Discovered by H. Alikoski Absolute magnitude 9.62 Discoverer Heikki A. Alikoski | Discovery date 18 March 1939 Discovered 18 March 1939 Orbits Sun Discovery site Iso-Heikkilä Observatory | |
Alternative names 1939 FE · 1938 CU1957 TA · 1958 XS People also search for Sun, 2487 Juhani, 1697 Koskenniemi | ||
1512 Oulu, provisional designation 1939 FE, is a rare-type Hildian asteroid and slow rotator from the outermost region of the asteroid belt. With a diameter of about 80 kilometers, it belongs to the fifty largest asteroids in the outer main-belt. The body was discovered on 18 March 1939, by Finnish astronomer Heikki Alikoski at Turku Observatory in Southwest Finland and named for the Finnish town Oulu.
Description
Located in the outermost part of the main-belt, Oulu is a member of the Hilda family, a large orbital group of asteroids that are thought to have originated from the Kuiper belt. They orbit in a 3:2 orbital resonance with the gas giant Jupiter, meaning that for every 2 orbits Jupiter completes around the Sun, a Hildian asteroid will complete 3 orbits. As it does not cross the path of any of the planets, it will not be pulled out of orbit by Jupiter's gravitational field, and will likely remain in a stable orbit for thousands of years.
Oulu is classified as a dark and reddish P-type asteroid in the Tholen taxonomy, of which only a few dozens bodies are currently known. It orbits the Sun at a distance of 3.4–4.6 AU once every 7 years and 11 months (2,890 days). Its orbit has an eccentricity of 0.15 and an inclination of 6° with respect to the ecliptic. In 1938, Oulu was first identified as 1938 CU at Bergedorf Observatory. Its observation arc, however, begins one month after its official discovery observation.
In May 2009, a rotational light-curve was obtained from photometric observations by Slovak astronomer Adrián Galád at Modra Observatory. Light-curve analysis gave a rotation period of 132.3 hours with a brightness variation of 0.33 in magnitude (U=2+). It is among the top few hundred slow rotators.
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Oulu measures between 65.00 and 91.05 kilometers in diameter, and its surface has an albedo between 0.031 and 0.06. The Collaborative Asteroid Lightcurve Link agrees with IRAS, that is, an albedo of 0.0366 and a diameter of 82.72 kilometers using an absolute magnitude of 9.62. In May 2002, Vasilij Shevchenko and Edward Tedesco observed an occultation by Oulu, that gave a diameter of 65.0 kilometers with an occultation albedo of 0.0594.
This minor planet was named for the northern Finnish town Oulu, the birthplace of the discoverer. Naming citation was published before November 1977 (M.P.C. 2278).