354P/LINEAR

Further information: List of comets discovered by the LINEAR project

354P/LINEAR, provisionally designated P/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]

354P/LINEAR

Hubble Space Telescope image of 354P/LINEAR with dusty impact debris on 2 February 2010
Discovery[1]
Discovered by	LINEAR (704)
Discovery date	6 January 2010
Designations
Minor planet category	Asteroid[2] Small Solar System body
Orbital characteristics[3]
Epoch 13 October 2010 (JD 2455482.5)
Aphelion	2.58 AU (Q)
Perihelion	2.01 AU (q)
Semi-major axis	2.29 AU (a)
Eccentricity	0.1246
Orbital period (sidereal)	3.47 yr
Mean anomaly	88.9° (M)
Inclination	5.25°
Longitude of ascending node	320°
Time of perihelion	2023-Oct-13[4]
Argument of perihelion	133°
Physical characteristics
Dimensions	172.4 × 88.8 m[5]
Mean diameter	123.8+33.6 −18.4 m[5]
Synodic rotation period	11.36±0.02 h
Albedo	unknown
Apparent magnitude	~18-20[1]
Absolute magnitude (H)	21.3±0.6[6]

Discovery

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 (39 in) 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.

Orbit

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 frost line 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]'

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] One asteroid of the Flora family, 2010 AA₁₅, was initially suspected to have collided with P/2010 A2 due to their very similar orbits, but was later deemed a coincidence.^[15][16]

Cause of activity

354P/LINEAR as seen an 8 min photo with a 24" telescope

Observations with the Hubble Space Telescope^[17] and the narrow angle camera on board the Rosetta spacecraft^[18] 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.^[19]

P/2010 A2 is likely about 150 meters (490 feet) in diameter.^[12] Even when it was discovered it was suspected of being less than 500 meters in diameter.^[20]

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

See also

• 493 Griseldis
• 596 Scheila
• P/2016 G1 (PanSTARRS)