123 Brunhild

123 Brunhild
Discovery
Discovered by	Christian Heinrich Friedrich Peters
Discovery date	31 July 1872
Designations
MPC designation	(123) Brunhild
Pronunciation	/ˈbruːnhɪld/
Named after	Brynhildr
Alternative designations	A872 OB
Minor planet category	Main belt
Orbital characteristics
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	143.71 yr (52490 days)
Aphelion	3.0183 AU (451.53 Gm)
Perihelion	2.37594 AU (355.436 Gm)
Semi-major axis	2.69710 AU (403.480 Gm)
Eccentricity	0.11907
Orbital period (sidereal)	4.43 yr (1617.9 d)
Average orbital speed	18.08 km/s
Mean anomaly	96.8286°
Mean motion	0° 13m 21.054s / day
Inclination	6.4142°
Longitude of ascending node	307.834°
Argument of perihelion	125.960°
Earth MOID	1.39621 AU (208.870 Gm)
Jupiter MOID	2.22588 AU (332.987 Gm)
TJupiter	3.350
Physical characteristics
Dimensions	48 km
Mean radius	23.985±1.3 km
Mass	1.2×1017 kg (assumed)
Equatorial surface gravity	0.0134 m/s2
Equatorial escape velocity	0.0254 km/s
Synodic rotation period	10.04 h (0.418 d)
Geometric albedo	0.2134±0.026
Temperature	~170 K
Spectral type	S
Apparent magnitude	11.77 to 14.88
Absolute magnitude (H)	8.9

123 Brunhild is a stony S-type main-belt asteroid. It was discovered by German-American astronomer C. H. F. Peters on July 31, 1872, and named after Brünnehilde, a Valkyrie in Norse mythology. Brunhild has been mistaken for the non-existent variable star KN Gem.^[3]

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In 1983, 123 Brunhild was observed photometrically from the Observatoire de Haute-Provence, producing an irregular light curve that showed eight extremes, including two minima and two maxima that were more accentuated than the others. This curve indicates an irregular shape or possibly areas with higher albedo, with a rotation period of 10.04 ± 0.02 hours and a brightness variation of 0.16 ± 0.01 in magnitude.^[4]

Based upon IRAS observations, the estimated diameter of this asteroid is 47.97 ± 2.6 km with a geometric albedo of 0.2134 ± 0.026.^[2] A smaller diameter value of 41.33 ± 1.73 km is obtained from the Midcourse Space Experiment observations, with an accordingly higher albedo of 0.2886 ± 0.0247.^[5]

[1]
Benjamin Smith (1903) The Century Dictionary and Cyclopedia
[2]
Yeomans, Donald K., "123 Brunhild", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 30 April 2016.
[3]
"The International Variable Star Index: KN Gem". American Association of Variable Star Observers (AAVSO). Retrieved 31 December 2011.
[4]
Barucci, M. A.; di Martino, M. (July 1984), "Rotational rates of very small asteroids - 123 Brunhild, 376 Geometria, 437 Rhodia and 1224 Fantasia", Astronomy and Astrophysics Supplement Series, 57: 103–106, Bibcode:1984A&AS...57..103B.
[5]
Tedesco, Edward F.; et al. (July 2002), "The Midcourse Space Experiment Infrared Minor Planet Survey", The Astronomical Journal, 124 (124): 583–591, Bibcode:2002AJ....124..583T, doi:10.1086/340960, S2CID 117767351.