354P/LINEAR, provisionally designatedP/2010 A2 (LINEAR), is a small main-belt asteroid that was impacted by another asteroid sometime before 2010. It was discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) at Socorro, New Mexico on 6 January 2010. The asteroid possesses a dusty, X-shaped, comet-like debris trail that has remained nearly a decade since impact.[5] 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 tail is created by millimeter-sized particles being pushed back by solar radiation pressure.[7][8]
Overview
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.[9][10] It has been observed over a 112-day arc of the 3.5 year orbit.[3] It appears to have come to perihelion (closest approach to the Sun) around the start of December 2009,[3] about a month before it was discovered.
With an aphelion (furthest distance from the Sun) of only 2.6 AU,[3] P/2010 A2 spends all of its time inside of the frostline at 2.7 AU.[11] Beyond the frostline volatile ices are generally more common. Early observations did not detect water vapor or other gases.[12] 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.[13] 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.[14]
354P/LINEAR as seen an 8 min photo with a 24" telescope
Observations with the Hubble Space Telescope[15] and the narrow angle camera on board the Rosetta spacecraft[16] 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.[17]
P/2010 A2 is likely about 150 meters (460 feet) in diameter.[12] Even when it was discovered it was suspected of being less than 500 meters in diameter.[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.[12] The Flora family of asteroids may be the source of the Chicxulub (Cretaceous–Paleogene) impactor, the likely culprit in the extinction of the dinosaurs.[12]
Debris field
P/2010 A2 is likely the debris left over from a recent collision between two very small asteroids.
Surviving fragment
Surviving fragment seen to the lower left of debris field
^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.
^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. PMID20944742. S2CID4330570.
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