ESA’s Integral space observatory has spotted a blast of gamma rays from a suspected black hole in the Milky Way. the outburst occurred on September 17, 2006, and gradually built in brightness over the course of a few days before declining again. It’s this rise and fall of brightness, called a light curve, that allowed astronomers identify the source as a black hole. It’s likely that a disk of gas and material orbiting the black hole became unstable, and a portion of it collapsed, creating the outburst.
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What’s Up this Week: November 27 – December 3, 2006
Greetings, fellow SkyWatchers! Sister Selene is back en force, so why not take a few evenings to catch up on some lunar features? If you want to double your pleasure and double your fun – why not look at binary stars instead of just one! Time to dust off the telescope and head out into the night, because…
Here’s what’s up!
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Pan Clearing a Gap in Saturn’s Rings
If you want to understand what causes the gaps in Saturn’s rings, just look at this picture. The bright object in the middle of Saturn’s Encke gap is one of its moons: Pan. The tiny moon is only 26 km (16 miles) across, but its minor gravity can clear out the ring particles. Cassini took this image on October 27, 2006 when it was 385,000 km (239,000 miles) from Pan.
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Starburst Galaxy NGC 1313
This is an image of galaxy NGC 1313, taken with the FORS instrument at the ESO’s Very Large Telescope. It’s classified as a starburst galaxy, because of the dense regions of furious star formation. NGC 1313 is relatively close to the Milky Way, located only 15 million light-years away. To say it’s forming many new stars is an understatement; NGC 1313 has a rate of star formation 1000x faster than the Milky Way. Galaxies like this usually went through a recent collision with another galaxy, but astronomers can’t find the culprit anywhere near.
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What Venus and Saturn Have in Common
Astronomers have known about a strange vortex at the south pole of Venus since the 1970s, when it was discovered by NASA’s Pioneer Venus spacecraft. And recently, the Cassini spacecraft imaged a similar vortex at Saturn’s southern pole. The two vortices are caused when an area of low pressure sits at the rotation pole of a planet. This causes air to spiral down from higher in the atmosphere, like water going down a drain. Any planet with an atmosphere, even the Earth, can form a vortex like this. Venus’ vortex is unusual because it has two eyes that rotate around each other.
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Double Supernovae in a Distant Galaxy
NASA’s Swift satellite has found a galaxy positively popping with supernovae. NGC 1316 has had two supernovae go off in just the last 5 months, and 4 within the 26 years. This makes NGC 1316 one of the most supernova rich galaxies ever discovered. So, what’s going on here? Astronomers know that the galaxy recently merged with a spiral galaxy, which can produce massive stars that explode as supernovae. However, all four supernovae have been Type 1a, which are formed when a white dwarf consumes material from a binary partner star. Perhaps it’s just a coincidence.
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Back to Venus with Vesper
While Venus is the same size as our Earth, its hellish surface environment makes it inhospitable to life. What went wrong with Venus? Now NASA is working on a new spacecraft called Vesper that could visit Venus, and try to get to the bottom of the question. Once launched, Vesper could begin orbiting Venus in March 2015. It would have a suite of instruments that would analyze the planet’s atmosphere over the course of two years.
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NASA Losing Hope for Mars Global Surveyor
NASA is starting to lose hope that they’ll be able to communicate with the Mars Global Surveyor, which hasn’t called home since November 2. Mission controllers tried to communicate with the spacecraft again on Tuesday, and didn’t hear anything. The spacecraft originally launched on November 7, 1996, and has returned more than 240,000 images of the Red Planet. It’s likely that the spacecraft’s solar panels are unable to pivot to face the Sun, so it doesn’t have enough power to communicate.
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Podcast: A Universe of Dark Energy
The discovery of dark energy was one of the biggest surprises in astronomy. Instead of a nice, predictable expanding Universe, acted on only by gravity, astronomers turned up a mysterious repulsive force accelerating the expansion of the Universe. Fraser and Pamela explain the evidence for a dark energy, and a few possible theories for what could be providing this repulsive force.
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Dark Matter Halo Around the Milky Way
NASA’s most powerful supercomputer has helped researchers simulate the halo of dark matter that surrounds the Milky Way. This dark matter is invisible to our telescopes; however, it does interact with regular matter through its gravity. This new computer simulation shows how the dark matter clumps together into “subhalos” within the larger halo surrounding the Milky Way. This is a bit of a puzzle, since the dark matter doesn’t match the clumping of the satellite galaxies that surround us.
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