| Minorplanet: | yes |
| 1909 Alekhin | |
| Background: |
|
| Discovered: | 4 September 1972 |
| Mpc Name: | (1909) Alekhin |
| Alt Names: | 1926 GU 1930 KF1930 KM 1934 NZ1934 OC 1941 FJ1960 FD 1969 UU1971 DL |
| Named After: | Alexander Alekhine |
| Epoch: | 4 September 2017 (JD 2458000.5) |
| Uncertainty: | 0 |
| Observation Arc: | 91.06 yr (33,259 days) |
| Perihelion: | 1.8758 AU |
| Semimajor: | 2.4226 AU |
| Eccentricity: | 0.2257 |
| Period: | 3.77 yr (1,377 days) |
| Mean Motion: | / day |
| Inclination: | 1.7955° |
| Asc Node: | 227.46° |
| Arg Peri: | 5.6412° |
| Dimensions: | km 17.33 km km km km |
| Albedo: | 0.0446 |
| Abs Magnitude: | 12.3012.60 12.812.9 |
1909 Alekhin, provisional designation, 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, and named after chess grandmaster and World Chess Champion Alexander Alekhine.
The S-type asteroid orbits the Sun in the inner main-belt 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.
Alekhin is a slow rotator. In March 2009 and September 2010, two rotational lightcurves for Alekhin were obtained from photometric observations made by the Palomar Transient Factory and by astronomer Roger Dymock, respectively. The lightcurves gave a rotation period of 148 hours with a brightness variation of 0.42–0.45 magnitude .
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 with 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.
This minor planet was named in honour of Russian-born Alexander Alekhine (1892–1946), chess grandmaster, considered one of the greatest chess players ever. The official was published by the Minor Planet Center on 20 February 1976 .