G. van Biesbroeck
11 November 1923
George Van Biesbroeck
11 November 1923
Minor planet category
main-belt · Themis
Aesculapius (Greek/Roman deity)
A923 YO11 · 1942 DH 1977 LP1 · A899 PE A908 AE
Sun, 1002 Olbersia, 1056 Azalea, 1001 Gaussia, 132 Aethra
1027 Aesculapia, provisional designation A923 YO11, is a Themistian asteroid from the outer region of the asteroid belt, approximately 33 kilometers in diameter. It was discovered on 11 November 1923, by Belgian–American astronomer George Van Biesbroeck at Yerkes Observatory in Williams Bay, Wisconsin, United States. It is named for Aesculapius, the god of medicine in Greek mythology.
Aesculapia is a member of the Themis family, a dynamical group of carbonaceous outer-belt asteroids which are known for their nearly coplanar ecliptical orbits. It orbits the Sun at a distance of 2.7–3.6 AU once every 5 years and 7 months (2,044 days). Its orbit has an eccentricity of 0.13 and an inclination of 1° with respect to the ecliptic. In 1889, it was first identified as A899 PE at Harvard Observatory's Boyden Station in Arequipa, Peru. The body's observation arc begins at Heidelberg in 1908, when it was identified as A908 AE, 15 years prior to its official discovery observation at Williams Bay.
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, Aesculapia measures between 31.225 and 38.55 kilometers in diameter, and its surface has an albedo between and 0.06 and 0.129. The Collaborative Asteroid Lightcurve Link (CALL) derives an albedo of 0.075 and a diameter of 32.05 kilometers with an absolute magnitude of 10.9. Despite the body's low albedo, CALL classifies Aesculapia as a S-type rather than a C-type asteroid.
In the last 20 years, photometric observations of Aesculapia gave several rotational lightcurves with significantly divergent rotation periods. First results obtained by Chester Maleszewski and René Roy were only fragmentary or incorrect (U=1/1). Photometry at the Palomar Transient Factory and observations by Astronomer Steven Ehlert gave a period of 9.791 and 19.506 hours with a brightness amplitude of 0.09 and 0.19 magnitude, respectively (U=2/2). CALL currently adopts a lightcurve obtained by Kylie Hess at Oakley Southern Sky Observatory in March 2015, which gave a period of 13.529 hours and a brightness variation of 0.09 magnitude (U=2).
This minor planet was named for Aesculapius, the Greek and Roman demigod of medicine and healing, son of Apollo and Coronis, after whom the asteroids 158 Koronis and 1862 Apollo are named, respectively. Naming citation was first mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 98).