101 Helena
Not to be confused with Helene (moon).
| Discovery | |
|---|---|
| Discovered by | James Craig Watson |
| Discovery date | August 15, 1868 |
| Designations | |
Named after | Helen of Troy |
| Main belt | |
| Orbital characteristics[1] | |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 441.092 Gm (2.949 AU) |
| Perihelion | 331.683 Gm (2.217 AU) |
| 386.387 Gm (2.583 AU) | |
| Eccentricity | 0.1410 |
| 1516.67 d (4.15 a) | |
Average orbital speed | 18.44 km/s |
| 125.599° | |
| Inclination | 10.1996° |
| 343.44° | |
| 347.34° | |
| Physical characteristics | |
| Dimensions | 65.8 km[1] |
| Mass | 3.0×1017 kg |
Mean density | 2.0 g/cm³ |
| 0.0184 m/s² | |
| 0.0348 km/s | |
| 23.080[1] h | |
| Albedo | 0.1898[1] |
| Temperature | ~173 K |
Spectral type | S[2] |
| 8.33 | |
|
| |
101 Helena is a rocky main-belt asteroid. It was discovered by Canadian-American astronomer J. C. Watson on August 15, 1868,[3] and was named after Helen of Troy in Greek mythology. Radar observations were made of this object on Oct 7 and 19, 2001 from the Arecibo Observatory. Analysis of the data gave an estimated ellipsoidal diameter of 71×63×63 ± 16% km. The diameter estimated from IRAS infrared measurements is 66 km. It is classified as an S-type asteroid in the Tholen system.[2][4]
References
- 1 2 3 4 Yeomans, Donald K., "101 Helena", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 2013-03-09.
- 1 2 DeMeo, Francesca E.; et al. (2011), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus 202 (1): 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, retrieved 2013-03-22. See appendix A.
- ↑ "Numbered Minor Planets 1–5000", Discovery Circumstances (IAU Minor Planet center), retrieved 2013-04-07.
- ↑ Magri, Christopher; Nolan, Michael C.; Ostro, Steven J.; Giorgini, Jon D. (January 2007), "A radar survey of main-belt asteroids: Arecibo observations of 55 objects during 1999 2003", Icarus 186 (1), pp. 126–151, Bibcode:2007Icar..186..126M, doi:10.1016/j.icarus.2006.08.018.
External links
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