Discovered by K. Reinmuth MPC designation 1150 Achaia Alternative names 1929 RB · 1955 SZ1 Discovered 2 September 1929 Discoverer Karl Wilhelm Reinmuth | Discovery date 2 September 1929 Pronunciation /əˈkaɪə/ Minor planet category main-belt · Flora Orbits Sun | |
Discovery site Landessternwarte Heidelberg-Königstuhl Similar 1111 Reinmuthia, 1056 Azalea, 847 Agnia, 276 Adelheid, 911 Agamemnon | ||
1150 Achaia (/əˈkaɪə/), provisional designation 1929 RB, is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 7.8 kilometers in diameter. It was discovered on 2 September 1929, by German astronomer Karl Reinmuth at Heidelberg Observatory in southwest Germany. Ten nights later, it was independently discovered by Friedrich Schwassmann and Arno Wachmann at Bergedorf. It is named for the Greek region of Achaia.
Description
The stony S-type asteroid is a member of the Flora family, one of the largest families of the main-belt. It orbits the Sun at a distance of 1.7–2.6 AU once every 3 years and 3 months (1,184 days). Its orbit has an eccentricity of 0.20 and an inclination of 2° with respect to the ecliptic. Achaia's observation arc begins at Heidelberg, five days after its official discovery observation. No precoveries were taken and no prior identifications were made.
A rotational lightcurve of Achaia was obtained by Czech astronomer Petr Pravec at Ondřejov Observatory in October 2007. It gave a well-defined rotation period of 60.99 hours with a brightness variation of 0.72 magnitude (U=3). Publsihed in 2016, two additional lightcurves were derived from modeled photometric data using various sources. They gave a sideral rotation period of 61.071 and 61.072 hours, as well as a spin axis of (5.0°, −65.0°) and (20.0°, −69.0°) in ecliptic coordinates, respectively. While not being a slow rotator, Achaia has s notably longer period than the vast majority of asteroids, which typically rotate every 2 to 20 hours once around their axis. Also, the body's changes in brightness are relatively high and indicate that it has a non-spheroidal shape.
According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Achaia measures between 7.689 and 8.16 kilometers in diameter, and its surface has an albedo between 0.234 and 0.251. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – taken from 8 Flora, the family's principal body and namesake – and calculates a diameter of 7.82 kilometers based on an absolute magnitude of 12.7.
This minor planet is named for the region Achaea (or "Achaia") in Western Greece. It is located in the northern part of the Peloponnese peninsula and borders on the gulfs of Patras and Corinth. Naming citation was first mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 107).