Astronomy:101 Helena

From HandWiki
Revision as of 04:26, 27 June 2023 by LinuxGuru (talk | contribs) (link)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Short description: Main-belt asteroid
101 Helena
Орбита астероида 101.png
Orbital diagram
Discovery
Discovered byJames Craig Watson
Discovery date15 August 1868
Designations
(101) Helena
Pronunciation/ˈhɛlənə/[1]
Named afterHelen of Troy
A868 PA
Minor planet categoryMain belt
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc145.07 yr (52986 d)
|{{{apsis}}}|helion}}2.94606 astronomical unit|AU (440.724 Gm)
|{{{apsis}}}|helion}}2.22353 AU (332.635 Gm)
2.58480 AU (386.681 Gm)
Eccentricity0.13977
Orbital period4.16 yr (1517.9 d)
Average Orbital speed18.44 km/s
Mean anomaly236.265°
Mean motion0° 14m 13.823s / day
Inclination10.1976°
Longitude of ascending node343.419°
348.030°
Earth MOID1.21369 AU (181.565 Gm)
Jupiter MOID2.4117 AU (360.79 Gm)
TJupiter3.387
Physical characteristics
Dimensions65.84±1.3 km[2]
Mass3.0×1017 kg
Mean density2.0 g/cm3
Equatorial surface gravity
0.0184 m/s2
Equatorial escape velocity
0.0348 km/s
Rotation period23.080 h (0.9617 d)[2]
Geometric albedo0.1898±0.008[2]
Physics~173 K
S[3]
Absolute magnitude (H)8.33


Helena (minor planet designation: 101 Helena) is a large, rocky main-belt asteroid. It was discovered by Canadian-American astronomer J. C. Watson on August 15, 1868,[4] and was named after Helen of Troy in Greek mythology.

This object is orbiting the Sun with a period of 4.16 years and an eccentricity of 0.14. Its orbital plane is inclined by 10.2° to the plane of the ecliptic. 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 mean diameter estimated from IRAS infrared measurements is 66 km, in agreement with the radar findings. It is classified as an S-type asteroid in the Tholen system,[3][5] suggesting a predominantly silicate composition. 101 Helena is spinning on its axis with a period of 23 hours.[2]

References

  1. Noah Webster (1884) A Practical Dictionary of the English Language
  2. 2.0 2.1 2.2 2.3 2.4 Yeomans, Donald K., "101 Helena", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=101, retrieved 12 May 2016. 
  3. 3.0 3.1 DeMeo, Francesca E. et al. (2011), "An extension of the Bus asteroid taxonomy into the near-infrared", Icarus 202 (1): 160–180, doi:10.1016/j.icarus.2009.02.005, Bibcode2009Icar..202..160D, archived from the original on 2014-03-17, https://web.archive.org/web/20140317200310/https://www.tara.tcd.ie/bitstream/2262/43276/1/PEER_stage2_10.1016/j.icarus.2009.02.005.pdf, retrieved 2013-03-22.  See appendix A.
  4. "Numbered Minor Planets 1–5000", Discovery Circumstances (IAU Minor Planet center), https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html, retrieved 2013-04-07. 
  5. 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, doi:10.1016/j.icarus.2006.08.018, Bibcode2007Icar..186..126M. 

External links