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225 Henrietta

Orbital diagram
Discovery
Discovered by	Johann Palisa
Discovery date	19 April 1882
Designations
MPC designation	(225) Henrietta
Pronunciation	/hɛnriˈɛtə/
Named after	Henrietta Jansen
Alternative designations	A882 HA
Minor planet category	Main belt (Cybele)
Orbital characteristics
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	120.87 yr (44,148 d)
Aphelion	4.28364 AU (640.823 Gm)
Perihelion	2.4945 AU (373.17 Gm)
Semi-major axis	3.38907 AU (506.998 Gm)
Eccentricity	0.26396
Orbital period (sidereal)	6.24 yr (2,278.9 d)
Average orbital speed	16.2 km/s
Mean anomaly	159.155°
Mean motion	0° 9 28.703 / day
Inclination	20.872°
Longitude of ascending node	197.113°
Argument of perihelion	104.149°
Physical characteristics
Dimensions	120.49±2.5 km
Synodic rotation period	7.3556 h (0.30648 d)
Geometric albedo	0.0396±0.002
Spectral type	C
Absolute magnitude (H)	8.72

225 Henrietta is a very large outer main-belt asteroid. It was discovered by Austrian astronomer Johann Palisa on April 19, 1882, in Vienna and named after Henrietta, wife of astronomer Pierre J. C. Janssen. The asteroid is orbiting at a distance of 3.39 AU from the Sun with a period of 6.24 years and an eccentricity (ovalness) of 0.26. The orbital plane is inclined at an angle of 20.9° to the plane of the ecliptic. 225 Henrietta belongs to Cybele group of asteroids and is probably in a 4:7 orbital resonance with the planet Jupiter.

This is classified as a C-type asteroid and is probably composed of primitive carbonaceous material. It has a very dark surface, with an albedo of 0.040. Photometric measurements made from the Oakley Southern Sky Observatory during 2012 gave a light curve with a period of 7.352±0.003 h and a variation in brightness of 0.18±0.02 in magnitude. This is consistent with a synodic rotation period of 7.356±0.001 h determined in 2000. In 2001, the asteroid was detected by radar from the Arecibo Observatory at a distance of 1.58 AU. The resulting data yielded an effective diameter of 128±16 km.

References

1. ^ "225 Henrietta". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 12 May 2016.
2. Schmadel, Lutz D. (2007). "(225) Henrietta". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 35. doi:10.1007/978-3-540-29925-7_226. ISBN 978-3-540-00238-3.
3. Kasuga, Toshihiro; et al. (June 2012). "AKARI/AcuA Physical Studies of the Cybele Asteroid Family". The Astronomical Journal. 143 (6): 11. Bibcode:2012AJ....143..141K. CiteSeerX 10.1.1.430.9746. doi:10.1088/0004-6256/143/6/141. S2CID 121131179. 141.
4. Moravec, Patricia; Cochren, Joseph; Gerhardt, Michael; et al. (October 2012), "Asteroid Lightcurve Analysis at the Oakley Southern Sky Observatory: 2012 January-April", The Minor Planet Bulletin, 39 (4): 213–216, Bibcode:2012MPBu...39..213M.
5. Magri, Christopher; et al. (January 2007), "A radar survey of main-belt asteroids: Arecibo observations of 55 objects during 1999 2003" (PDF), Icarus, 186 (1): 126–151, Bibcode:2007Icar..186..126M, doi:10.1016/j.icarus.2006.08.018, retrieved 14 April 2015.

External links

• The Asteroid Orbital Elements Database
• Minor Planet Discovery Circumstances
• Asteroid Lightcurve Data File
• 225 Henrietta at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 225 Henrietta at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

• Minor planet object articles (numbered)
• F-type asteroids (Tholen)
• Cybele asteroids
• Discoveries by Johann Palisa
• Named minor planets
• Astronomical objects discovered in 1882