(Redirected from P/2010 A2)

354P/LINEAR (formerly 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.[7] 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 the dust halo, a situation never before seen in a comet.[7] The tail is created by millimeter-sized particles being pushed back by solar radiation pressure.[9][10]

Main-belt object 354P/LINEAR (P/2010 A2) as seen in an 8 min photo with a 24" telescope
Discovered byLINEAR (704)
Discovery date2010-01-06
Orbital characteristics[2]
Epoch 13 October 2010 (JD 2455482.5)
Aphelion2.58 AU (Q)
Perihelion2.01 AU (q)
2.29 AU (a)
3.47 yr
88.9° (M)
Physical characteristics
  • 220±40 m[6]
  • ~140 m (460 ft)[7]


Orbit of P/2010 A2 at the time of its discovery

P/2010 A2 was discovered on 6 January 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.[11][12] 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.[13] Beyond the frostline volatile ices are generally more common. Early observations did not detect water vapor or other gases.[7] 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.[6]

Observations with the Hubble Space Telescope[14] and the narrow angle camera on board the Rosetta spacecraft[15] 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.[16]

P/2010 A2 is likely about 150 meters (460 feet) in diameter.[7] Even when it was discovered it was suspected of being less than 500 meters in diameter.[17]

Another object, centaur 60558 Echeclus in 2006, was suspected of outgassing as a result of an undetermined splitting event.[18]

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.[7] The Flora family of asteroids may be the source of the Chicxulub (Cretaceous–Paleogene) impactor, the likely culprit in the extinction of the dinosaurs.[7]

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

See alsoEdit

Possible asteroid collision eventsEdit


  1. ^ a b c d Marsden, Brian G. (7 January 2010). "MPEC 2010-A32 : COMET P/2010 A2 (LINEAR)". IAU Minor Planet Center. Harvard-Smithsonian Center for Astrophysics. Retrieved 14 January 2010.
  2. ^ a b c d e f "JPL Small-Body Database Browser: P/2010 A2 (LINEAR)" (last observation: 2012-10-14; arc: 2.83 years). Retrieved 3 February 2010.
  3. ^ "When is a comet not a comet? Rosetta finds out". ESA News. 13 October 2010. Retrieved 15 October 2010.
  4. ^ a b c Jewitt, David C. "P/2010 A2 (LINEAR): The 5th Main-Belt Comet". UCLA (Department of Earth and Space Sciences). Retrieved 20 January 2010.
  5. ^ JPL Horizons Observer Location: @sun (Perihelion occurs when deldot changes from negative to positive.)
  6. ^ a b Méndez, Javier (23 July 2010). "Comet P/2010 A2, an Activated Asteroid from the Main Asteroid Belt". Isaac Newton Group of Telescopes (ING). Retrieved 27 July 2010.
  7. ^ a b c d e f g Harrington, J. D.; Villard, Ray (2 February 2010). "Suspected Asteroid Collision Leaves Trailing Debris". NASA Release : 10-029. Retrieved 3 February 2010.
  8. ^ 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.
  9. ^ HST Sees Evidence of Colliding Asteroids, Astronomy Today, Feb.2, 2010
  10. ^ Jewitt, David C. "P/2010 A2 (LINEAR): Possible Asteroid Smash". UCLA (Department of Earth and Space Sciences). Retrieved 3 February 2010.
  11. ^ Hergenrother, Carl W.; The Curious Case of Comet LINEAR, The Transient Sky, 10 January 2010 (1.8-m telescope on Kitt Peak)
  12. ^ Catalogue of Comet Discoveries, Comethunter.de
  13. ^ "Glossary of Astronomical Terms (Ice line)". Glossary of Astronomical Terms. Archived from the original on 14 February 2010. Retrieved 20 January 2010.
  14. ^ Jewitt, David C.; Weaver, Harold; Agarwal, Jessica; Mutchler, Max; et al. (2010). "A recent disruption of the main-belt asteroid P/2010?A2". Nature. 467 (7317): 817–9. Bibcode:2010Natur.467..817J. doi:10.1038/nature09456. PMID 20944743.
  15. ^ Snodgrass, Colin; Tubiana, Cecilia; Vincent, Jean-Baptiste; Sierks, Holger; Hviid, Stubbe; Moissl, Richard; Boehnhardt, Hermann; Barbieri, Cesare; et al. (2010). "A collision in 2009 as the origin of the debris trail of asteroid P/2010?A2". Nature. 467 (7317): 814–6. arXiv:1010.2883. Bibcode:2010Natur.467..814S. doi:10.1038/nature09453. PMID 20944742.
  16. ^ Harrington, J. D.; Weaver, Donna; Jewitt, David C. (13 October 2010). "Hubble Finds that a Bizarre X-Shaped Intruder Is Linked to an Unseen Asteroid Collision". Hubblesite newscenter STScI-2010-34. Retrieved 15 October 2010.
  17. ^ Shanklin, Jonathan (18 January 2010). "BAA Comet Section : Comets discovered in 2010". Institute of Astronomy (British Astronomical Association). Retrieved 21 January 2010.
  18. ^ Hecht, Jeff (11 April 2006). "Hybrid comet-asteroid in mysterious break-up". NewScientist.com news service. Retrieved 18 April 2006.

External linksEdit