1909 Alekhin

1909 Alekhin, provisional designation 1972 RW₂, is a stony asteroid and slow rotator from the inner regions of the asteroid belt, approximately 17 kilometers in diameter. It was discovered on 4 September 1972, by Russian–Ukrainian astronomer Lyudmila Zhuravleva at the Crimean Astrophysical Observatory, Nauchnyj, on the Crimean peninsula.

The S-type asteroid orbits the Sun at a distance of 1.9–3.0 AU once every 3 years and 9 months (1,377 days). Its orbit has an eccentricity of 0.23 and an inclination of 2° with respect to the ecliptic.

In March 2009 and September 2010, two rotational light-curves for Alekhin were obtained from photometric observations made by the Palomar Transient Factory and by astronomer Roger Dymock, respectively. The light-curves gave a rotation period of 148 hours with a brightness variation of 0.42–0.45 magnitude (U=2/3). Alekhin is a slow rotator.

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, Alekhin measures between 15.5 and 18.8 kilometers in diameter and its surface has an albedo of 0.046 to 0.070. The Collaborative Asteroid Lightcurve Link derives an albedo of 0.045 and a diameter of 17.3 kilometers based on an absolute magnitude of 12.8.

Alekhin is scheduled to occlude a 9.1 magnitude star in the Leo constellation on 30 November 2008, dimming the magnitude of both heavenly bodies for a maximum duration of 0.6 seconds. Astronomers had, as of March 2008, not predicted an optimal trajectory for the event. Lyudmila Zhuravleva is ranked number 43 in Harvard's ranking of those who discovered minor planets. She discovered 200 minor planets, thirteen of which were co-discoveries, between 1972 and 1992.

The minor planet was named in honour of Russian-born Alexander Alekhine (1892–1946), chess grandmaster, considered one of the greatest chess players ever. Naming citation was published before November 1977 (M.P.C. 3937).