225 Henrietta

225 Henrietta

Discovery
Discovered by	Johann Palisa
Discovery date	April 19, 1882
Designations
Alternative names	n/a
Minor planet category	Main belt (Cybele)
Orbital characteristics
Epoch 30 January 2005 (JD 2453400.5)
Aphelion	641.471 Gm (4.288 AU)
Perihelion	370.46 Gm (2.476 AU)
Semi-major axis	505.966 Gm (3.382 AU)
Eccentricity	0.268
Orbital period	2271.87 d (6.22 a)
Average orbital speed	16.2 km/s
Mean anomaly	215.046°
Inclination	20.902°
Longitude of ascending node	197.199°
Argument of perihelion	104.697°
Physical characteristics
Dimensions	121.0 km
Mass	unknown
Mean density	unknown
Equatorial surface gravity	unknown
Escape velocity	unknown
Rotation period	7.356 h
Albedo	.040
Temperature	unknown
Spectral type	C
Absolute magnitude (H)	8.72

225 Henrietta is a very large outer main-belt asteroid. It was discovered by Johann Palisa on April 19, 1882, in Vienna and named after Henrietta, wife of astronomer Pierre J. C. Janssen.

This is classified as a C-type asteroid and is probably composed of privitive carbonaceous material. It has 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 hours 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 hours determined in 2000.

225 Henrietta belongs to Cybele group of asteroids and is probably in a 4:7 orbital resonance with the planet Jupiter.

References

• The Asteroid Orbital Elements Database
• Minor Planet Discovery Circumstances
• Asteroid Lightcurve Data File