122 Gerda
Gerda (minor planet designation: 122 Gerda) is a fairly large outer main-belt asteroid that was discovered by German-American astronomer C. H. F. Peters on July 31, 1872, and named after Gerðr, the wife of the god Freyr in Norse mythology. Based upon its spectrum, this is classified as an S-type asteroid. It is listed as a member of the Hecuba group of asteroids that orbit near the 2:1 mean-motion resonance with Jupiter.
3D convex shape model of 122 Gerda | |
| Discovery | |
|---|---|
| Discovered by | Christian Heinrich Friedrich Peters |
| Discovery date | 31 July 1872 |
| Designations | |
MPC designation | (122) Gerda |
| Pronunciation | /ˈɡɜːrdə/ |
Alternative designations | A872 OA; 1948 TQ1 |
Minor planet category | Main belt |
| Orbital characteristics | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 143.71 yr (52491 d) |
| Aphelion | 3.32884 AU (497.987 Gm) |
| Perihelion | 3.11932 AU (466.644 Gm) |
Semi-major axis | 3.22408 AU (482.316 Gm) |
| Eccentricity | 0.032493 |
Orbital period (sidereal) | 5.79 yr (2114.5 d) |
Average orbital speed | 16.59 km/s |
Mean anomaly | 163.616° |
Mean motion | 0° 10m 12.911s / day |
| Inclination | 1.64006° |
Longitude of ascending node | 178.139° |
| 321.617° | |
| Earth MOID | 2.13107 AU (318.804 Gm) |
| Jupiter MOID | 1.66324 AU (248.817 Gm) |
| TJupiter | 3.187 |
| Physical characteristics | |
| Dimensions | 81.69±1.9 km |
| Mass | 5.7×1017 kg |
Equatorial surface gravity | 0.0228 m/s2 |
Equatorial escape velocity | 0.0432 km/s |
Synodic rotation period | 10.685 h (0.4452 d) 10.687 ± 0.001 h |
| 0.1883±0.009 | |
| Temperature | ~155 K |
| S | |
| 7.87 | |
Photometric observations of this asteroid in 2007 were used to produce a light curve that showed that Gerda rotates every 10.687 ± 0.001 hours and varied in brightness by 0.16 in magnitude. In 2009, observations at the Organ Mesa Observatory in Las Cruces, New Mexico generated a light curve with a period of 10.712 ± 0.01 hours with a brightness variation of 0.11 ± 0.01 magnitudes. This is compatible with previous studies.