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YORP effect: As scientists watch, distant asteroid disintegrates


Jamie D:
The Yarkovsky–O'Keefe–Radzievskii–Paddack effect, or YORP effect for short, is a second-order variation on the Yarkovsky effect which changes the rotation rate of a small body (such as an asteroid). The term was coined by David P. Rubincam in 2000.

In the 19th century, Yarkovsky realised that the infrared radiation escaping from a body warmed by the Sun carries off momentum as well as heat. Translated into modern physics, each photon escaping carries away a momentum p = E/c where E (= hν) is its energy and c is the speed of light. Radzievskii applied the idea to rotation based on changes in albedo[1] and Paddack and O'Keefe realised that shape was a much more effective means of altering a body's spin rate. Paddack and Rhee suggested that the YORP effect may be the cause of rotational bursting and eventual elimination from the solar system of small asymmetric objects.

Wikipedia entry

As scientists watch, distant asteroid disintegrates

Reuters | William Dunham

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....

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....

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.

Full article at the link

  First instance imaged of an asteroid breakup.  I have done asteroid confirmations at my club's site and do have an IAU observatory code for that site because of it.  There are lots of images of comets breaking up due to the volatility of those objects.  Comet Shoemaker-Levy 9 is one example of that when it broke up when captured by Jupiter's gravity and then the pieces slammed into the Jovian upper atmosphere providing a view of multiple "black eyes" visible for weeks with the small backyard telescopes.  However, most of the asteroids are "rubble piles" of various sizes of rocks and dust.  It is theorized that these rubble piles do break up and then re-coalesce due to the lack of ice found in them.  Some asteroids do breakup due to the YORP effect or by getting too close to a large body such as the Earth or other planets. 
  Most of the early flybys of asteroids were of the cratered dust covered large rocks with some having a tiny moon around them.  P/2013 R3, the asteroid pictured breaking up is an example of a rubble pile is designated as a comet.  The designation given is a date coded type.  The P before the slash stands for "periodical" usually reserved for comets.  Since this asteroid is now acting like a comet, it gets a P.  2013, the year of discovery; R meaning Sept 1-15; 3, the order within that half-month of the discovery. 
  25143 Itokawa, is an example of a rubble pile asteroid.  The number is the final designation of an asteroid or dwarf planet after much research has been done of that particular body and the name is the accepted name by the naming committee of the IAU.  It was named after a Japanese rocket scientist.  It was visited by the Japanese probe Hayabusa and the probe returned the first and only soil sample return of an asteroid to Earth.  Below is the image of Itokawa taken by the Hayabusa space probe, showing a textbook image of a rubble pile.  The rotation is along the length causing the peanut or dog bone shape of these objects.



Jill F:
My theory

Ms Grace:
My theory…


Jamie D:
Oh my gosh, Jill.  I have not thought of the Asteroids game in 30 years.  Damn, I dropped hundreds of quarters into those machines.


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