Astronomers spot rare asteroid break-up

[Buster's Uncle]

Astronomers spot rare asteroid break-up
AFP
58 minutes ago



A handout photo released on March 6, 2014 by the ESA shows the NASA/ESA Hubble Space Telescope observations of asteroid P/2013 R3 (AFP Photo/D. Jewitt)


     
Washington (AFP) - Astronomers said Thursday they have witnessed the distant break-up of an asteroid, a rare event that was not caused by a violent space collision or a close encounter with the Sun.

Instead, the asteroid, located some 300 million miles (483 million kilometers) from the Sun, was likely weakened over time by multiple small run-ins with other space objects, said the report in Astrophysical Journal Letters.

And now, astronomers are watching asteroid P/2013 R3 come undone as a result of a subtle effect of sunlight, which causes the asteroid to rotate at an increasingly fast rate.

"Seeing this rock fall apart before our eyes is pretty amazing," said lead investigator David Jewitt, a professor in the University of California Los Angeles Department of Earth, Planetary and Space Sciences.

Jewitt said the asteroid has broken into as many as 10 pieces and is gently being pulled apart by centrifugal force, "like grapes on a stem."

The photographs of the break-up were captured by the Hubble Space Telescope.

Each of the 10 parts have comet-like dust tails, and the biggest four chunks are each double the size of a football field.

The asteroid's unraveling began last year.

The latest Hubble pictures show the fragments "drifting away from each other at a leisurely pace of one mile per hour — slower than a strolling human," said a UCLA press statement.

Eventually, the fragments, which are estimated to weigh 200,000 tons, will provide a rich source of meteoroids.

Most of them will plunge into the Sun although some may be witnessed as meteors across the Earth's sky, Jewitt said.

The Hubble Space Telescope is a collaborative project between NASA and the European Space Agency.


http://news.yahoo.com/astronomers-spot-rare-asteroid-break-162252242.html

[Buster's Uncle]

As scientists watch, distant asteroid disintegrates
Reuters
By Will Dunham  2 hours ago



This series of Hubble Space Telescope images reveals the breakup of an asteroid over a period of several months in late 2013. Scientists said on Thursday they have observed for the first time an asteroid breaking apart, crumbling into at least 10 pieces in sort of a celestial, slow-motion train wreck. The images were taken in visible light with Hubble's Wide-Field Camera 3. REUTERS/NASA, ESA, D. Jewitt/UCLA/Handout via Reuters



WASHINGTON (Reuters) - Patsy Cline's classic country song "I Fall to Pieces," has nothing on this one.

Scientists said on Thursday they have observed for the first time an asteroid breaking apart, crumbling into at least 10 pieces in sort of a celestial, slow-motion train wreck.

The rocky asteroid, named P/2013 R3, was one of the innumerable objects populating the crowded asteroid belt located between the orbits of Mars and Jupiter, roughly three times further away from the sun than Earth.

Asteroids have broken apart many times over the eons, but never before have scientists been able to witness it.

This time, however, scientists first noticed the dramatic events using ground-based telescopes in Arizona and Hawaii and then got a better look using the orbiting Hubble Space Telescope.

"After looking at the asteroid belt for a couple of hundred years - the first one was discovered in 1801 - to find a new thing like this is really exciting," David Jewitt, a UCLA astronomer who led the research, said in a telephone interview.

The findings were published in the scientific publication Astrophysical Journal Letters.

The asteroid was probably around 2,000 feet in diameter, and no more than about 3,280 feet in diameter before it began to disintegrate, Jewitt said. The break-up unfolded over a period of several months last year, he added.

The Hubble telescope detected at least 10 fragments - each having comet-like dust tails. The four largest pieces each had a diameter of up to about 1,300 feet.

The scientists do not think the asteroid was destroyed in a collision with another object in part because the way it is breaking apart - fragments drifting slowly at around one mile per hour - does not suggest a violent impact.

In addition, the 10 fragments did not all emerge at one time, as they would in an impact, with their appearance staggered over many months, Jewitt said.

They also think it is unlikely the asteroid fell to pieces due to the pressure of interior ices warming and vaporizing because at 300 million miles (480 million km) away from the sun it simply would be too cold for that to occur.

Instead, they said the break-up was probably the result of the subtle but inexorable effect of sunlight over many, many years causing the asteroid to spin at a slowly increasing rate until it became unstable and ruptured. This phenomenon, known as the YORP effect, has been debated by scientists, but never previously reliably observed.

"This is a really bizarre thing to observe - we've never seen anything like it before," added Jessica Agarwal of the Max Planck Institute for Solar System Research in Germany. "The break-up could have many different causes, but the Hubble observations are detailed enough that we can actually pinpoint the process responsible."

When hit with sunlight, objects radiate heat back into space. If an object is perfectly round, that phenomenon would not affect its structural stability. But the irregular shape of asteroids - often shaped like a big potato tumbling through space - means that when sunlight is radiated back into space, it exerts a torque on them, leading to a spin.

"That net force due to sunlight is very, very weak. But on long time scales, it can push asteroids around," Jewitt said. "So this is probably the way asteroids die in many cases. They spin up and blow themselves apart. And in the process, they make dust and debris that populates the inner solar system."


http://news.yahoo.com/scientists-watch-distant-asteroid-disintegrates-170944981.html

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