Universe Today

We can't look at the beautiful structure of the Milky Way because we're stuck inside it. But we can do the next best thing and look at a virtual twin of our galaxy: Triangulum galaxy M33. Although M33 looks like the Milky Way, it's actually much smaller. We hold 200 billion stars, while M33 only has 10-40 billion stars. The Andromeda galaxy is even bigger, holding more than a trillion stars. This photograph was taken by the new Megacam instrument attached to the MMT 6.5 metre telescope.
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A team of scientists has set out to visit an unusual hot spring on Ellesmere Island near the North Pole. This spring spews out sulphur-rich water that has become an ecosystem for bacteria in an otherwise lifeless ice field. The researchers are hoping to understand the underground structure of the spring, and locate the source of the sulphur. An environment like this could help scientists search for signs of life in other hotspots in the Solar System, such as Mars, Europa, or Enceladus.
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NASA researchers fortunate enough to be recording the Moon through a 10" telescope equipped with a video camera when they saw a meteoroid strike. The spacerock was only 25 cm (10 inches) wide, but it released 17 billion joules of kinetic energy; the same as 4 tons of TNT. The resulting flash was quick, only lasting 4/10ths of a second, but it was powerful enough to carve out a crater 14 metres (46 feet) wide.
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Hi everyone, I just wanted to let you all know that I'm aware that images aren't showing up in the RSS feed or the email newsletter. I've changed my publishing system to a program called Wordpress. It's a huge timesaver, but I'm still working to make it match all the features of the old design. It's going to be a few more days before I've got the images showing up. After I get that working, I'm going to bring my entire archive over, so that will be accessible again.
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On the morning of September 8, 2004, NASA scientists were elated. Their Genesis spacecraft had traveled 32 million kilometers (20 million miles), and was loaded up with precious samples of the solar wind and interstellar particles. But as the spacecraft hurtled through the Earth's atmosphere, it quickly became clear something was very wrong. Instead of floating gently down to Earth on its parachutes, Genesis cratered into the ground at high speed, and its fragile cargo suffered devastating damage. What went wrong? A special Mishap Board released their findings today.
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The space shuttle came into being with the promise of delivering on many hopes and dreams of today's space farers. As a steady workhorse or a novel research platform, it was to be a high flyer and smooth glider. Columbia was the first of these shuttles to venture into the domains of outer space. In spectacular fashion, it proved the designers' estimates and made low earth orbit a ready destination. Ben Evans, in his book Space Shuttle Columbia - Her Missions and Crews, recalls the numerous contributions which this single shuttle made during its many years of satisfying service.
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Greetings, fellow SkyWatchers! This week will be an exciting one as we return the the galaxy hunt and view the cosmos through the eyes of Pioneer. The excitement heats up as the Ophiuchid meteor shower comes along and Mars mixes it up with the Beehive. Still not enough? Then hang on as the June Lyrids streak across the night and Saturn and Mars team up to join Mercury! It's going to be one great week to enjoy the night, because…

Here's what's up!
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The newest image released from the Hubble Space Telescope shows the turbulent region where two galaxies are merging together. The galactic collision is known as Arp 220, and it's one of the nearest, brightest examples of this in the sky. Hubble's keen vision has located more than 200 massive star clusters, the largest of which is twice as big as anything we have in the Milky Way. Arp 220 should continue producing new start clusters until it runs out of gas in about 40 million years.
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Around midnight this time of year it's possible to witness the fires that smolder at our galaxy's core. Northern star gazers can see this by looking to the south, just above the horizon. Folks in the southern hemisphere should look closer overhead. Regardless, it's a view that should not be missed, if possible. This picture offers a tantalizing close-up that's part of the scene.
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This close up view of Saturn shows an unusual feature in its atmosphere. It appears as if part of one belt is crossing over into another. Another possibility is that it's just an illusion created by different layers of clouds. Cassini took this photograph on May 12, 2006 at a distance of approximately 2.9 million kilometers (1.8 million miles) from Saturn.
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NASA's newly launched CALIPSO Earth observation satellite began its scientific observations last week. The satellite is designed to help scientists understand what effect cloud reflectivity and aerosol particles are having on the planet's climate. CALIPSO is part of a satellite formation called the A-Train; several satellites in the same orbit which can analyze the same spot on Earth, one after the other.
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An international team of astronomers have discovered a massive gas ball hurtling through a distant galaxy cluster. This ball of gas is traveling more than 750 km/second (466 miles/second) through galaxy cluster Abell 3266. The enormous speed and pressure has heated the gas up to the point that it blazes in the X-ray spectrum. The discovery was made using ESA's XMM-Newton X-ray satellite.
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A plume of water ice is seen streaming off the southern pole of Saturn's moon Enceladus in this photograph. Cassini used very long exposure to capture the wispy stream of vapour, so everything else in the image is overexposed. Cassini took the photograph on May 4, 2006 at a distance of approximately 2.1 million kilometers (1.3 million miles) from Enceladus.
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This image, taken by ESA's Mars Express spacecraft, shows Apollinaris Patera, an ancient volcano caldera near Gusev Crater on Mars. The massive volcano measures 180 by 280 kilometres (112 by 174 miles) at its base and rises 5 km (3 miles) above the surrounding terrain. The bluish-tinted haze are thin clouds above the rim of the caldera.
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One of the biggest brightest clusters of stars in the sky is 47 Tucanae, located in the southern constellation of the Toucan. Located about 16,000 light years away, this globular cluster contains a million times the mass of our Sun, and measures 120 light years across. The stars in the cluster are so dense, they average only 1/10th a light year apart; approximately the size of the Solar System. This photograph was taken using the European Southern Observatory's Very Large Telescope.
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A pair of astronomers from the US and Italy have discovered a stream of stars moving through the sky at 230 km/second (500,000 mph). The stream has been found to extend 30,000 light years across the sky, but it could extend even further. The discoverers believe the stream is all the remains of a gigantic star cluster that was torn apart by the Milky Way's gravity. If correct, there could be hundreds more of these streams circling our galaxy.
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In addition to the Moon, the Earth also has a collection of co-orbital satellites. These are really nothing more than asteroids briefly captured by the Earth's gravity. Instead of orbiting the Earth, they take corkscrew paths around our planet, eventually escaping back into the Solar System. One asteroid, 2003 YN107, has been traveling with us since 1999, and now it's about to depart, building up enough speed to escape the Earth's gravity.
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This photograph shows Titan partly obscured behind Saturn and its rings. The image was taken from above the ringplane, and shows the side of the planet unlit by the Sun. Cassini captured this view on May 10, 2006 at a distance of approximately 2.9 million kilometers (1.8 million miles) from Saturn.
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As early as 700 million years after the Big Bang, galaxies were already filled with cosmic dust. But where did it come from? There are two known sources of dust: old stars and supernovae. Astronomers studied nearby supernovae SN 2003gd using the Spitzer space telescope, and found that it had produced tremendous amounts of dust. Since there were many supernovae in the early Universe, they could be the source of all this dust.
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Approximately 2.3 billion years ago, bacterial life had generated enough oxygen to make the air breathable for larger creatures. Unfortunately, this was also a stage when our planet went through one of its "Snowball Earth" phases, when the entire planet was encased in kilometer-thick snow and ice. Scientists have found evidence that multi-celled eukaryotes - our distant ancestors - were thriving on Earth, before and after the big chill. While most of the planet was covered, there were probably pockets that were ice free, where islands of life could survive.
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The Hubble Space Telescope captured this magnificent view of disk galaxy NGC 5866, seen nearly edge on from our vantage point. The galaxy's dark dust lane is clearly visible, and it appears to be slightly warped, compared to the disk of starlight. This indicates that it probably brushed past another galaxy in the distant past. NGC 5866 is located in the constellation Draco, approximately 44 million light-years away; it's similar in mass to the Milky Way, but only two-thirds the diameter.
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Although our Solar System only contains a "regular Earth", astronomers predict that other systems could contain "super Earths"; rocky planets with several times the mass of our planet. A new theory predicts that these planets should be most commonly found orbiting red dwarf stars. As red dwarf stars have less mass, they're unable to hang onto the lighter gas that go onto form gas giants. The remaining heavier elements have time to form very massive terrestrial planets.
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Astronomers have discovered a solar system with an unusually high amount of carbon; it could be at the stage where the rocky planets are forming. The system, called Beta Pictoris, is located 63 light-years from Earth and has a central star with twice the mass of our Sun. NASA's FUSE (Far Ultraviolet Spectroscopic Explorer) and Hubble observed that gas around the star matches the composition of our own Solar System quite well. The stars intense radiation should be driving this gas away, but ionized carbon atoms are acting as a brake to keep it contained.
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Meteorologists and scientists have a new tool at their disposal; NASA's new CloudSat satellite, which is capable of building 3-D images of clouds. CloudSat launched on April 28 from Vandenberg Air Force Base with two other satellites. After several weeks of testing, mission managers tested its Cloud-Profiling Radar system in May. Its first image was a slice of atmosphere above the North Sea in the Atlantic Ocean. CloudSat's radar system is 1,000 times more powerful than typical weather radar.
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Magnetic field lines at the surface of Tau Scorpii. Image credit: M. M. Jardine/J. F. Donati. Click to enlarge
Our Sun can send out its share of solar flares and coronal mass ejections, but compared to other stars, it's relatively calm. One example is tau Scorpii, 5-6 times larger than the Sun and visible with the unaided eye. Astronomers have discovered that it has a complex network of magnetic field lines which channel its solar winds into thin arcs. The high points of these arcs blaze brightly in the x-ray spectrum.

An international team of astronomers has discovered that the naked-eye star, tau Scorpii, unexpectedly hosts a complex network of magnetic field lines over its surface.

Our Sun has its explosive flares and spots and high speed wind, but it is a placid star compared to some. Stars that are much more massive live fast and die young, with blue-white, intensely hot surfaces that emit energy at a rate millions of times greater than that of the Sun. These stars are so bright that their light alone propels outflowing stellar winds - up to a billion times stronger than the solar wind - at speeds of up to 30,000 km/s, or one per cent of the speed of light.

Tau Scorpii has been known for some time to emit X-rays at an unusually high rate and to rotate more slowly than most otherwise similar stars. The newly discovered magnetic field, presumably a relic from the star's formation stage, goes some way to explaining both characteristics, although the mechanism by which the magnetic field slowed down tau Scorpii's rotation so strongly remains mysterious.

These results will be published in the Monthly Notices of the Royal Astronomical Society.

The processes by which hot, massive stars expel their surface layers through their strong outflowing winds have a major impact on a star's long-term fate. The cast-off material can also interact with other nearby stars, contribute matter and energy to the surrounding interstellar medium, and even induce bursts of new star formation. Hot massive stars are thus key actors in the life of a galaxy.

One such hot star is tau Scorpii, whose intrinsic brightness is so great that it is easily visible with the naked eye, despite its distance of over 400 light-years. Weighing as much as 15 Suns, tau Scorpii is 5 to 6 times bigger and hotter than our own star. Such massive stars are relatively few in number compared to stars like the Sun, and tau Scorpii is actually one of our closest massive neighbours.

Massive stars are thought to emit X-rays because of supersonic shocks occurring within their outflowing winds. However, tau Scorpii is an unusually strong X-ray source compared to stars which are otherwise similar.

The reason for this enhanced activity was a puzzle until the present discovery, which revealed that the star hosts a complex network of magnetic field lines over its surface (see image). According to the discovery team, this field is most probably a relic from the star's formation stage.

The most interesting aspect, though, is how the field interacts with the wind, forcing it to flow along magnetic field lines, like beads along wires. Wind streams along 'open' magnetic field lines (shown in blue) freely escape the star, something that wind streams in magnetic 'arcades' (shown in white) cannot achieve. The result is that, within each magnetic arcade, wind flows from both footprints collide with each other at the loop summits, producing tremendously energetic shocks and turning the wind material into blobs of million-degree, X-ray emitting plasma tied to the magnetic loops.

This model provides a natural explanation of why tau Scorpii is such an intense X-ray emitter. However, it is not yet clear how the magnetic field succeeded in slowing down the rotation rate of the star to less than one-tenth that of otherwise similar, non-magnetic, massive stars.

Sun-like stars can be slowed down through their magnetic wind, just as ice-skaters are spun down when outstretching their arms. Tau Scorpii does not, however, lose material fast enough to have its rotation modified within its very short lifetime of a few million years.

The researchers discovered and examined the magnetic field of the star by looking at the tiny, very specific polarisation signals that magnetic fields induce in the light of magnetic stars. To do this, they used ESPaDOnS, by far the most powerful instrument in the world for carrying out this kind of research. This new instrument, currently attached to the Canada-France-Hawaii Telescope on Hawaii, was specially designed at the Observatoire Midi-Pyrenees in France for observing and studying magnetic fields in stars other than the Sun.

Original Source: AAS News Release

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