(6731) Hiei Main-belt Asteroid
Discovered on 24 January 1992 by Kushida, Y., Muramatsu, O. at Yatsugatake.
Named in honor of Eijiro Hiei (b. 1931), professor at Meisei University and professor emeritus of the National Astronomical Observatory of Japan. A solar physicist best known for his research on white-light flares, Hiei was the fourth director (1982-1992) of the Norikura Solar Observatory, where he conducted coronagraphic studies. Name proposed by the discoverers following a suggestion by T. Sakurai.Naming citation (19961026/MPCPages.arc), IAU / Minor Planet Center, via NASA/JPL
Where Hiei is today
Seen from above the solar system on 2026-10-14: Hiei is 2.38 au from the Sun and 3.32 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 6731 |
| Provisional designation | 1992 BK |
| Orbit class | Main-belt Asteroid |
| Diameter | 7.98 km (#6,597 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.0920 |
| Absolute magnitude (H) | 14.16 |
| Orbital period | 4.28 years |
| Semi-major axis | 2.64 au |
| Perihelion – aphelion | 2.02 – 3.25 au |
| Eccentricity | 0.234 |
| Inclination | 4.17° |
| Closest distance between its orbit and Earth's (MOID) | 1.04 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.