11665 Dirichlet is a numbered minor planet (asteroid) located in the main asteroid belt between the orbits of Mars and Jupiter. It was discovered on 22 March 1995 by the Belgian astronomer Eric W. Elst at the La Silla Observatory in Chile. The asteroid received its permanent numerical designation (11665) after the confirmation of its orbit, and it was later named in honor of the German mathematician Johann Peter Gustav Lejeune Dirichlet (1805 – 1859), whose contributions to number theory, analysis, and mathematical physics are well documented.
Orbital characteristics (as of the latest epoch data):
- Orbit classification: Main‑belt asteroid
- Semi‑major axis: Approximately 2.7 AU (astronomical units)
- Eccentricity: About 0.12, indicating a modestly elliptical orbit
- Orbital period: Roughly 4.4 years (≈ 1 603 days)
- Inclination: Near 5° to the ecliptic plane
Physical properties:
- Absolute magnitude (H): 13.5 ± 0.3, suggesting a diameter in the range of 6–10 km depending on albedo assumptions.
- Spectral type: Not yet classified; most main‑belt asteroids of similar size belong to the C‑type (carbonaceous) or S‑type (silicaceous) families.
Naming citation:
The naming citation was published by the Working Group for Small Body Nomenclature of the International Astronomical Union (IAU) on 30 March 2005. It recognizes Dirichlet’s foundational work, including Dirichlet’s theorem on arithmetic progressions, the Dirichlet principle, and his influence on the development of modern analysis and number theory.
Observational history:
Since its discovery, 11665 Dirichlet has been observed at multiple oppositions, allowing refinement of its orbital elements. It is not known to be part of any identified asteroid family, nor is it currently classified as a near‑Earth object or a potentially hazardous asteroid.
References:
- Minor Planet Center (MPC) database, object 11665.
- JPL Small‑Body Database, 11665 Dirichlet.
- “Dictionary of Minor Planet Names” (Lutz D. Schmadel, 2003).
