101 Helena

Not to be confused with Helene (moon).
101 Helena
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)
18.44 km/s
125.599°
Inclination 10.1996°
343.44°
347.34°
Physical characteristics
Dimensions 65.8[1] km
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. ↑ 1.0 1.1 1.2 1.3 Yeomans, Donald K., "101 Helena", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 2013-03-09.
    2. ↑ 2.0 2.1 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.
    3. ↑ "Numbered Minor Planets 1–5000", Discovery Circumstances (IAU Minor Planet center), retrieved 2013-04-07.
    4. ↑ 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): 126–151, Bibcode:2007Icar..186..126M, doi:10.1016/j.icarus.2006.08.018.