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122 Gerda

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Main-belt asteroid

122 Gerda
Discovery
3D convex shape model of 122 Gerda
Discovered by	Christian Heinrich Friedrich Peters
Discovery date	31 July 1872
Designations
MPC designation	(122) Gerda
Pronunciation	/ˈɡɜːrdə/^[1]
Alternative designations	A872 OA;1948 TQ₁
Minor planet category	Main belt
Orbital characteristics^[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	143.71 yr (52491 d)
Aphelion	3.32884 AU (497.987 Gm)
Perihelion	3.11932 AU (466.644 Gm)
Semi-major axis	3.22408 AU (482.316 Gm)
Eccentricity	0.032493
Orbital period (sidereal)	5.79yr (2114.5d)
Averageorbital speed	16.59 km/s
Mean anomaly	163.616°
Mean motion	0° 10^m 12.911^s / day
Inclination	1.64006°
Longitude of ascending node	178.139°
Argument of perihelion	321.617°
Earth MOID	2.13107 AU (318.804 Gm)
Jupiter MOID	1.66324 AU (248.817 Gm)
T_Jupiter	3.187
Physical characteristics
Dimensions	81.69±1.9 km
Mass	5.7×10¹⁷ kg
Equatorialsurface gravity	0.0228 m/s²
Equatorialescape velocity	0.0432 km/s
Synodic rotation period	10.685 h (0.4452 d)^[2] 10.687 ± 0.001 h^[3]
Geometric albedo	0.1883±0.009
Temperature	~155K
Spectral type	S^[4]
Absolute magnitude (H)	7.87

122 Gerda is a fairly large outermain-belt asteroid that was discovered by German-American astronomerC. H. F. Peters on July 31, 1872, and named afterGerðr, the wife of the godFreyr inNorse mythology. Based upon its spectrum, this is classified as anS-type asteroid.^[4] It is listed as a member of the Hecuba group of asteroids that orbit near the 2:1mean-motion resonance withJupiter.^[5]

Photometric observations of this asteroid in 2007 were used to produce alight curve that showed that Gerda rotates every 10.687 ± 0.001 hours and varied in brightness by 0.16 inmagnitude.^[3] In 2009, observations at the Organ Mesa Observatory inLas Cruces, New Mexico generated a light curve with a period of 10.712 ± 0.01 hours with a brightness variation of 0.11 ± 0.01 magnitudes. This is compatible with previous studies.^[6]

References

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^Noah Webster (1884)A Practical Dictionary of the English Language
^^a ^bYeomans, Donald K.,"122 Gerda",JPL Small-Body Database Browser,NASA Jet Propulsion Laboratory, retrieved12 May 2016.
^^a ^bBuchheim, Robert K. (March 2007), "Lightcurves for 122 Gerda, 217 Eudora, 631 Phillipina 670 Ottegebe, and 972 Cohnia",The Minor Planet Bulletin, vol. 34, no. 1, pp. 13–14,Bibcode:2007MPBu...34...13B.
^^a ^bDevogèle, M.; Tanga, P.; Cellino, A.; Bendjoya, Ph.; Rivet, J. -P.; Surdej, J.; Vernet, D.; Sunshine, J. M.; Bus, S. J.; Abe, L.; Bagnulo, S.; Borisov, G.; Campins, H.; Carry, B.; Licandro, J.; McLean, W.; Pinilla-Alonso, N. (April 2018), "New polarimetric and spectroscopic evidence of anomalous enrichment in spinel-bearing calcium-aluminium-rich inclusions among L-type asteroids",Icarus,304:31–57,arXiv:1802.06975,Bibcode:2018Icar..304...31D,doi:10.1016/j.icarus.2017.12.026
^McDonald, Sophia Levy (June 1948), "General perturbations and mean elements, with representations of 35 minor planets of the Hecuba group",Astronomical Journal,53: 199,Bibcode:1948AJ.....53..199M,doi:10.1086/106097.
^Pilcher, Frederick (October 2009), "New Lightcurves of 8 Flora, 13 Egeria, 14 Irene, 25 Phocaea 40 Harmonia, 74 Galatea, and 122 Gerda",The Minor Planet Bulletin, vol. 36, no. 4, pp. 133–136,Bibcode:2009MPBu...36..133P.

External links

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122 Gerda atAstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
122 Gerda at theJPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

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