9084 Achristou

9084 Achristou (provisional designation ) is a stony Hungaria asteroid from the innermost regions of the asteroid belt, about 1.9 kilometers in diameter. It was discovered by British astronomer David J. Asher at Siding Spring Observatory in New South Wales, Australia, on 3 February 1995. The asteroid was named after British planetary astronomer Apostolos Christou.

Orbit and classification
Achristou is a member of the Hungaria family, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun at a distance of 1.7–2.0 AU once every 2 years and 6 months (926 days). Its orbit has an eccentricity of 0.08 and an inclination of 23° with respect to the ecliptic. In April 1980, it was first identified as at Palomar Observatory, extending the body's observation arc by 15 years prior to its official discovery observation at Siding Spring.

Physical characteristics
Achristou has been characterized as a bright E-type asteroid.

Rotation period
In May 2013, a rotational lightcurve of Achristou was obtained from photometric observations by American astronomer Robert Stephens at the Center for Solar System Studies (U81) in California. Lightcurve analysis gave a rotation period of $1.916$ hours with a low brightness variation of 0.09 magnitude (U=2+).

Diameter and albedo
Based on the survey carried out by the NEOWISE mission of NASA's space-based Wide-field Infrared Survey Explorer, Achristou measures 1.9 kilometers in diameter and its surface has an albedo of 0.33, while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 and calculates a diameter of 1.8 kilometers with an absolute magnitude of 15.7.

Naming
This minor planet was named after Apostolos Christou (born 1968), planetary astronomer and programmer at the North Irish Armagh Observatory, after which the minor planet 10502 Armaghobs was named. His field or research include minor planets in co-orbit with Venus, designing near-Earth asteroids missions, the dwarf planet 1 Ceres, meteor impacts on Venus, as well as the irregular satellite families of the outer planets. The official naming citation was published by the Minor Planet Center on 23 May 2005 (M.P.C. 54173).