522 Helga

522 Helga

Discovery
Discovered by	Max Wolf
Discovery site	Heidelberg Observatory
Discovery date	10 January 1904
Designations
MPC designation	(522) Helga
Pronunciation	German: [ˈhɛlɡaː][1]
Alternative designations	1904 NC
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	114.65 yr (41876 d)
Aphelion	3.9372 AU (589.00 Gm)
Perihelion	3.3284 AU (497.92 Gm)
Semi-major axis	3.6328 AU (543.46 Gm)
Eccentricity	0.083794
Orbital period (sidereal)	6.92 yr (2529.1 d)
Mean anomaly	200.06°
Mean motion	0° 8^m 32.424^s / day
Inclination	4.4174°
Longitude of ascending node	116.683°
Argument of perihelion	246.503°
Physical characteristics
Mean radius	50.61±1.75 km
Synodic rotation period	8.129 h (0.3387 d)
Geometric albedo	0.0388±0.003
Absolute magnitude (H)	9.0

522 Helga, provisional designation 1904 NC is a large main belt asteroid (minor planet). It was discovered in 1904 by Max Wolf in Heidelberg. Helga is notable for being the first such object to be shown to be in a stable but chaotic orbit in resonance with Jupiter, its Lyapunov time being relatively short, at 6,900 yr. Despite this, its orbit appears to be stable, as the eccentricity and precession rates are such that it avoids close encounters with Jupiter.^[3] It forms part of the Cybele asteroid group.^[4]

522 Helga was "named by Lt. Th. Lassen, orbit computer" according to Paul Herget's The Names of the Minor Planets^[5] (note that computer does not refer to a personal computer, i.e. a machine, but rather to a person actually doing the necessary calculations).

References

1. (German Names)
2. "522 Helga (1904 NC)". JPL Small-Body Database. NASA/Jet Propulsion Laboratory. Retrieved 6 May 2016.
3. Milani, Andrea; Nobili, Anna M. (June 1992). "An example of stable chaos in the Solar System". Nature. 357 (6379): 569–571. Bibcode:1992Natur.357..569M. doi:10.1038/357569a0. ISSN 1476-4687. S2CID 4367823.
4. Lagerkvist, Claes-Ingvar; et al. (January 2001), "A Study of Cybele Asteroids. I. Spin Properties of Ten Asteroids", Icarus, 149 (1): 190–197, Bibcode:2001Icar..149..190L, doi:10.1006/icar.2000.6507.
5. Title: Benennung von kleinen Planeten; Journal: Astronomische Nachrichten, volume 169, p.363; Bibliographic Code: 1905AN....169..363.

External links

• 522 Helga at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 522 Helga at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters