July 19, 2006, 9:51 PM CT

Black Holes At The Center Of Galaxies?

Bubbles of dark matter could be masquerading as supermassive black holes at the centres of galaxies. If so, they could explain the puzzling pattern of X-ray emissions from the heart of the Milky Way.

Cosmologists know that most galaxies host a compact, supermassive object at their centre and they believe these must be black holes. Such a black hole is thought to be responsible for the X-ray flares coming from the middle of our galaxy, which would be caused by the black hole devouring surrounding matter. But recent observations show that these flares fire roughly every 20 minutes - a regularity that is hard to explain in terms of the behaviour of a black hole.

Now Anatoly Svidzinsky, a physicist at Texas A&M University in College Station, Texas, thinks that hypothetical particles called axions could solve the mystery. Axions have very little mass and no electric charge, and they barely interact with other particles. They were originally proposed to fix a problem with the strong force in particle physics, but have more recently been considered as possible candidates for dark matter, the unseen stuff thought to make up nearly 90 per cent of a galaxy's mass.

In the 1990s, computer simulations of clouds of dark matter made of axions showed that giant bubbles of these particles would burst out from the clouds. Svidzinsky thinks that such bubbles exist at the centre of galaxies. His model shows that the axion bubbles would expand and contract with a period of 20 minutes - matching the period of infrared and X-ray flares from Sagittarius A*, the location of the supermassive compact object at the centre of our galaxy. The model predicts that stable axion bubbles would weigh between about 1 million and 2.5 billion times the mass of the sun - exactly the mass range observed for compact objects at the centres of galaxies (www.arxiv.org/ astro-ph/0607179).........

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July 17, 2006, 8:20 PM CT

Next-generation High-altitude Airships

"Paint-on" antennas, designed to establish new high-altitude communications and surveillance platforms, successfully transmitted voice and data links as well as teleconferencing capabilities during test flights in the Nevada desert June 21 on board an SA-60 spherical airship.

RTI International and its research partners at Unitech, Applied EM, the International Communications Group, and TechSphere Systems International, a wholly owned subsidiary of Cyber Defense Systems, successfully tested the antennas from several positions on the airship. The experiment provided the first opportunity to test and evaluate the electrical, electromagnetic and mechanical properties of the "paint-on" antenna technology during an actual flight.

"The successful airship test flights demonstrate exciting possibilities for 'paint-on' antenna technologies," said David Myers, vice president of RTI's Engineering and Technology Unit. "This new technology can be used to assist with hurricane disaster relief, provide enhanced security of ports and borders, perform science observation missions and improve military communications".

High-altitude airships can be used for both defense and homeland security purposes including surveillance of battlefields and domestic borders and ports. The airships are intended to serve as economical station-keeping communications and/or ground-sensing platforms that will augment both ground-based and more expensive satellite systems. The airships will operate well above commercial air traffic and the jet stream and beyond the range of most ground-to-air missiles.........

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June 28, 2006, 11:47 PM CT

The Hooked Galaxy

Because of the importance of exploding stars, and especially of supernovae of Type Ia [1], for cosmological studies (e.g. relating to claims of an accelerated cosmic expansion and the existence of a new, unknown, constituent of the universe - the so called 'Dark Energy'), they are a preferred target of study for astronomers. Thus, on several occasions, they pointed ESO's Very Large Telescope (VLT) towards a region of the sky that portrays a trio of amazing galaxies.

MCG-01-39-003 (bottom right) is a peculiar spiral galaxy, with a telephone number name, that presents a hook at one side, most probably due to the interaction with its neighbour, the spiral galaxy NGC 5917 (upper right). In fact, further enhancement of the image reveals that matter is pulled off MCG-01-39-003 by NGC 5917. Both these galaxies are located at similar distances, about 87 million light-years away, towards the constellation of Libra (The Balance).

NGC 5917 (also known as Arp 254 and MCG-01-39-002) is about 750 times fainter than can be seen by the unaided eye and is about 40,000 light-years across. It was discovered in 1835 by William Herschel, who strangely enough, seems to have missed its hooked companion, only 2.5 times fainter.

As seen at the bottom left of this exceptional VLT image, a still fainter and nameless, but intricately beautiful, barred spiral galaxy looks from a distance the entangled pair, while a number of 'island universes' perform a cosmic dance in the background.........

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June 28, 2006, 0:12 AM CT

Kidney Stone Prevention In Astronauts

As the space shuttle Discovery prepares to launch on July 1, researchers at the University of Minnesota have identified a way for astronauts to reduce their risk of developing kidney stones while in space.

Astronauts lose calcium in their bones and strength in their muscles while in space because of the zero-gravity environment. This calcium can end up in their kidneys, putting them at risk for developing kidney stones.

At least 14 American crew members have developed kidney stones in the last 5 years, and as missions become longer, the number is likely to grow. While astronauts have exercised in space to attempt to combat bone loss, the lack of gravity makes it difficult to achieve enough resistance to maintain their pre-flight fitness levels.

"This becomes a real health concern, as the time astronauts spend in space and living in the space station is extended," said Manoj Monga, M.D., professor of urologic surgery and lead investigator. The study would be published in the July 2006 print issue of the Journal of Urology and is available online now.

Kidney stones are mineral deposits in the kidneys that can travel through the urinary tract, causing intense pain. One of the most common types of kidney stones is caused by the buildup of calcium oxalate.........

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June 21, 2006, 11:25 PM CT

Saturnian Moon Ballet

The cold, icy orbs of the Saturn system come to life in a slew of new movie clips showing the ringed planet's moons in motion.

In addition to their drama and visual interest, researchers use these movies to refine their understanding of the orbits of Saturn's moons. Engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., use the same images, and the orbital positions of the moons, to help them navigate the Cassini spacecraft, which is nearing the halfway mark of its four-year tour.

Pictures capturing several moons in one frame are often strikingly beautiful, particularly when deliberately imaged in red, green and blue spectral filters, which allow researchers to create a color photo. One recent color image shows two of Saturn's most fascinating moons, icy-white Enceladus and orange, haze-enshrouded Titan.

Ironically, what these two moons hold in common gives rise to their starkly contrasting colors. Both bodies are, to varying degrees, geologically active. For Enceladus, its southern polar vents emit a spray of icy particles that coats the small moon, giving it a clean, white veneer. On Titan, as-yet-undefined processes are supplying the atmosphere with methane and other chemicals that are broken down by sunlight, creating the thick yellow-orange haze that suffuses the atmosphere and, over geologic time, falls and coats the surface.........

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June 18, 2006, 12:01 AM CT

Mini-planet Systems Get Stranger

Mini planetary systems may orbit cosmic objects that are 100 times smaller than our Sun, research suggests.

Discs of gas and dust, the ingredients needed to create such systems, have been seen circling these relatively small objects, dubbed "planemos".

If the discs were capable of evolving larger aggregations of material, it would blur the definition of the word "planet", scientists said.

The work was presented at the American Astronomical Society meeting in Canada.

Cosmic newborns

The study is based on observations from European Southern Observatory (ESO) telescopes. It looked at many recently identified planemos (an unofficial term sometimes used to describe planetary mass objects).

Located about 450 light-years away in a star-forming region, four of the objects are just a few million years old, making them cosmic "newborns". They have masses between five and 15 times that of Jupiter.........

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June 5, 2006, 9:01 PM CT

Hundreds Of Young, Distant Galaxy Clusters

Astronomers have found the largest number of the most distant, youngest galaxy clusters yet, a feat that will help them observe the developing universe when it was less than half its current age and still in its formative stages.

The team of astronomers from the University of Florida, NASA's Jet Propulsion Laboratory and the Lawrence Livermore National Laboratory has found nearly 300 new galaxy clusters and groups, including nearly 100 at distances of eight to 10 billion light years. The new sample, a six-fold increase in the number of known clusters and groups at such extreme distances, will allow astronomers to study very young galaxies two-thirds of the way back to when the universe is believed to have originated in the Big Bang.

The team will present its findings today in Calgary, Canada, at the American Astronomical Society's biannual meeting.

Anthony Gonzalez, an assistant professor of astronomy at UF and one of the team of astronomers who made the discovery, likened the view of the clusters to a glimpse at the Los Angeles basin when it was still home only to a collection of dusty, small towns. By knowing what the clusters looked like eight to 10 billion years ago, the astronomers will have a better idea of where and when the first stars and galaxies formed and how they grew and changed over the universe's full 13.7 billion- year lifespan.........

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May 23, 2006, 8:59 PM CT

Milky Way Companions

The Sloan Digital Sky Survey (SDSS-II) announced recently the discoveries of two new, very faint companion galaxies to the Milky Way.

The first was found in the direction of the constellation Canes Venatici (the Hunting Dog) by SDSS-II researcher Daniel Zucker at Cambridge University (UK). His colleague Vasily Belokurov discovered the second in the constellation Bootes (the Herdsman).

"I was poring over the survey's map of distant stars in the Northern Galactic sky - what we call a Field of Streams -- and noticed an overdensity in Canes Venatici," Zucker explained. "Looking further, it proved to be a previously unknown dwarf galaxy. It's about 640,000 light years (200 kiloparsecs) from the Sun. This makes it one of the most remote of the Milky Way's companion galaxies".

Zucker emailed Belokurov with the news, and, just as discoveries often build upon one another, Belokurov excitedly emailed back a few hours later with the discovery of a new, even fainter dwarf galaxy. The new galaxy in Bootes, which Belokurov called 'Boo,' shows a distorted structure that suggests it is being disrupted by the Milky Way's gravitational tides. "Something really bashed Boo about," said Belokurov.

Eventhough the dwarf galaxies are in our own cosmic backyard, they are hard to discover because they are so dim. In fact, the new galaxy in Bootes is the faintest galaxy so far discovered, with a total luminosity of only about 100,000 Suns. But because of its distance (640,000 light years) it appears almost invisible to most telescopes. The prior dimness record holder was discovered last year in Ursa Major using SDSS-II data.........

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May 23, 2006, 8:54 PM CT

Largest-ever 3D Map of a Million Galaxies

An international team of astronomers has released new results on the Cosmos, based on the largest map of the heavens ever produced.

This massive atlas emphatically confirmed recent findings that the Universe is full of 'dark energy', a mysterious substance that makes up three-quarters of our Universe, together with 'dark matter' which accounts for most of the remaining quarter. Understanding this composition is now one of the most important problems encountered the whole of science.

"We now have a precise view of what makes up our Universe, but little idea as to why," said Prof. Ofer Lahav, a member of the international team and the Head of the Astrophysics Group at University College London. "It is intriguing that the ordinary matter our bodies are made of and that we experience in everyday life only accounts for a few percent of the total cosmic budget."

Our Universe contains billions of galaxies of all shapes and sizes. In recent years astronomers have used increasingly large surveys to map out the positions of these galaxies, stepping their way out into the Cosmos.

The new cosmic map unveiled today is the largest to date -- a three-dimensional atlas of over a million galaxies spread over a distance of more than 5 billion light years. The findings confirm that we live in a Universe filled with mysterious dark matter and dark energy.........

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May 23, 2006, 8:51 PM CT

Multiple Galaxy Mergers Continue in Milky Way

A new map of stars in the Milky Way Galaxy, constructed with data from the Sloan Digital Sky Survey (SDSS-II), reveals a night sky criss-crossed with streams of stars, left behind by satellite galaxies and star clusters spiraling to their deaths.

Analyzing five years of data spanning nearly one-quarter of the sky, Cambridge University (UK) scientists Vasily Belokurov and Daniel Zucker created a dramatic new image of the outer Milky Way, using stellar colors eliminating the redder, nearby stars that would otherwise swamp the view of background structures. They found so a number of trails of stars in their high contrast image that they named the area the "Field of Streams".

Satellite galaxies orbiting the Milky Way are literally ripped apart by the tidal forces of our galaxy. As these satellites sink in gravitational quicksand, their stars are torn from them in giant streams that trace their orbital paths -- just like meteor streams lie along the paths of defunct comets in the Solar system.

Dominating the Field of Streams image is the enormous, arching stream of the Sagittarius dwarf galaxy. The Sagittarius dwarf was discovered more than a decade ago and other scientists have previously mapped its long tidal stream in other regions of the sky.

But the new SDSS-II data had a remarkable surprise in store.........

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