, in Greek mythology) kidnapped Persephone, and made her his wife. So distraught was Persephone’s mother that her grief created winter. Very apt, since planets do not, as yet, get any colder than our most distant new addition. The only, but significant, problem with this name is that is already taken. As Brown himself points out: “Sadly, the name was used in 1895 as a name for the 399th known asteroid."

2. Peace (or its Latin root, Pax)

In a war-torn world, and with terrorism rife, many of you want to use the new planet to send a message. Patricia Schiavone, of Montevideo, Uruguay summed it up: “I'd call it Pax because we all feel peace to be very far away, yet it reflects what most people were wishing for when this new planet was discovered."

3. Galileo

Often referred to as the “father of modern astronomy” and credited with construction of the first astronomical telescope, Galileo was the leading suggestion for naming the new planet after a real person. Guillermo Dotto in Buenos Aires, Argentina, summed up voters' feelings: “I would name it after Galileo, the genius who provided the means to search outer space.”

Other votes for real people included Isaac Newton, Brahms, Isaac Asimov, Nelson Mandela, Mahatma Gandhi, Albert Einstein, Carl Sagan, Euclid, Stephen Hawking, Mother Theresa, Copernicus, Aristotle and Arthur C Clarke.

4. Xena

Xena, after TV’s Warrior Princess, was the name Mike Brown and his team gave the planet upon first discovering it. He later said “that was our tongue-in-cheek internal name, never intended for public consumption". Nevertheless, the mythical-sounding name caught your imagination. And, as Andrew Gregurich of Michigan, US, pointed out: “You could stick with Xena. She might not like it if you changed the name. HIYAH!”

5. Rupert

It might seem like an unlikely name for a planet, and it probably would be. But in the fourth book of the Hitch-hikers Guide to the Galaxy “trilogy” - Mostly Harmless - author Douglas Adams describes a tenth planet around the Sun: “The planet was named Persephone, but rapidly nicknamed Rupert after some astronomer's parrot - there was some tediously heart-warming story attached to this - and that was all very wonderful and lovely.”

6. Bob

This name tickled many a funny bone, it seems. Raffy E, in California, US, explains his reasons for choosing it: “It's one word, easy to pronounce, inoffensive, and imagine the jokes that'll come out of the scientific community for years after! Also, I think Uranus needs a break, don't you?”

7. Titan

This was another popular choice, but again has already been taken, as those of you who have been reading our Cassini: Mission to Saturn special report already know. The report contains several stories of the Cassini mission’s discoveries on Titan - a giant moon around Saturn.

8. Nibiru

Nibiru, is the name ancient Babylonians gave to a heavenly body associated with their chief deity, Marduk. According to ancient Sumerian tablets, it also referred to a mysterious Planet X – at that time undiscovered. Some voters believe that the writings have now come true. Others, like Mario De Leo of Mexico City, Mexico, just like the idea of it: “It's easy, short, nice sounding and has a big, big story behind it.”

9. Cerberus

Cerberus is the three-headed beast that guarded the gates of Hades (the Greek underworld). Alex Ijzerman, of the Netherlands, says: “In mythology Cerberus is the guard-dog of the Greek underworld. He’s the solar system's guard dog, you could say. Beyond it lies undiscovered country into which we are unable to pass at this moment.”

10. Loki

This Norse god of mischief is described by Wikipedia as “a master of guile and deception - not so much a figure of unmitigated badness as a kind of celestial con man”. Many readers thought this persona suited the tenth planet very well. Vern, in Massachusetts, US, agrees wholeheartedly: “Loki has similar underworld associations as Pluto but in the Norse mythology. And, because this discovery has instigated such a difficult debate about what is or is not a planet, the name of a "trickster" who causes such trouble is right on the money.”

The power of 10
Many voters liked the idea of naming the planet based its tenth position in the heavens: Decimal, Dekatos, Planet X, Decanus, Decimus, X, Decadia, Deka, Deca and even Dekatoo.

Dishan Marikar, of Victoria, Australia, suggested the name Bolero, “as it was famously used in the soundtrack for the movie 10 with Bo Derek and Dudley Moore.

And we also had several votes for the name Maradona. Curiously, our Argentinean readers all seem to agree that footballer Diego Maradona is the best number 10 that ever lived.

And finally…
Some people chose to take an especially original approach to the challenge of suggesting the planet's name. Here are our favourites:

Julian, from Brisbane, Australia, wrote: “I think the new planet should be called Namakakiweyho. Why? Because I think it's a great sounding name, and it's probably never been used for anything before!”

Jessika Scheuenstuhl, in California, US, wrote: "My planet name is Cananeesta. My father used to make up bedtime stories for me, and Cananeesta was his main character. She was a space traveller who loved peanut butter and jelly sandwiches.

David Field, in Kingsbridge, UK, wrote: “My proposed name is Selsia. This was the name of an unforgettably pretty young lady from my adolescence, nearly 60 years ago.”

Colton Harris, in Illinois, US, provided our editor’s favourite response, when he wrote: “My suggestion for the new planet’s name is R2D2. I am a 6 year old boy, I want to be the first human being to walk on the planet Mars!”

http://www.newscientistspace.com/article/dn7811

 

[sunsplash1]

Aboriginal astronomers see mythology in stars
Aboriginal bark paintings, stories and historical archives are helping an astrophysicist to learn more about Indigenous Australians' long history of documenting stars in the southern sky.

Dr Ragbir Bhathal of the University of Western Sydney is delving into a wealth of astronomical information buried in archives at the National Library of Australia.

This includes written records of public servants, pastors, writers, scholars and explorers who spoke to local Aboriginal people and documented their stories as they travelled the strange new southern land.

He also plans to travel to Arnhem Land, in the Top End, to hear Aboriginal stories first-hand.

Aboriginal Australians were the first to document stars in the southern hemisphere.

Some are still using the stars to guide hunting and food gathering, and as a source of moral instruction passed down through oral history.

In this way Aboriginal people combine a rich cosmic mythology with observational astronomy, Mr Bhatal says.

Early Indigenous astronomers named the constellations after the animals with which they shared the continent, including kangaroos, cockatoos and fish.

For example, the constellation Orion represents an emu.

"Just like the Greeks had mythologies about gods and goddesses in the sky the Aboriginal people have built their own mythology about the night sky," Mr Bathal said.

Aboriginal stories also help to explain social relations and the origins of life.

Indigenous astronomers of Arnhem Land say the Southern Cross is a stingray chased by a shark. The Milky Way is a river filled with fish and lily "sky people" and the Magellanic Clouds represent an old man and woman by a campfire.

The Sun is an egg thrown into the sky by a brolga after an argument with an emu over whose chicks are the most beautiful.

Children need to know

Mr Bhathal, the director of the university's observatory, says Aboriginal astronomy should be taught to children, just as ancient Greek astronomy is included in courses on the history of astronomy.

He says while the belief systems of Indigenous Australians do not necessarily add any scientific value to modern Western astronomy, they show how different people understand their universe.

"I think every child in Australia should know about Aboriginal astronomy; it is part our heritage," he said.

Mr Bhathal says there has recently been a surge in interest around the world in the astronomy of other cultures and Inca, ancient Chinese, native American and Arabic systems are also being revisited.Last

Updated:Tuesday, August 16, 2005. 6:00pm (AEST)http://www.abc.net.au/news/newsitems/200508/s1439086.htm

Full details at-
http://www.abc.net.au/science/news/stories/s1437646.htm

Crikey! Astronomy from an Indigee perspective. The sun is an Egg thrown into the sky by a Brolga?, makes sense to me! 8)

 

[Rubyait]

Run for your lives, or walk. Or dont bother, unless you immortal...


Telescope views death of galaxy

Two galaxies collide in the constellation of Pisces, some 100 million light-years away from Earth.
Astronomers say it gives a scary insight into what may happen to our own planet some 5 billion years from now.

The Milky Way is expected to merge with the neighbouring Andromeda Galaxy, swallowing up the Solar System.

The image was captured last month by an instrument on the Gemini North Telescope at Mauna Kea, Hawaii.

Professor Ian Robson, Director of the UK Astronomy Technology Centre, which built the instrument, said that when he first saw the image, it sent shivers down his spine.

"Our saving grace is that we have about 5 billion years left before we get swallowed up by Andromeda," he said.

"Nevertheless, it's amazing to see so far in advance how planet Earth and our own galaxy will ultimately end. Glad to say I won't be around when the fireball happens."

The combined galaxies, known as NGC 520, have lost their shape as a result of the collision. Astronomers believe new stars are forming in the faint red glowing areas seen above and beneath the middle of the image.

It is one of many snapshots of distant galaxies and star forming regions taken by the Gemini Multi-Object Spectrograph (GMOS) since it was installed in 2001.

http://news.bbc.co.uk/1/hi/sci/tech/4189278.stm

 

[Rubyait]

Hubble reveals new map of Pluto

Astronomers have produced a new colour map of Pluto, the most distant planet in our Solar System, using images from the Hubble Space Telescope.

The detailed map shows areas likely to be methane frost and a bright spot perhaps made of frozen carbon monoxide.

And another team has obtained the most precise estimate yet for the size of its moon, Charon, with data gathered during the planet's eclipse of a star.

This figure could be used to calculate a more accurate size for Pluto itself.

The US space agency's (Nasa) New Horizons spacecraft will set off for an encounter with Pluto and Charon next year, but will not arrive until 2015 at the earliest.

Until then, astronomers say they will continue to seek insights into this mysterious world and its lone satellite.

Dirty water

The latest global map was produced using data obtained by Hubble's Advanced Camera for Surveys (ACS) between July 2002 and June 2003.

The telescope worked over 12 orbits and looked through two filters. Producing the map has taken two years of computer processing.

The researchers, led by Marc Buie of the Lowell Observatory, have found dark areas thought to be dirty water-ice and brighter ones indicating nitrogen frost. Red areas indicate methane ice and possibly other organics (carbon-based molecules).

The methane frost seems to be everywhere, running into dark and light areas on "a hemispheric level", said Dr Buie.

An unusual bright spot near the centre of the global map could indicate the presence of carbon monoxide, said Dr Buie. The Lowell Observatory researcher said he had asked members of the New Horizons team to investigate this area with their spacecraft.

An accurate measurement of Charon's radius and density were obtained from observations made during the moon's occultation on 11 July 2005. During this occultation, the moon eclipsed, or hid, a star.

Bruno Sicardy, from the Paris Observatory, France, and colleagues used the data from this event to tie down the radius of Charon to 602.5km, plus or minus one kilometre - the most precise figure yet obtained for its size.

Previous observations had given a lower limit for Charon's size, but could not say how big it might be.

From the new radius, Dr Sicardy's team was able to determine a very accurate density for Charon of 1.73 (plus or minus 0.08) grams per cubic centimetre.

Planet under question

Astronomers can now re-analyse data on Pluto gathered in the 1980s using the new figures for Charon's size and density to better constrain these values for Pluto itself.

Recent discoveries in the outer Solar System have cast doubt on Pluto's status as a planet. Some think it is simply the first historically recorded representative of a larger family of distant bodies known as Kuiper belt objects.

Dr Buie explained that Pluto seemed to be very similar to Neptune's moon Triton, which is thought to be a Kuiper belt object captured by Neptune's gravity. This is despite the fact that the process of capture should have altered Triton's surface drastically through heating.

"I'm surprised Triton and Pluto aren't more different than they are," he told the BBC News website.

The primary launch window for the New Horizons mission runs from 11 January-14 February 2006. If it launches within that window, it will swing by Jupiter for a gravity assist and arrive at Pluto in 2015.

http://news.bbc.co.uk/1/hi/sci/tech/4230918.stm

Edit: the dude with the specs on is supposed to be 8.Why it showed as 'a dude with specs on' i dont know.

 

[Rubyait]

Most distant cosmic blast sighted

Astronomers have witnessed the most distant cosmic explosion on record: a gamma-ray burst that has come from the edge of the visible Universe.
Gamma-ray bursts are intense flares of high-energy radiation that appear without warning from across the cosmos.

They can release as much energy in a few minutes as our Sun will emit in its expected 10-billion-year lifetime.

The blast was observed by the Swift space telescope and by a number of ground-based observatories.

The latest, record gamma-ray burst was detected on 4 September, 2005, and lasted about three minutes. It probably marked the death of a massive star as it collapsed into a black hole.

It has a so-called redshift of 6.29, which translates to a distance of about 13 billion light-years from Earth.

Used by astronomers to measure cosmic distances, redshift refers to the extent to which light is shifted towards the red part of the electromagnetic spectrum during its long journey across the Universe. The greater the distance, the higher the redshift.

Record distance

"This burst smashes the old distance record by 500 million light-years," said Dr Daniel Reichart, of the University of North Carolina, US, who has been leading the measurement of its distance.

Professor Keith Mason, chief executive of the UK's Particle Physics and Astronomy Research Council (PParc), which helped fund Swift, commented: "This is an amazing result that will enable us to find out more about stars from near the beginning of time."

By studying objects at this distance, astronomers are looking into the Universe's early times. The burst comes from an era soon after stars and galaxies first formed, about one billion years after the Big Bang.

Dr Nial Tanvir, of the University of Hertfordshire, UK, who is an investigator on the Swift mission, said the telescope could yet spot more distant bursts hailing from even earlier stages in the Universe's evolution.

"I think you could see them just a few hundred million years after the Big Bang. We don't know whether there were any stars at that time, but we should be able to see them at that distance if there were," he told the BBC News website.

Window on the past

The early Universe was smooth and homogeneous, a contrast to the clumpy array of galaxies and clusters observed today.

Observing events like this on the far edges of the visible Universe can help astronomers understand how this evolution took place.

It is thought that only the elements hydrogen and helium were produced by the Big Bang - everything else was "cooked up" by the first stars.

These early stars may have been quite different from those that exist today - for example, some researchers think they may have been much more massive.

"We can get an idea about that by looking at the debris they produced after exploding," said Dr Tanvir.

Scientists on four continents, using a variety of telescopes, have been tracking the burst and its afterglow as it gradually faded.

Astronomers plan to use the Hubble Space Telescope for observations at the end of the month, although the burst will have dimmed substantially by this time.

http://news.bbc.co.uk/1/hi/sci/tech/4237800.stm

 

[OneWingedBird]

Used by astronomers to measure cosmic distances, redshift refers to the extent to which light is shifted towards the red part of the electromagnetic spectrum during its long journey across the Universe. The greater the distance, the higher the redshift.

Is that accurate? I'd thought red shift was purely a velocity related thing?

 

[rynner2]

Used by astronomers to measure cosmic distances, redshift refers to the extent to which light is shifted towards the red part of the electromagnetic spectrum during its long journey across the Universe. The greater the distance, the higher the redshift.

Is that accurate? I'd thought red shift was purely a velocity related thing?

Red shift is velocity related, but in an expanding universe velocity of recession increases with distance, thus linking red shift and distance.

Allegedly! 8)

 

[OneWingedBird]

Red shift is velocity related, but in an expanding universe velocity of recession increases with distance, thus linking red shift and distance.

Gotcha - I think they just worded it funny, sort of implying the shifting happened during the journey rather than at source - wasn't sure for a second if they were bringing in some of the 'alternative' astronomy theories on ultra finely dispersed matter in interstellar/intergalactic space being able to create the same shifting effect (and thus a faux red shift which isn't a true indication of velocity).

 

[ramonmercado]

Black Hole Lurks in Invisible Galaxy

Black Hole Lurks in Invisible Galaxy
By Ker Than
Staff Writer
posted: 14 September 2005
1:00 p.m. ET


In a strange reversal, astronomers have detected a massive black hole but can find no traces of the surrounding galaxy that should be feeding it.

At the center of most large galaxies, our own Milky Way included, are extremely dense black holes that have masses hundreds of millions times that of the Sun.

Called quasars, these massive black holes are the most radiant objects in the universe, outshining even the brightest galaxies. While the black holes themselves are undetectable, friction and heat from the swirling matter they ingest emit huge amounts of radiation that can be detected by radio telescopes.

To maintain their fierce brightness, however, quasars must feed off the very galaxies they live within. That is why the discovery of a galaxy-less quasar is so surprising.

Using images from the Hubble Space Telescope and spectroscopy from the Very Large Telescope (VLT) in northern Chile, an international team of astronomers selected 20 quasars located at moderate distances from Earth to study the properties of their host galaxies.

In 19 of them, the astronomers found encircling galaxies as predicted. But when they looked at HE0450-2958, a quasar located some 5 billion light-years away, they didn’t find any sign of a galaxy.

“We must therefore conclude that, contrary to our expectations, this bright quasar is not surrounded by a massive galaxy,” said Pierre Magain, an astronomer from the University of Liege in Belgium and lead author of a new study documenting the finding.

Quasars are relatively small compared to the galaxies they outshine. They are only about the size of our solar system, but they can emit up to 100 times as much radiation as an entire galaxy.

While the intense brilliance of quasars make them visible from clear across the universe, it also makes detection of their host galaxies difficult because light and radiation from the galaxies get lost in the glare of the quasars.

In the late 1990s, mathematical “deconvolution” algorithms were developed that could be applied to images after they were transmitted to Earth and which were capable of separating light from quasar’s from that of their host galaxies. Since then, astronomers have shown that nearly all quasars are encircled by a host galaxy.

Instead of a galaxy, the researchers detected a cloud of ionized gas about 2,500 light years in size near HE0450-2958. Dubbed “the blob,” the researchers believe this gas cloud is what’s feeding the black hole, allowing it to become a quasar. The researchers estimate that the quasar is siphoning off about one Sun’s worth of mass each year from blob to satisfy its ravenous appetite.

Adding to the mystery is the detection of a deeply distorted galaxy located 50,000 light years away from the quasar. This so-called “companion” galaxy appears to be an extremely active stellar nursery, birthing new stars at a rapid rate, and it is also brighter in the infra-red spectrum than most galaxies.

The combination of these three factors—distorted shape, high rate of star production and ultra infra-red luminosity—suggests to the researchers that the companion galaxy suffered a cosmic collision about 100 million years ago, possibly with the galaxy-less quasar.

Such a collision would have stirred up dust and gas and enhanced the formation of stars, said Gèraldine Letawe, a member of the research team also from University of Liege in Belgium. Heat from the seething young stars, combined with dust and gas warmed up by the collision might be responsible for the galaxy’s intense infra-red glow.

To explain the strange cosmic setup they’ve discovered, the researchers have come up with various hypotheses, all of them equally strange:

It’s possible that the quasar does have an encircling galaxy, but that it is too small and too faint to be detected. If a host galaxy does exist, then it would have be to either six times fainter than typical host galaxies or have a radius smaller than 300 light years. Most quasar host galaxies range between 6,000 and 50,000 light years across.
The quasar may not have always been galaxy-less, but the collision with the companion galaxy may have somehow caused the quasar’s galaxy to disappear completely. The researchers note, however, that it is “hard to imagine how the complete disruption of a galaxy could happen.”
The blob could be gas stolen by a slow-moving black hole as it traveled through the disc of a spiral galaxy.
Perhaps the most intriguing theory is that the quasar is encircled by a galaxy made up almost entirely of dark matter, a theoretical substance which is thought to make up 25 percent of the matter in the universe but which cannot be directly detected using current technologies.
Computer simulations of galaxy collisions might be able to determine if the first two options are plausible, Letawe told SPACE.com in an email interview.

It may be possible to verify whether the galaxy is made up of dark matter by scanning the space around the quasar for evidence of gravity lensing, a phenomenon whereby a massive celestial object warps the fabric of space-time so much that light from distant objects is bent around it.

Another way to test for the presence of a dark matter galaxy is to look for gases that appear to be moving as if drawn by the gravity of some unseen object, Letawe said.

The discovery is documented in the September 15 issue of the journal Nature.

http://www.space.com/scienceastronomy/0 ... uasar.html

 

[Rubyait]

Mysterious ring of stars guards Andromeda’s heart

The Milky Way's near-twin galaxy, Andromeda, harbours a supermassive black hole at its core that is surrounded by an unexpected and unexplained disc of young stars.

These new observations by the Hubble Space Telescope answer one longstanding mystery: the source of bright blue light very close to the spiral galaxy's central black hole, first spotted using Hubble a decade ago. Yet solving this mystery has immediately created another in its place.

The newly discovered disc is composed of over 400 very hot, young blue stars, orbiting like a planetary system very close to the black hole. That puzzles astronomers because the black hole's intense gravitational field should have torn apart any clouds of matter long before they could coalesce to form new stars.

The stars form a very flat disc that is only one light year across. An elliptical disc of older red stars surrounds it, spanning about five light years. Since the two discs appear to be in the same plane, they are probably related, but no one yet understands how either disc came into being.

It’s not unusual?
Spectroscopic observations made with Hubble's Space Telescope Imaging Spectrograph (STIS) show that the disc of blue stars is only about 200 million years old, while the galaxy itself has been around for about 12 billion years. Intriguingly, there are signs of young stars very close to the core of our own galaxy as well.

So this puzzling phenomenon may not be unusual, says Hubble team member Tod Lauer of the National Optical Astronomy Observatory in Tucson, Arizona, US.

Since it would be surprising if astronomers happened to catch the only example of such a young disc, it may be that such rings are constantly being formed, he says.

"This behaviour may not be the exception but the rule," he adds. "We still don't know, however, how such a disc could form in the first place. It’s an enigma."

Supermassive black hole
Measurements by the STIS instrument also allowed astronomers to determine the movement of the blue stars and therefore pinpoint the black hole's mass.

This proved conclusively that it really is a supermassive black hole, with a mass 140 million times that of our Sun - three times more massive than previous estimates.

Until these observations, it had been impossible to rule out some highly unlikely alternatives for the object in the centre of the galaxy - including an extremely dense star cluster, says team member John Kormendy at the University of Texas, US.

"Nailing the black hole in Andromeda" will be remembered as one of Hubble's most important findings, Kormendy says. "It makes us much more confident that the other central dark objects detected in galaxies are black holes too."

http://www.newscientistspace.com/article.ns?id=dn8025

 

[rynner2]

The stars form a very flat disc that is only one light year across. An elliptical disc of older red stars surrounds it, spanning about five light years. Since the two discs appear to be in the same plane, they are probably related, but no one yet understands how either disc came into being.

Perhaps this an example of stellar engineering by an advanced life-form... :shock: :shock: :shock:

 

[Rubyait]

Perhaps this an example of stellar engineering by an advanced life-form...

Yeah its quite weird! I mean to know that this may be a patten but one that apparently contradicts itself. :?

 

[eburacum]

Andromeda might be swarming with advanced civilisations and with stellar engineering; but we don't see it in our galaxy.
Ah well; we only have to wait a few billion years and Andromeda will collide with the Milky Way- then they'll probably come and take over all this empty real estate.

 

[Timble2]

Andromeda might be swarming with advanced civilisations and with stellar engineering; but we don't see it in our galaxy.
Ah well; we only have to wait a few billion years and Andromeda will collide with the Milky Way- then they'll probably come and take over all this empty real estate.

It's the Xeelee building their escape hatch from the universe and they'll be out of here before the galaxies collide.

 

[KeyserXSoze]

Source

'Big baby' galaxy detected in early universe
Sep 27 1:43 PM US/Eastern

By Deborah Zabarenko

WASHINGTON (Reuters) - Astronomers using two of NASA's most powerful telescopes said on Tuesday they have detected a "big baby" galaxy, vastly heavy for its young age and its location in the early universe.

The discovery was surprising, since astronomers have long theorized that galaxies form when stars gradually cluster together, with small galaxies preceding bigger galaxies.

But the stars in this cosmic infant -- less than 1 billion years old -- have eight times the mass of those in the 13-billion-year-old Milky Way, which contains Earth.

The young galaxy was found by researchers using NASA's Hubble and Spitzer space telescopes who looked back in time to a point some 800 million years after the Big Bang explosion that many scientists believe gave birth to the universe.

The discovery of this massive, well-developed galaxy at such an early point in time means astronomers may have to adjust their ideas on when galaxies and other cosmic objects can form, said Massimo Stiavelli of the Space Telescope Science Institute, which deals with Hubble's findings.

"It means that the process of galaxy formation started really very early on," Stiavelli said in a telephone interview. "It pushes back things like first light, which is the thing we are all hunting for."

FOUND IN HUBBLE SURVEY

Before the emergence of the first light source, the universe is thought to have been suffused with a generic glow, caused by microwave background radiation from the Big Bang.

The galaxy, known as HUDF-JD2, was hiding in a tiny patch of sky -- about one-tenth the size of the full moon -- known as the Hubble Ultra Deep Field, because the Hubble Space Telescope made a detailed survey of this area.

Rather than a two-dimensional picture, the Hubble survey is a bit like a core sample of the cosmos, peering narrowly into the vast distance of space, and therefore back in time about 13 billion years.

Even Hubble's keen cameras could not see this galaxy in visible light; it was only detected in infrared images made by Hubble and an infrared camera at the European Southern Observatory in Chile. In general, older astronomical objects appear redder than younger objects.

The Spitzer telescope, which is sensitive to the light from older, redder stars, found the baby galaxy to be unexpectedly bright in infrared light, suggesting a very massive object, especially for its early era.

"This would be quite a big galaxy even today," said Mark Dickinson of the National Optical Astronomy Observatory and lead scientist for the Spitzer results. "At a time when the universe was only 800 million years old, it's positively gigantic," Dickinson said in a statement.

These findings are to be reported in November and December in the Astrophysical Journal.

More information and images are available at >http://hubblesite.org/news/2005/28.

 

[ramonmercado]

Unusual Meteorite Unlocks Treasure Trove Of Solar System Sec

Unusual Meteorite Unlocks Treasure Trove Of Solar System Secrets

Dr. Munir Humayun.
Tallahassee FL (SPX) Sep 28, 2005
An unusual meteorite that fell on a frozen lake in Canada five years ago has led a Florida State University geochemist to a breakthrough in understanding the origin of the chemical elements that make up our solar system.
Professor Munir Humayun of the National High Magnetic Field Laboratory and the geological sciences department at FSU and Alan Brandon of NASA discovered an isotopic anomaly in the rare element osmium in primitive meteorites. The anomalous osmium was derived from small stars with a higher neutron density than that which formed our solar system.

The findings of the researchers, who also included colleagues from the University of Maryland and Bern University in Switzerland, were recently published in the journal Science.

"Our new data enabled us to catch a glimpse of the different star types that contributed elements to the solar system, the parental stars of our chemical matter," Humayun said. "It opens a treasure trove of prospects for exploring the formation of the elements."

For about 50 years, scientists have known that all the elements beyond iron in the periodic table were made in stars by up to three nuclear processes. Osmium is mainly formed by two of those processes, the so-called s-process in which neutrons are slowly added to nuclei over a period of perhaps thousands of years in aging, medium-size stars and the r-process that occurs in supernovae in which neutrons are pumped into nuclei at a rate of hundreds of neutrons in a few seconds.

The new data gathered by Humayun's team not only shows the different star types that contribute elements to the solar system, it also will be used to test astrophysical models of production of the chemical elements at a more sophisticated level than previously possible, he said.

Humayun and colleagues studied samples from an extremely fragile meteorite that fell on Tagish Lake on Jan. 18, 2000. Unlike iron meteorites, primitive meteorites like this one are not preserved long on the Earth's surface because they disintegrate and form mud when exposed to water. This one was retrieved within 48 hours of its fall in the dead of an Arctic winter.

Most meteorites have a uniform osmium isotopic distribution, but Humayun's team found that osmium extracted from the Tagish Lake meteorite was deficient in s-process osmium. They are the first to report an anomaly in the isotopic makeup of the element osmium from meteorites.

Other researchers have found isotope anomalies in several other elements in some primitive meteorites, but not in others. Because of the disparity, scientists believed that the ashes of stars that preceded the solar system must have been sprinkled in a non-uniform way into the solar nebula, the disk of gas and dust that formed the sun, planets and meteorites. Scientists had hypothesized that some of the dust could have been created by an active nearby star.

Humayun's findings challenge that explanation. He believes that the anomaly is an expression of presolar stardust that survived the homogenization that affected nearly all other meteorites.

Typically, stardust accretes to form meteorites and is then heated by radioactivity - a process that destroys the silicon carbide grains that are the carriers of the anomaly. But in the case of the meteorites with osmium isotopic anomalies, the heat was not significant enough to destroy the silicon carbide.

"The previous interpretation of incomplete mixing of different sources of dust at the scale of the solar nebula no longer seems tenable," he said.

"We now interpret those anomalies as incomplete dissolution of silicon carbide grains that carried traces of molybdenum, ruthenium and osmium. These anomalies reveal that the raw materials from which our solar system was built are preserved in a few exceptional meteorites, from which we can now recover the prehistory of our solar system."

http://www.spacedaily.com/news/meteor-05e.html

 

[ramonmercado]

Mature Galaxy Found In Early Universe

Mature Galaxy Found In Early Universe
Eight Times More Massive Than Milky Way

This image demonstrates how data from two of NASA's Great Observatories, the Spitzer and Hubble Space Telescopes, are used to identify one of the most distant galaxies ever seen. This galaxy is unusually massive for its youthful age of 800 million years. (After the Big Bang, the Milky Way by comparison, is approximately 13 billion years old.)

- The galaxy, named HUDF-JD2, was pinpointed among approximately 10,000 others in a small area of sky called the Hubble Ultra Deep Field (HUDF). This is the deepest image of the universe ever made at optical and near-infrared wavelengths.

[Upper Right] - A blow-up of one small area of the HUDF is used to identify where the distant galaxy is located (inside green circle). This indicates that the galaxy's visible light has been absorbed by traveling billions of light-years through intervening hydrogen.

[Center Right] - The galaxy was detected using Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS). But at near-infrared wavelengths it is very faint and red.

[Bottom Right] - The Spitzer Infrared Array Camera (IRAC), easily detects the galaxy at longer infrared wavelengths. Spitzer's IRAC is sensitive to the light from older, redder stars which should make up most of the mass in a galaxy. The brightness of the infrared galaxy suggests that it is quite massive.

Credit: NASA, ESA, B. Mobasher (Space Telescope Science Institute and the European Space Agency).

Pasadena CA (SPX) Sep 28, 2005
A massive galaxy seen when the universe was only 800 million years old has been discovered by teams of astronomers using NASA's Spitzer and Hubble Space Telescopes.
The galaxy's large mass and maturity come as a surprise, because experts previously thought that early galaxies in the young universe should be less prominent agglomerations of stars, rather than giant collections of hundreds of billions of stars as populous or more so than the Milky Way.

The researchers are particularly intrigued by the fact that star formation in the galaxy seems to have already been completed. This implies that the bulk of the activity that built up the galaxy had occurred even earlier.

"This is truly a significant object," says Richard Ellis, who is the Steele Family Professor of Astronomy at the California Institute of Technology and a member of the discovery team. "Although we are looking back to when the universe was only 6 percent of its present age, this galaxy has already built up a mass in stars eight times that of the Milky Way.

"If the distance measurement to this object holds up to further scrutiny, the fact such a galaxy has already completed its star formation implies a yet earlier period of intense activity," Ellis adds.

"It's like crossing the ocean and meeting a lone seagull, a forerunner of land ahead. There is now every reason to search beyond this object for the cosmic dawn when the first such systems switched on!"

The galaxy was pinpointed among approximately 10,000 others in a small patch of sky called the Hubble Ultra Deep Field (UDF). It is believed to be about as far away as the most distant galaxies known.

Bahram Mobasher of the Space Telescope Science Institute, leader of the science team, explains, "We found this galaxy in Hubble's infrared images of the UDF and expected it to be young and small, like other known galaxies at similar distances. Instead, we found evidence that it is remarkably mature and much more massive. This is the surprising discovery."

The galaxy's great distance was deduced from the fact that Hubble does not see the galaxy in visible light (despite the fact that the UDF is the deepest image ever taken in optical light).

This indicates that the galaxy's blue light has been absorbed by traveling billions of light-years through intervening hydrogen gas. The galaxy was detected using Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS), and with an infrared camera on the Very Large Telescope (VLT) at the European Southern Observatory. At those near-infrared wavelengths it is very faint and red.

The big surprise is how much brighter the galaxy is in images at slightly longer infrared wavelengths from the Spitzer Space Telescope. Spitzer is sensitive to the light from older, redder stars, which should make up most of the mass in a galaxy. The infrared brightness of the galaxy suggests that it is very massive.

Two other Spitzer observations, one reported earlier by Ellis and his colleagues at the University of Exeter, UK, and the other by Haojing Yan of the Spitzer Science Center, had already revealed evidence for mature stars in more ordinary, less massive galaxies at similar distances, when the universe was less than one billion years old.

However, the new observation extends this notion of surprisingly mature galaxies to an object which is perhaps ten times more massive, and which seemed to form its stars even earlier in the history of the universe.

The team estimated the distance to this galaxy by combining the information provided by the Hubble, Spitzer, and VLT observations. The relative brightness of the galaxy at different wavelengths is influenced by the expanding universe, and allows astronomers to estimate its distance. At the same time, they can also get an idea of the make-up of the galaxy in terms of the mass and age of its stars.

Efforts by Dan Stark, a graduate student at Caltech, using both the giant 10 m Keck and 8 m Gemini telescopes failed to pinpoint the galaxy's distance via spectroscopic methods-the astronomers' conventional tool for estimating cosmic distances.

"We have to admit," says Stark, "that we have now reached the point where we are studying sources which lie beyond the spectroscopic capabilities of our current ground-based facilities. It may take the next generation of telescopes, such as the James Webb Space Telescope and Caltech's proposed Thirty Meter Telescope, to confirm the galaxy's distance."

While astronomers generally believe most galaxies were built up piecewise by mergers of smaller galaxies, the discovery of this object suggests that at least a few galaxies formed quickly and in their entirety long ago. For such a large galaxy, this would have been a tremendously explosive event of star birth.

The findings will be published in the December 20, 2005, issue of the Astrophysical Journal.

http://www.spacedaily.com/news/stellar- ... -05ze.html
​

​

 

[ramonmercado]

'Missing' Dark Matter Is Really There

'Missing' Dark Matter Is Really There, Says Hebrew University Cosmologist

A new analysis that refutes challenges to the existence of dark matter in certain galaxies appears in an article published this week in the journal Nature. Leading author of the article is Avishai Dekel, professor of physics at the Hebrew University of Jerusalem.

Accepted cosmological theory postulates that every observable galaxy in the universe (each made up of billions of stars similar to our sun) is embedded in a massive “halo" of dark matter. Though unseen, dark matter can be clearly detected indirectly by observing its tremendous gravitational effects on visible objects.

This common understanding faced a severe challenge when a team of astronomers, writing in Science in 2003, reported a surprising absence of dark matter in one type of galaxy – “elliptical" (rounded) galaxies. Their theory was based on observations that stars located at great distances from the center in such galaxies move at very slow speeds, as opposed to the great speed one would have expected from the heavy gravitational pull exerted by dark matter.

The new analysis in Nature provides a simple explanation for these observations. “In fact,” says Dekel, “our analysis fits comfortably with the standard picture in which elliptical galaxies also reside in massive dark matter halos.

"A dearth of dark matter in elliptical galaxies is especially puzzling in the context of the common theory of galaxy formation, which assumes that ellipticals originate from mergers of disk galaxies," added Dekel. "Massive dark-matter halos are clearly detected in disk galaxies, so where did they disappear to during the mergers?" asks Dekel.

The Nature article is based on simulations of galaxy mergers run on a supercomputer by graduate student Thomas J. Cox, supervised by Joel Primack, a professor of physics at the University of California, Santa Cruz. The simulations were analyzed by Dekel and collaborators Felix Stoehr and Gary Mamon at the Institute of Astrophysics in Paris, where Dekel is the incumbent of the Blaise Pascal International Chair of Research at the Ecole Normale Superieure.

The simulations show that the observations reported in Science are a predictable consequence of the violent collision and merger of the spiral galaxies that lead to the formation of the elliptical galaxies.




Illustration of computer simulation showing two spiral galaxies combining to form an elliptical galaxy at right.

Evidence for dark matter halos around spiral galaxies comes from studying the circular motions of stars in these galaxies. Because most of the visible mass in a galaxy is concentrated in the central region, stars at great distances from the center would be expected to move more slowly than stars closer in. Instead, observations of spiral galaxies show that the rotational speed of stars in the outskirts of the disk remains constant as far out as astronomers can measure it.

The reason for this, according to the dark matter theory, is the presence of an enormous halo of unseen dark matter in and around the galaxy, which exerts its gravitational influence on the stars. Additional support for dark matter halos has come from a variety of other observations.

In elliptical galaxies, however, it has been difficult to study the motions of stars at great distances from the center. The scientists writing in Science found a decrease in the velocities with increasing distance from the center of the galaxy, which is inconsistent with simple models of the gravitational effects of dark matter halos.

Part of the explanation for that phenomenon, put forth in the new Nature paper, lies in the fact that the velocities in the earlier study were measured along the line of sight. "You cannot measure the absolute speeds of the stars, but you can measure their relative speeds along the line of sight, because if a star is moving toward us its light is shifted to shorter wave lengths, and if it is moving away from us its light is shifted to longer wave lengths," Primack explained.

This limitation would not be a problem if the orbits of the observed stars were randomly oriented with respect to the line of sight, According to Cox's simulations, however, the stars in elliptical galaxies that are farthest from the center are likely to be moving in elongated, eccentric orbits such that most of their motion is perpendicular to the line of sight. Therefore, they could be moving at high velocities without exhibiting much motion toward or away from the observers.

Why this is so is traceable to the processes whereby disk galaxies merge to form elliptical galaxies. "In the merger process that produces these galaxies, a lot of the stars get flung out to fairly large distances, and they end up in highly elongated orbits that take them far away and then back in close to the center," explained Dekel.

"If we see a star at a large distance from the center of the galaxy, that star is going to be mostly moving either away from the center or back toward the center. Almost certainly, most of its motion is perpendicular to our line of sight," Dekel said. Under such circumstances, the star would appear to be moving quite slowly, when in fact this is not the case, based upon the models of simulated galaxy mergers studied by the Hebrew University-UCSC-Paris team.


"Our conclusion is that what the cosmologists described in 2003 is exactly what the dark matter model would predict," he said, “Our findings remove a problem which bothered them and make it possible to better understand the processes involved in creation of new galaxies in the universe.”

http://www.physorg.com/printnews.php?newsid=6850

Source: Hebrew University of Jerusalem

 

[ramonmercado]

Meteorites Offer Glimpse Of The Early Earth

Meteorites Offer Glimpse Of The Early Earth, Say Purdue Scientists

Purdue University's Michael E. Lipschutz analyzed enstatite chondrite meteorites in a recent study of the materials near Earth at the dawn of the solar system about 4.5 billion years ago. Data from the study may offer clues into the conditions under which the Earth formed, evidence of which no longer exists in terrestrial stone. See larger photo. Credit: NASA.
by Charles T. Boutin
West Lafayette IN (SPX) Sep 29, 2005
Important clues to the environment in which the early Earth formed may be emerging from Purdue University scientists' recent study of a particular class of meteorites.
By examining the chemistry of 29 chunks of rock that formed billions of years ago, probably in close proximity to our planet, two Purdue researchers, Michael E. Lipschutz and Ming-Sheng Wang, have clarified our understanding of the conditions present in the vicinity of the ancient Earth's orbit.

Because direct evidence for these conditions is lacking in terrestrial samples, the scientists believe that the composition of these so-called enstatite chondrite (EC) meteorites could offer a window into the planet's distant past.

"What happened to these rocks most likely happened to the Earth in its early stages - with one great exception," said Lipschutz, a professor of chemistry in Purdue's College of Science.

"Shortly after the early Earth formed, an object the size of Mars smashed into it, and the heat from the cataclysm irrevocably altered the geochemical makeup of our entire planet. These EC meteorites, however, are likely formed of matter similar to that which formed the early Earth, but they were not involved in this great collision and so were not chemically altered. They might be the last remaining pristine bits of the material that became the planet beneath our feet."

The research appears in today's (Sept. 27) edition of a new journal, Environmental Chemistry, which solicited the paper. Lipschutz said the journal's editorial board includes F. Sherwood Rowland and Mario Molina, who received the Nobel prize for their discovery that Earth's protective ozone layer was threatened by human activity.

Lipschutz and Wang initially set out to increase our knowledge of EC meteorites, one of many different meteorite classes. Meteorites come from many different parts of the solar system, and a scientist can link one with its parent object by determining the different isotopes of oxygen in a meteorite's minerals.

Chunks of the moon, the Earth and EC meteorites, for example, have very similar isotopic "signatures," quite different from those of Mars and other objects formed in the asteroid belt. The variations occurred because different materials condensed in different regions of the disk of gas and dust that formed the sun and planets.

Bits of these materials orbit the sun, occasionally falling to earth as meteorites. But there is one place on our planet that meteorites accumulate and are preserved in a pristine fashion - the ice sheet of Antarctica.

"Over the millennia, many thousands of meteorites have struck the Antarctic ice sheet, which both preserves them and slowly concentrates them near mountains sticking through the ice, much as ocean waves wash pebbles to the shore," said Lipschutz.

"These stones have come from many different parts of the solar system and have given us a better picture of the overall properties of their parent objects."

By examining their mineralogy, scientists have determined that about 200 of these Antarctic stones are EC meteorites that formed from the same local batch of material as the Earth did more than 4.5 billion years ago.

But there is additional information that the chemistry of these Ecs can offer on the temperatures at which they formed. To obtain this information, however, required Lipschutz to analyze chemicals in the meteorites called volatiles - rare elements such as indium, thallium and cadmium.

"Volatiles in meteorites can give unique information on their temperature histories, but only 14 of them had ever been analyzed for these elements," Lipschutz said. "Naturally, we want to know the story behind the formation of objects in our own neighborhood, so we set out to increase that number."

In this study, the researchers gathered samples taken from another 15 EC meteorites that had, for the most part, landed in Antarctica tens of thousands of years ago. Using a unique method involving bombardment of the samples with neutrons, chemically separating the radioactive species and counting them, the researchers were able to determine the amounts of 15 volatiles that together offered clues to each rock's heating history.

"Volatiles can act like thermometers," Lipschutz said. "They can tell you whether the temperature was high or low when the rock formed. We tested two different kinds of Ecs, and the oldest, most primitive examples of each kind had very similar volatile contents - which means their temperature at formation was similar. These rocks have essentially recorded the temperature at which the early Earth formed, and we now know that this was much lower than 500 degrees Celsius."

The two different kinds of EC meteorites, known as Els and Ehs, were found in the Purdue study to have condensed at low temperatures like the Earth. However, the two groups are controversial because scientists have not been able to agree on whether they originated from a single parent object or two different ones. Unfortunately, Lipschutz said, the data from the 29 Ecs they analyzed were insufficient to settle the issue.

"There are still quite a few unanswered questions about the earliest periods of the Earth's history, and this study only provides one piece of the puzzle," he said. "But aspects of this study also show that Ecs differ substantially from other meteorite types that came from much farther out in the disk, in the region of the asteroid belt."

For Lipschutz, who had an asteroid named for him on his 50th birthday in honor of his many studies of meteorites, their parent bodies and the early history of the solar system, deeper answers may lie farther away than Antarctica.

"If we understand how our solar system formed, we might be better able to understand the processes at work in other solar systems, which we are just beginning to discover," he said. "Probing the asteroid belt could give us clues to these processes."


http://www.spacedaily.com/news/meteor-05f.html

 

[KeyserXSoze]

Source

'Planet Xena' has a sidekick: Gabrielle
Scientists find moon circling 'planet'

LOS ANGELES, California (AP) -- The astronomers who claim to have discovered the 10th planet in the Earth's solar system have made another intriguing announcement: it has a moon.

While observing the new, so-called planet from Hawaii last month, a team of astronomers led by Michael Brown of the California Institute of Technology spotted a faint object trailing next to it. Because it was moving, astronomers ruled it was a moon and not a background star, which is stationary.

The moon discovery is important because it can help scientists determine the new planet's mass. In July, Brown announced the discovery of an icy, rocky object larger than Pluto in the Kuiper Belt, a disc of icy bodies beyond Neptune. Brown labeled the object a planet and nicknamed it Xena after the lead character in the former TV series "Xena: Warrior Princess."

By determining the moon's distance and orbit around Xena, scientists can calculate how heavy Xena is. For example, the faster a moon goes around a planet, the more massive a planet is.

But the newly discovered moon, nicknamed Gabrielle after Xena's faithful traveling sidekick in the TV series, likely will not quell the debate over what exactly is a planet and whether Pluto should keep its status. The problem is there is no official definition for a planet and setting standards like size limits potentially invites other objects to take the "planet" label.

Possessing a moon is not a criteria of planethood since Mercury and Venus are moonless planets. Brown said he expected to find a moon orbiting Xena because many Kuiper Belt objects are paired with moons.

The moon is about 155 miles wide and 60 times fainter than Xena, the farthest-known object in the solar system. It is currently 9 billion miles away from the sun, or about three times Pluto's current distance from the sun.

Scientists believe Xena's moon was formed when Kuiper Belt objects collided with one another. The Earth's moon formed in a similar way when Earth crashed into an object the size of Mars.

The moon was first spotted by a 10-meter telescope at the W.M. Keck Observatory in Hawaii on September 10. Scientists expect to learn more about the moon's composition during further observations with the Hubble Space Telescope in November.

Brown planned to submit a paper describing the moon discovery to the Astrophysical Journal next week.

The International Astronomical Union, a group of scientists responsible for naming planets, is deciding on formal names for Xena and Gabrielle.

 

[rynner2]

Quick, it starts soon!

Moon moves to make dazzling ring

A dark shadow is about to be thrown over much of Europe, Africa, Asia and the Middle East in an annular eclipse.
Monday will see the Moon sweep across the face of the Sun, with a partial eclipse starting in London at 0848BST.

An annular eclipse is less spectacular than a total solar eclipse because the sky does not go completely black.

Some skywatchers should see a blazing ring of fire surround the Moon's disc. In Aberdeen 44% of the Sun will be covered, compared to 64% in Plymouth.

Once again, though, astronomers are urging those without the proper viewing equipment not to look directly at the Sun with the naked eye; blindness could result.

In and out

In the UK, only a partial eclipse will be visible; the Moon will be seen to take a large chunk out of the Sun.

Depending on where one is standing, between 44% (Aberdeen) and 64% (Plymouth) of the Sun will be covered, according to the Society for Popular Astronomy.

In London, this partial eclipse starts at 08:48BST and ends at 11:18BST.

Not every eclipse can be total. The Moon's orbit around the Earth is not perfectly round; the satellite's distance from the planet varies from about 356,000 to 407,000km (221,000 to 253,000 miles).

This difference makes the Moon's apparent size in our sky fluctuate by about 13%.

If the Moon happens to eclipse the Sun on the near side of its orbit, it totally blocks out the star (a total eclipse).

But if the Moon eclipses the Sun on the far side of its orbit, the satellite will not completely obscure the star's disc - and a ring or annulus of sunlight is seen.

The effect is to throw an "antumbra" or "negative shadow" on the Earth's surface as the Moon moves across the face of the Sun. It is the track of this antumbra that is referred to as the "path of annularity".

And although the daylight will significantly dim for those in this path, a substantial portion of sunlight will still be visible and potentially highly dangerous to anyone tempted to squint at the eclipse.

Unless you have access to a telescope or binoculars equipped with proper solar filters, or approved eclipse glasses, the advice is to use a pin-hole camera technique to project the eclipsing Moon and Sun on to a piece of paper.

A good option will be to watch the event on one of several websites geared up to stream it.

The path of annularity across the Earth's surface begins out in the North Atlantic at 08:41GMT. Its snake-like route then takes it across the Iberian Peninsula, passing Madrid at 08:56 GMT; crossing the western Mediterranean and moving on to the African continent, and arriving at Algiers a 09:05GMT.

From there, the path follows a south-eastern route, through southern Tunisia and central Libya.

After briefly skirting northern Chad, the antumbra sweeps across central Sudan where the period of greatest eclipse will be experienced at 10:31GMT.

The 'beads'

The annular duration here will last four minutes and 31 seconds, according to the US space agency's "Mr Eclipse", Fred Espenak, who has become an oracle for eclipse calculations.

The path then heads along the southern Sudanese-Ethiopian border before entering Kenya and Somalia. It leaves land at 11:30GMT and only a ship in the Indian Ocean could experience the end of the eclipse at 12:22GMT.

Those lucky enough to be in the path of annularity and with clear skies should look for the "beads" or "gems" that skirt the fiery ring.

These are caused by sunlight streaming through valleys and past mountains on the Moon's surface.

This is the fourth annular eclipse of the 21st century. The next total solar eclipse is on 29 March, 2006. It will traverse equatorial West Africa, the Sahara, the western Mediterranean, Turkey and Russia.

If you are planning on taking pictures of the eclipse you can send them to us at [email protected]

http://news.bbc.co.uk/1/hi/sci/tech/4299074.stm

 

[Rubyait]

Cosmic expansion is not to blame for expanding waistlines

"YOUR waistline may be spreading but you can't blame it on the expansion of the universe." So says Richard Price, a physicist at the University of Texas at Brownsville, who has worked out that while some objects are stretched by cosmological expansion, others are not.

Cosmologists have long accepted that the universe is expanding, causing galaxies to spread apart like raisins in a rising loaf of bread, as the space between them stretches. But while Price was teaching a summer course, a question from a high-school student floored him. "He asked me if, as space expands, we all get bigger too," says Price. "I knew the standard answer was 'no', but I couldn't explain why not. And when I consulted my colleagues, neither could they."

Since atoms are made up mostly of empty space, with electrons "orbiting" the nucleus at distances typically many hundreds of times its diameter, it seemed reasonable to ask whether the electrons would be dragged away from the nucleus by the stretching of space. Price decided to examine the simplest system, that of a hydrogen atom, with one negative electron orbiting a positive proton. He found if the force involved - electromagnetic in the case of atoms - binding the system together is stronger than a certain critical value, the system will be entirely unaffected by the cosmological expansion (www.arxiv.org/abs/gr-qc/0508052).

"This means that the solar system - which is quite tightly bound by gravity - doesn't expand. Your desk doesn't expand. Your dog doesn't expand," says Price. "But clusters of galaxies, which are only loosely bound by gravity, will feel this effect."

Price also found that the atoms never experience just a little stretching - either they must totally ignore the expansion of the universe or they will be completely torn apart. "This all-or-nothing effect is a startling result," says Roy Maartens, a cosmologist at the University of Portsmouth in the UK. "This question has been knocking around since the 1930s, but nobody has found this before."

Andrew Jaffe, an astrophysicist at Imperial College London in the UK believes the effect becomes interesting in so-called "big rip" cosmologies in which the universe is not only expanding, but the expansion is accelerating.

"Price's calculation still holds in this case, but you start to see the opposite effect," says Jaffe. The expansion of the universe accelerates drastically. First it overpowers gravity, ripping apart solar systems, and next the electromagnetic forces are overwhelmed. "The planets are torn apart, and then you and me, and finally the atoms that make us up are destroyed," says Jaffe. "That's not a particularly fun way to end."

http://www.newscientist.com/article.ns?id=dn8082