153 Hilda

153 Hilda
	Star field showing Hilda (apmag 14.2)
Discovery
Discovered by	J. Palisa
Discovery site	Austrian Naval Obs.
Discovery date	2 November 1875
Designations
MPC designation	(153) Hilda
Pronunciation	/ˈhɪldə/
Minor planet category	Main belt (Hilda)
Adjectives	Hildian /ˈhɪldiən/
Orbital characteristics
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	121.05 yr (44215 d)
Aphelion	4.5341 AU (678.29 Gm)
Perihelion	3.4225 AU (512.00 Gm)
Semi-major axis	3.9783 AU (595.15 Gm)
Eccentricity	0.13971
Orbital period (sidereal)	7.94 yr (2898.3 d)
Mean anomaly	51.690°
Mean motion	0° 7m 27.156s / day
Inclination	7.8249°
Longitude of ascending node	228.16°
Argument of perihelion	38.617°
Jupiter MOID	0.569657 AU (85.2195 Gm)
TJupiter	3.023
Physical characteristics
Dimensions	170.63±3.3 km
Mass	~5.2×1018 kg
Equatorial escape velocity	~ 6 m/s
Synodic rotation period	5.9587 h (0.24828 d)
Geometric albedo	0.0618±0.002
Spectral type	C
Absolute magnitude (H)	7.48

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]

Orbit and family[]

File:HildasOrbitWithLagrangePointsLousy.ogv

Play media

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]}

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[]

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

References[]

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

External links[]

The triangle formed by the Hilda asteroids EasySky
153 Hilda at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
153 Hilda at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

[5] Based on orbital data from the year 2000. Hilda seldom approaches the Lagrangians exactly.

[jpldata-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ "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.

[Broz2008-6] 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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