This photograph of galaxy NGC 908 was taken with the European Southern Observatory’s Very Large Telescope. This spiral galaxy was first discovered in 1786 by William Herschel, and is considered a starburst galaxy. Clusters of young, massive stars pepper its spiral arms indicating regions of furious star formation. NGC 908 must have had a recent encounter with another galaxy; the gravitational interaction between the galaxies caused gas clouds to collapse, igniting star formation.
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The Search for Hidden Black Holes
Look into the sky with X-ray instruments, and you’ll see a background radiation in all directions. Astronomers think these X-rays are produced by the supermassive black holes at the centres of most galaxies. But astronomers can’t find these black holes, which should be bright in the most energetic range of the electromagnetic spectrum. Maybe they’re hiding; shrouded in thick clouds of gas and dust. Or maybe something else is generating all the X-ray background radiation.
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New View on Pulsars
Pulsars are the rapidly spinning corpses of massive stars. And although they were discovered nearly 40 years ago, they still hold many mysteries. One such mystery: why do pulsars have million-degree hotspots around their poles? New data from ESA’s XMM-Newton X-Ray observatory have cast doubt on the theory that charged particles are colliding with the pulsar’s surface at its poles. XMM-Newton failed to see the X-ray emissions in several old pulsars that should have been very bright if particles were continuously colliding.
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Astrophoto: Centaurus A by Johannes Schedler
Natural disasters are, unfortunately, something that we must contend with. For example, a flash flood can plunge towns into unexpected chaos, a hurricane strike can suddenly devastate an entire region and science has found evidence of an ancient asteroid impact that curtailed the rein of the dinosaurs by affecting climate across our planet. But these kind of events occur on an even greater scale – natural circumstances can lead to catastrophes that engulf whole galaxies such as seen in this picture.
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Huygens Data Used to Measure Titan’s Pebbles
When ESA’s Huygens probe landed on the surface of Saturn’s moon Titan last year, it continued to transmit data for 71 minutes. The signal relayed through Cassini had a strange fluctuation in power as the angle between the lander and spacecraft changed. Researchers were able to reproduce this power oscillation when they realized that the signal was bouncing off of pebbles on Titan’s surface. They were able calculate that the surface around Huygens is mostly flat, but littered with 5-10 cm (2-4 inch) rocks.
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Evidence of Lakes on Titan
NASA’s Cassini spacecraft has found new evidence of hydrocarbon lakes in Titan’s northern latitudes. In a new set of images, the dark patches – thought to be liquid methane or ethane – seem to have channels leading in and out, like rivers. Under Cassini’s radar view, they’re completely black, which means they don’t reflect any radar signals back. This leads scientists to believe they’re very smooth, liquid surfaces.
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A New View of Quasars
Some of the brightest objects in the Universe are quasars. A mystery for decades, most astronomers now believe quasars are the bright centres of galaxies with actively feeding supermassive black holes. A team of researchers have found evidence that there might be something very different at the heart of these galaxies to cause quasars. Instead of black holes consuming matter, there could be objects with powerful magnetic fields that act like propellers, churning matter back into the galaxy.
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Podcast: Inevitable Supernova
Consider the dramatic binary system of RS Ophiuchi. A tiny white dwarf star, about the size of our Earth, is locked in orbit with a red giant star. A stream of material is flowing from the red giant to the white dwarf. Every 20 years or so, the accumulated material erupts as a nova explosion, brightening the star temporarily. But this is just a precursor to the inevitable cataclysm – when the white dwarf collapses under this stolen mass, and then explodes as a supernova. Dr. Jennifer Sokoloski has been studying RS Ophiuchi since it flared up earlier this year; she discusses what they’ve learned so far, and what’s to come.
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What’s Up this Week: July 24 – July 30, 2006
Greetings, fellow SkyWatchers! Welcome to a land of all sight and no sound… A land where shadow meets substance. Welcome to the “X” zone! Caught in a time warp? Not this week. Be sure to enjoy some of the best observing of the year as we head towards the center of our galaxy, walk on the lunar surface and chase shooting stars. So head out into the twilight, because….
Here’s what’s up!
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Earth-Sized Planets Could Be Nearby
Nearly all of the extrasolar planets discovered so far have been huge, Jupiter-sized and above. The question is: could smaller, Earth-sized planets last in the same star systems? Researchers created a simulation where tiny planets were put into the same system as larger planets to see if they could gather enough material to become as large as the Earth. They found that one nearby system – 55 Cancri – could have formed terrestrial planets, with substantial water in the habitable zone.
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