354P/LINEAR

Orbit

With an aphelion (furthest distance from the Sun) of only 2.6 AU, P/2010 A2 spends all of its time inside of the frost line at 2.7 AU. Beyond the frostline volatile ices are generally more common. Early observations did not detect water vapor or other gases. 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. 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.

354P was originally thought to belong to the Flora family, an asteroid family produced by a disruptive collision more than 100 million years ago. The Flora family of asteroids may be the source of the Chicxulub impactor, a possible culprit in the extinction of the non-avian dinosaurs. However, subsequent studies on 354P's dynamics have instead shown an association with the Baptistina family, estimated to be around 100–320 million years old, and a refuted candidate for the Chicxulub Impactor after being ruled out by a Wide-field Infrared Survey Explorer (WISE) study. 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.

Cause of activity

Observations with the Hubble Space Telescope and the narrow angle camera on board the Rosetta spacecraft 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.

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