Discovered by G. Neujmin MPC designation 789 Lena Minor planet category main-belt · (middle) Orbits Sun Asteroid group Asteroid belt | Discovery date 24 June 1914 Alternative names 1914 UU · 1970 CE Discovered 24 June 1914 | |
Named after Elena Neujmina(discoverer's family) Similar 528 Rezia, 540 Rosamunde, 779 Nina, 679 Pax, 509 Iolanda | ||
789 Lena, provisional designation 1914 UU, is an asteroid from the middle region of the asteroid belt, approximately 24 kilometers in diameter. It was discovered on 24 June 1914, by Soviet–Russian astronomer Grigory Neujmin at Simeiz Observatory on the Crimean peninsula.
The X-type asteroid is also classified as a M-type by NASA's Wide-field Infrared Survey Explorer (WISE). It orbits the Sun at a distance of 2.3–3.1 AU once every 4 years and 5 months (1,608 days). Its orbit has an eccentricity of 0.15 and an inclination of 11° with respect to the ecliptic. Although its orbital elements resemble those of the asteroids in the Eunomia family, true members of this family have a S-type composition, so it is almost certainly an unrelated interloper. Lena's first used observation was made much later at Yerkes Observatory in 1935, reducing the body's observation arc by 21 years with respect to its official discovery observation.
In 1993, a rotational light-curve which was later proven incorrect, was obtained from photometric observations at the Félix Aguilar Observatory, Argentina. It gave an unusual light-curve, indicating a very irregular shape and/or a relatively long rotation period of 22 hours with an exceptionally high amplitude of 1.5 in magnitude (U=0). In August and September 2007, two new light-curves were obtained by Italian astronomer Silvano Casulli and by members at the U.S.Oakley Observatory, and gave a period of 7000584800000000000♠5.848±0.001 and 7000585000000000000♠5.85±0.05 hours, with a brightness variation of 0.50 and of 0.40 in magnitude, respectively (U=3/2+).
According to the space-based surveys carried out by the Japanese Akari satellite and the NEOWISE mission of the WISE telescope, Lena measures between 20.6 and 23.9 kilometers in diameter, and its surface has an albedo of 0.137–0.186. The Collaborative Asteroid Lightcurve Link assumes a much lower albedo of 0.10 and calculates a diameter of 24.2 kilometer, as the lower the albedo (reflectivety), the larger a body's diameter, at a constant absolute magnitude (brightness).
The minor planet was named in honor of Elena ("Lena") Petrovna Neujmina (1860–1942), mother of the discovering astronomer.