1181 Lilith (prov. designation: ) is a metallic asteroid from the middle region of the asteroid belt, approximately 23 km in diameter. It was discovered on 11 February 1927, by Russian–French astronomer Benjamin Jekhowsky at Algiers Observatory in Algeria, Northern Africa, and named after French composer Lili Boulanger.

Classification and orbit

Lilith is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the middle asteroid belt at a distance of 2.1–3.2 AU once every 4 years and 4 months (1,587 days). Its orbit has an eccentricity of 0.20 and an inclination of 6° with respect to the ecliptic. First observed as at Simeiz Observatory in 1914, Lilith's observation arc begins 7 years after its official discovery observation, with its first used observation made at Konkoly Observatory in 1934.

Naming

This minor planet was named by the discoverer for French composer Marie-Juliette Olga Lili Boulanger (1893–1918), younger sister of the noted conductor and composer, Nadia Boulanger. Her byname "Lili" originates from Lilith, Adam's first wife in Jewish mythology (H 110).

Physical characteristics

Lilith is an X-type asteroid in the Bus–Binzel SMASS taxonomy. It has also been classified as a P-type asteroid by NASA's space-based Wide-field Infrared Survey Explorer (WISE).

Rotation period

In February 2014, a rotational lightcurve of Lilith was obtained by Italian astronomer Andrea Ferrero at the Bigmuskie Observatory in Mombercelli, Italy. The photometric observations rendered a period of 15.04 hours with a brightness amplitude of 0.11 in magnitude (U=2).

Diameter and albedo

According to NASA's WISE telescope with its subsequent NEOWISE mission, Lilith measures (20.492) kilometers in diameter and its surface has an albedo of (0.106), while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.10, and calculates a diameter of 24.2 kilometers with an absolute magnitude of 11.2. The WISE team also published an alternative mean diameter (22.133 km) and an albedo of (0.116).