Roberta (minor planet designation: 335 Roberta) is a large main belt asteroid. It was discovered on 1 September 1892, by German astronomer Anton Staus at Heidelberg Observatory.[3] Roberta was the 12th asteroid that was discovered using photography, and the only asteroid discovery made by Staus.[4]
| Discovery | |
|---|---|
| Discovered by | Anton Staus |
| Discovery date | 1 September 1892 |
| Designations | |
MPC designation | (335) Roberta |
Named after | Carl Robert Osten-Sacken |
Alternative designations | 1892 C |
Minor planet category | Main belt |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 123.58 yr (45137 d) |
| Aphelion | 2.9014 AU (434.04 Gm) |
| Perihelion | 2.04926 AU (306.565 Gm) |
Semi-major axis | 2.47530 AU (370.300 Gm) |
| Eccentricity | 0.17212 |
Orbital period (sidereal) | 3.89 yr (1422.5 d) |
Average orbital speed | 18.93 km/s |
Mean anomaly | 355.460° |
Mean motion | 0° 15m 11.095s / day |
| Inclination | 5.1005° |
Longitude of ascending node | 148.454° |
Argument of perihelion | 140.006° |
| Earth MOID | 1.03587 AU (154.964 Gm) |
| Jupiter MOID | 2.2733 AU (340.08 Gm) |
| TJupiter | 3.456 |
| Physical characteristics | |
| Dimensions | 89.07±2.0 km[1] |
Synodic rotation period | 12.054 h (0.5023 d) |
Geometric albedo | 0.0580±0.003[1] 0.058[2] |
Spectral type | B–V = 0.624 U–B = 0.235 FP (Tholen) B (SMASS)[1] |
Absolute magnitude (H) | 8.96[1] |
Photometric observations of this asteroid from multiple sites during 2007 gave a light curve with a period of 12.054 ± 0.003 hours and a brightness variation of 0.13 ± 0.02 in magnitude. This agrees with a result reported in 1992, but differs from period estimates of 8.03 hours and 4.349 reported in 1987 and 2001, respectively.[5]
Under the SMASS classification taxonomy, this asteroid is listed as a B-type; a group that combines both the Tholen B and F types. The spectrum of this object suggests the presence of magnetite (Fe3O4), which gives it the spectrally-blue coloration that is a characteristic of this SMASS class. The spectrum of this asteroid also displays a band feature near 2.9 μm that indicate the presence of a hydrated mineral. This suggests that the asteroid has undergone significant water-based alteration.[2]
335 Roberta was identified as one of three asteroids that were likely to be a parent body for chondrites along with 449 Hamburga and 304 Olga.[6] All three asteroids were known to have low-albedo (not reflect as much light) and be close to "meteorite producing resonances".[6] Chrondrites are the most common type of meteor found on Earth, accounting for over 80% of all meteors.[7] They are named for the tiny spherical silicate particles that are found inside them (those particles are called chondrules).[7]
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