176 Iduna
Iduna (minor planet designation: 176 Iduna) is a large main-belt asteroid that was discovered by German-American astronomer Christian Heinrich Friedrich Peters on October 14, 1877, in Clinton, New York. It is named after Sällskapet Idun, a club in Stockholm that hosted an astronomical conference; Idun (Iðunn, Iduna) is also a Norse goddess. A G-type asteroid, it has a composition similar to that of the largest main-belt asteroid, 1 Ceres.
3D convex shape model of 176 Iduna | |
| Discovery | |
|---|---|
| Discovered by | C. H. F. Peters |
| Discovery date | 14 October 1877 |
| Designations | |
MPC designation | (176) Iduna |
| Pronunciation | /iːˈduːnə/ |
Named after | Iðunn |
Alternative designations | A877 TB; 1945 RQ |
Minor planet category | Main belt |
| Orbital characteristics | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 138.50 yr (50587 d) |
| Aphelion | 3.7235 AU (557.03 Gm) |
| Perihelion | 2.6526 AU (396.82 Gm) |
Semi-major axis | 3.1880 AU (476.92 Gm) |
| Eccentricity | 0.16796 |
Orbital period (sidereal) | 5.69 yr (2079.1 d) |
Mean anomaly | 165.15° |
Mean motion | 0° 10m 23.34s / day |
| Inclination | 22.660° |
Longitude of ascending node | 200.50° |
| 188.17° | |
| Earth MOID | 1.65682 AU (247.857 Gm) |
| Jupiter MOID | 1.73015 AU (258.827 Gm) |
| TJupiter | 3.056 |
| Physical characteristics | |
| Dimensions | 121.04±2.2 km |
Synodic rotation period | 11.2877 h (0.47032 d) 11.289 hours |
| 0.0834±0.003 | |
| G | |
| 8.2 | |
An occultation of a star by Iduna was observed from Mexico on January 17, 1998.
Photometric observations of this asteroid at the Romer Observatory in Aarhus, Denmark during 1996 gave a light curve with a period of 11.289 ± 0.006 hours and a brightness variation of 0.35 in magnitude. A 2008 study at the Palmer Divide Observatory in Colorado Springs, Colorado gave a period of 11.309 ± 0.005 hours, confirming the 1996 result.