P/2010 A2

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P/2010 A2 (LINEAR)
240px
Main-belt comet P/2010 A2 as seen in an 8 min photo with a 24" telescope
Discovery[1]
Discovered by LINEAR (704)
Discovery date 2010-01-06
Designations
Comet[2]
Asteroid[3]
Main-belt comet[4]
Small Solar System body
Orbital characteristics[2]
Epoch 2010-Oct-13
Aphelion 2.58 AU (Q)
Perihelion 2.01 AU (q)
2.29 AU (a)
Eccentricity 0.1246
3.47 yr
88.9° (M)
Inclination 5.25°
320°
133°
Physical characteristics
Dimensions 220±40 m[5]
~140 m (460 ft)[6]
Albedo unknown
~18-20[1]
21.3±0.6[7]

P/2010 A2 (LINEAR) is a small Solar System body that displayed characteristics of both an asteroid and a comet, and thus, was initially given a cometary designation.[1] Because it has the orbit of a main-belt asteroid and showed the tail of a comet, it was listed as a main-belt comet.[2][4] But within a month of discovery, an analysis of images by the Hubble telescope suggested that its tail was generated by dust and gravel resulting from a recent head-on collision between asteroids rather than from sublimation of cometary ice.[6] This was the first time a small-body collision had been observed; since then, minor planet 596 Scheila has also been seen to undergo a collision, in late 2010. The position of the nucleus was remarkable for being offset from the axis of the tail and outside of the dust halo, a situation never before seen in a comet.[6] The tail is created by millimeter-sized particles being pushed back by solar radiation pressure.[8][9]

Overview

File:P 2010 A2 Orbit.gif
Orbit of P/2010 A2 at the time of its discovery

P/2010 A2 was discovered on January 6, 2010 by Lincoln Near-Earth Asteroid Research (LINEAR) using a 1-meter (36") reflecting telescope with a CCD camera.[1] It was LINEAR's 193rd comet discovery.[10][11] It has been observed over a 112-day arc of the 3.5 year orbit.[2] It appears to have come to perihelion (closest approach to the Sun) around the start of December 2009,[2] about a month before it was discovered.

With an aphelion (furthest distance from the Sun) of only 2.6 AU,[2] P/2010 A2 spends all of its time inside of the frostline at 2.7 AU.[12] Beyond the frostline volatile ices are generally more common. Early observations did not detect water vapor or other gases.[6] Within less than a month of its discovery it was doubtful that the tail of P/2010 A2 was generated via active outgassing from sublimation of ices hidden beneath the crust.[4] Early modeling indicated that the asteroid became active in late March 2009, reached maximum activity in early June 2009, and eased activity in early December 2009.[5]

Observations with the Hubble space telescope[13] and the narrow angle camera on board the Rosetta spacecraft[14] indicate that the dust trail seen was probably created by the impact of a small meter size object on the larger asteroid in February or March 2009, although it cannot be ruled out that the asteroid's rotation increased from solar radiation resulting in a loss of mass that formed a comet-like tail.[15]

P/2010 A2 is likely about 150 meters (460 feet) in diameter.[6] Even when it was discovered it was suspected of being less than 500 meters in diameter.[16]

Another object, centaur 60558 Echeclus in 2006, was suspected of outgassing as a result of an undetermined splitting event.[17]

The orbit of P/2010 A2 is consistent with membership in the Flora asteroid family, produced by collisional shattering more than 100 million years ago.[6] The Flora family of asteroids may be the source of the Chicxulub (Cretaceous–Paleogene) impactor, the likely culprit in the extinction of the dinosaurs.[6]

Debris field?
350px
P/2010 A2 is likely the debris left over from a recent collision between two very small asteroids.
Comet nucleus
Asteroid P-2010 A2.jpg
Assumed comet nucleus seen to the lower left of debris field

See also

Possible asteroid collision events

References

  1. ↑ 1.0 1.1 1.2 1.3 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ This absolute asteroidal V magnitude has been calculated using comet/asteroid magnitude analysis software "Comet for Windows" from value of R = 23.0 ± 0.5 taken from IAU Circular No. 9109. The mean V-R color index for asteroids is +0.4 ± 0.1.
  8. ↑ HST Sees Evidence of Colliding Asteroids, Astronomy Today, Feb.2, 2010
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Hergenrother, Carl W.; The Curious Case of Comet LINEAR, The Transient Sky, January 10, 2010 (1.8-m telescope on Kitt Peak)
  11. ↑ Catalogue of Comet Discoveries, Comethunter.de
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

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