101 Helena
Not to be confused with Helene (moon).
| Discovery | |
|---|---|
| Discovered by | James Craig Watson |
| Discovery date | 15 August 1868 |
| Designations | |
Named after | Helen of Troy |
| Main belt | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 145.07 yr (52986 d) |
| Aphelion | 2.94606 AU (440.724 Gm) |
| Perihelion | 2.22353 AU (332.635 Gm) |
| 2.58480 AU (386.681 Gm) | |
| Eccentricity | 0.13977 |
| 4.16 yr (1517.9 d) | |
Average orbital speed | 18.44 km/s |
| 236.265° | |
| 0° 14m 13.823s / day | |
| Inclination | 10.1976° |
| 343.419° | |
| 348.030° | |
| Earth MOID | 1.21369 AU (181.565 Gm) |
| Jupiter MOID | 2.4117 AU (360.79 Gm) |
| Jupiter Tisserand parameter | 3.387 |
| Physical characteristics | |
| Dimensions | 65.84±1.3 km[1] |
| Mass | 3.0×1017 kg |
Mean density | 2.0 g/cm³ |
Equatorial surface gravity | 0.0184 m/s² |
Equatorial escape velocity | 0.0348 km/s |
| 23.080 h (0.9617 d)[1] | |
| 0.1898±0.008[1] | |
| Temperature | ~173 K |
| 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 12 May 2016.
- 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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