135 Hertha
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A three-dimensional model of 135 Hertha based on its light curve.
|
|
| Discovery | |
|---|---|
| Discovered by | Christian Heinrich Friedrich Peters |
| Discovery site | Litchfield Observatory, Clinton, New York |
| Discovery date | February 18, 1874 |
| Designations | |
Main belt  Nysa |
|
| Orbital characteristics | |
| Epoch 2008-05-14 (JD 2454600.5) | |
| Aphelion | 2.9287124854 ± 4.995×10−9 AU |
| Perihelion | 1.92827931 ± 2.0509×10−7 AU |
| 2.4284958975 ± 4.1419×10−9 AU | |
| Eccentricity | 0.205977942 ± 8.4222×10−8 |
| 3.78 ± 9.682×10−9 y | |
|
Average orbital speed
|
18.91 km/s |
| 16.444645 ± 2.1094×10−5° | |
| Inclination | 2.3051442 ± 9.8708×10−6° |
| 343.84267 ± 1.901×10−4° | |
| 339.91983 ± 1.9113×10−4° | |
| Physical characteristics | |
| Dimensions | 79.24 km 76.12 ± 3.29 km |
| Mass | (1.21 ± 0.16) × 1018 kg |
|
Mean density
|
5.23 ± 0.96 g/cm3 |
| 8.40061 | |
| Albedo | 0.1436 |
|
Spectral type
|
M |
| 8.23 | |
135 Hertha is a large main-belt asteroid. Named Hertha, another name for Nerthus, a Germanic fertility goddess. It orbits among the Nysa asteroid family but its classification as an M-type asteroid does not match the more common F-type asteroid for this family, suggesting that it may be an interloper. Spectroscopic analysis indicates the possible presence of hydrated silicates indicating that 135 Hertha should possibly be reclassified from its present M-type to the proposed W-type.
Lightcurve data from Hertha indicates a flattened body, and radar observations indicate that Hertha is non-metallic. Five occultations of stars by the asteroid have been observed between 2000 and 2015.
Hertha was discovered by C. H. F. Peters on February 18, 1874, in Clinton, New York. Further observations were carried out in 1883 by W. T. Sampson and communicated to Astronomische Nachrichten on his behalf by Rear Admiral R. W. Shufeldt.
After its discovery in 1874 and subsequent observations in 1884 had established Hertha's orbit, astronomers began investigation of its physical properties. As early as 1904 G. W. Hill reported observations of Hertha's brightness indicating a variation of half a magnitude and a short period.
In October 1992 Dotto et al. performed 20 hours of observations spread over 6 nights to investigate 135 Hertha's rotational period, approximate shape, and the coordinates of its rotational axis. They were able to confirm a rotational period of 8.398 ± .001 hours as previously measured by Harris et al. published earlier in 1992. In the same study, Dotto et al. measured the asteroid's shape and rotational axis. The axes' ratios were found to be: a/b = 1.34 ± .03 and b/c = 1.22 ± .05. Two possible values were determined for the rotational axis, however further measurements at different ecliptic longitudes are required to determine which is correct.
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