153 Hilda

Hilda (minor planet designation: 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 2 November 1875, from the Austrian Naval Observatory at Pula, now Croatia.[1] The name was chosen by the astronomer Theodor von Oppolzer, who named it after one of his daughters.[4]

153 Hilda
Star field showing Hilda (apmag 14.2)
Discovery[1]
Discovered byJ. Palisa
Discovery siteAustrian Naval Obs.
Discovery date2 November 1875
Designations
(153) Hilda
Pronunciation/ˈhɪldə/[2]
Main belt (Hilda)
AdjectivesHildian /ˈhɪldiən/[3]
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc121.05 yr (44215 d)
Aphelion4.5341 AU (678.29 Gm)
Perihelion3.4225 AU (512.00 Gm)
3.9783 AU (595.15 Gm)
Eccentricity0.13971
7.94 yr (2898.3 d)
51.690°
0° 7m 27.156s / day
Inclination7.8249°
228.16°
38.617°
Jupiter MOID0.569657 AU (85.2195 Gm)
TJupiter3.023
Physical characteristics
Dimensions170.63±3.3 km[1]
Mass~5.2×1018 kg
Equatorial escape velocity
~ 6 m/s
5.9587 h (0.24828 d)[1]
0.0618±0.002[1]
C
7.48[1]

    Orbit and family

    Hilda gives its name to an asteroid group called the Hilda group (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;[5] 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.[5]

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

    References
    1. "JPL Small-Body Database Browser: 153 Hilda". 12 February 1998. Retrieved 12 May 2016.
    2. "Hilda". Dictionary.com Unabridged. Random House.
    3. Bhattacharya & Lichtman (2016) Solar Planetary Systems, p. 6
    4. Schmadel, Lutz D. (2003). Dictionary of Minor Planet Names. Springer Science & Business Media. p. 29. ISBN 978-3-540-00238-3.
    5. 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. arXiv:1104.4004. Bibcode:2008MNRAS.390..715B. doi:10.1111/j.1365-2966.2008.13764.x.

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