Tag Archives: asteroid

Super. Massive. Impressive.

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This image from NASA’s Chandra X-ray Observatory shows the center of our Galaxy, with a supermassive black hole known as Sagittarius A* (Sgr A* for short) in the center. Using intermittent observations over several years, Chandra has detected X-ray flares about once a day from Sgr A*. The flares have also been seen in infrared data from ESO’s Very Large Telescope in Chile.

A new study provides a possible explanation for the mysterious flares. The suggestion is that there is a cloud around Sgr A* containing hundreds of trillions of asteroids and comets , which have been stripped from their parent stars. The panel on the left is an image containing nearly a million seconds of Chandra observing of the region around the black hole, with red representing low-energy X-rays, green as medium-energy X-rays, and blue being the highest.

An asteroid that undergoes a close encounter with another object, such as a star or planet, can be thrown into an orbit headed towards Sgr A*, as seen in a series of artist’s illustrations beginning with the top-right panel. If the asteroid passes within about 100 million miles of the black hole, roughly the distance between the Earth and the Sun, it would be torn into pieces by the tidal forces from the black hole (middle-right panel).

These fragments would then be vaporized by friction as they pass through the hot, thin gas flowing onto Sgr A*, similar to a meteor heating up and glowing as it falls through Earth’s atmosphere. A flare is produced (bottom-right panel) and eventually the remains of the asteroid are swallowed by the black hole.  … (Chandra)

Ice fiesta on Vesta?

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Though generally thought to be quite dry, roughly half of the giant asteroid Vesta is expected to be so cold and to receive so little sunlight that water ice could have survived there for billions of years, according to the first published models of Vesta’s average global temperatures and illumination by the sun.

“Near the north and south poles, the conditions appear to be favorable for water ice to exist beneath the surface,” says Timothy Stubbs of NASA’s Goddard Space Flight Center in Greenbelt, Md., and the University of Maryland, Baltimore County. Stubbs and Yongli Wang of the Goddard Planetary Heliophysics Institute at the University of Maryland published the models in the January 2012 issue of the journal Icarus. The models are based on information from telescopes including NASA’s Hubble Space Telescope. …(NASA)

2005 YU55 in ultraviolet

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Asteroid 2005 YU55 whisks through the field of view of Swift’s Ultraviolet/Optical Telescope (UVOT) on Nov. 9, just hours after the space rock made its closest approach to Earth. The video plays on a background image from the Digital Sky Survey that shows the same region, which lies within the Great Square asterism of the constellation Pegasus (times UT). (Credit: NASA/Swift/Stefan Immler and DSS)

 

It all started with a bang

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Scientists have found a recipe for cooking the solar system from scratch: take a cold cloud of gas, and set it 15 light-years from an exploding supernova. Stun the cloud with the supernova’s shockwave. Incubate, and watch as the solar system begins to take shape.

New computer simulations support this scenario, which is a plausible recounting of the solar system’s birth, reports a team of scientists in an upcoming issue of the Astrophysical Journal. “With the supernova, you have one triggering event, and you don’t have to invoke a complicated chain of events,” says study author Matthias Gritschneder, an astrophysicist at the University of California, Santa Cruz.

Understanding how the local solar neighborhood grew up is crucial for learning how other planetary systems are born.

Scientists think the sun and surrounding planets were born from a churning disk of gas and dust, but what precisely caused the stuff to condense and form these bodies has been a mystery. Some clues appear in radioactive elements that were injected into and swam around the presolar cloud. Today, they are embedded in objects such as asteroids, and are thought to mark the first solid bodies that emerged after the cloud’s collapse. … (ScienceNews)

A close shave – but not too close

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On November 8–9, 2011, the Earth-crossing asteroid 2005 YU55 will speed past us at a distance closer than the Moon. With a diameter of about 400 meters, it will be the largest object that’s ever been seen passing so close. It should reach about magnitude 11.2 at its brightest, as told in the November Sky & Telescope, page 53.

Several professional groups plan to study the asteroid during the crucial days and hours of closest approach. They are seeking help from amateurs who are set up to do accurate photometry. … (S&T)