153 Hilda

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153 Hilda
Hilda-LB1-mag14.jpg
Star field showing Hilda (apmag 14.2)
Discovery[1] and designation
Discovered by J. Palisa
Discovery date 1875
Designations
Minor planet category Main belt (Hilda)
Orbital characteristics[1]
Aphelion 4.533 AU
Perihelion 3.412 AU
3.973 AU
Eccentricity 0.141
7.92 years
Inclination 7.83°
Physical characteristics
Dimensions 171 ± ?? km[1]
Mass ~5.2×1018 kg
Equatorial escape velocity
~ 6 m/s
5.11 hours[1]
0.062[1]
C
7.48[1]
A schematic of the orbit of 153 Hilda (green), with Jupiter (red). The open red circles are the Jovian Lagrange points that Hilda approaches.[note 1]

153 Hilda is a large asteroid in the outer main belt, with a diameter of 170 km.[1] Because it is composed of primitive carbonaceous materials, it has a very dark surface. It was discovered by Johann Palisa on November 2, 1875 from the Austrian Naval Observatory at Pula.[1] The name was chosen by the astronomer Theodor von Oppolzer, who named it after one of his daughters.[2]

Orbit and family[edit]

Hilda gives its name to an asteroid group called the Hilda family (or Hildas for short). It is not a true asteroid family, since the members are not physically related, but rather share similar orbital elements. The Hildas are locked in a 2:3 orbital resonance with Jupiter;[3] since Jupiter takes 11.9 years to orbit the Sun while Hilda takes 7.9 years,[1] Jupiter orbits the Sun twice for every 3 orbits that Hilda completes. There are over 1,100 other objects known to be in a 2:3 resonance with Jupiter.[3]

Observations[edit]

Hilda was observed to occult a star on December 31, 2002, from Japan. It has a very low-amplitude light curve indicating a spherical body or a non-varying albedo.[citation needed]

Notes[edit]

  1. ^ Based on orbital data from the year 2000. Hilda seldom approaches the Lagrangians exactly.

References[edit]

  1. ^ a b c d e f g h i "JPL Small-Body Database Browser: 153 Hilda". 1998-02-12 last obs. Retrieved 2009-12-15. 
  2. ^ Lutz D. Schmadel, Dictionary of Minor Planet Names, p.29.
  3. ^ a b Brož, M.; Vokrouhlický, D. (2008). "Asteroid families in the first-order resonances with Jupiter". Monthly Notices of the Royal Astronomical Society 390 (2): 715–732. Bibcode:2008MNRAS.tmp.1068B. doi:10.1111/j.1365-2966.2008.13764.x. 

External links[edit]