Earth’s Second Moon is About to Leave Us

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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Supernovae Generated the Universe’s Early Dust

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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Ancient Life Survived Snowball Earth

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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Hubble View of NGC 5866

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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How Super Earths Might Form

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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Large Amounts of Carbon Around a Distant Star

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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First Images From Cloudsat

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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Tau Scorpii’s Magnetic Fields Blaze X-Rays

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

Amazing Astrophotos in the Forum

I just wanted to draw your attention to the Astrophotography section of the Bad Astronomy/Universe Today forum. Members have been posting tons of amazing images every day; too many for me to feature in Universe Today. Here’s the catch, though. You have to be a member of the forum to see the photos. Membership is totally free, just register from this page.

And speaking of the forum, one of our members, parallaxicality, recently wrote up an article on Wikipedia that was recently featured as one of the best articles on the site. Read about the Definition of a Planet, and then give your congrats to parallaxicality.

Fraser Cain
Publisher
Universe Today

P.S. The American Astronomical Society is having its annual meeting in Calgary this year, and they’re generating enormous amounts of news. Universe Today is going to be pretty big for the next few days. Enjoy.