101 Helena

Main-belt asteroid Helene (moon) October 2019 yes #D6D6D6 101 Helena Орбита астероида 101.png Orbital diagram James Craig Watson 15 August 1868 (101) Helena A868 PA ' h ɛ l ə n əNoah Webster (1884) A Practical Dictionary of the English Language Helen of Troy Main belt 31 July 2016 (JD 2457600.5) 2.58480 AU Gm on 2.22353 AU Gm on 2.94606 AU Gm on on 0.13977 4.16 yr (1517.9 d) 10.1976° 343.419° 348.030° 236.265° 18.44 km/s 65.84 1.3 km 3.017 kg 2.0 g/cm3 0.0184 m/s2 0.0348 km/s 23.080 h d on on S 8.33 0.1898 0.008 ~173 K 0.237173 ms / day 145.07 yr (52986 d) 0 1.21369 AU Gm on 2.4117 AU Gm on 3.387 101 Helena is a large, rocky main-belt asteroid. It was discovered by Canadian-American astronomer J. C. Watson on August 15, 1868, 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, suggesting a predominantly silicate composition. 101 Helena is spinning on its axis with a period of 23 hours. References Numbered Minor Planets 1–5000 Discovery Circumstances IAU Minor Planet center https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html 2013-04-07 . Donald K. Yeomans 101 Helena JPL Small-Body Database Browser NASA Jet Propulsion Laboratory https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=101 https://web.archive.org/web/20140924202533/http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=101 dead 24 September 2014 12 May 2016 . Christopher Magri Michael C. Nolan Steven J. Ostro Jon D. Giorgini A radar survey of main-belt asteroids: Arecibo observations of 55 objects during 1999 2003 Icarus 186 1 126–151 January 2007 10.1016/j.icarus.2006.08.018 2007Icar..186..126M . Francesca E. DeMeo Richard P. Binzel Stephen M. Slivan Schelte J. Bus 1 An extension of the Bus asteroid taxonomy into the near-infrared Icarus 202 1 160–180 2011 10.1016/j.icarus.2009.02.005 2009Icar..202..160D http://www.tara.tcd.ie/bitstream/2262/43276/1/PEER_stage2_10.1016%252Fj.icarus.2009.02.005.pdf 2013-03-22 . dead 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 2014-03-17 See appendix A. External links 101 100 Hekate 101 102 Miriam 000101 Category:Discoveries by James Craig Watson Category:Named minor planets 000101 000101 18680815 Category:Helen of Troy