29 Amphitrite

Amphitrite (minor planet designation: 29 Amphitrite) is one of the largest S-type asteroids, approximately 200 kilometers (120 miles) in diameter, and probably fifth largest after Eunomia, Juno, Iris and Herculina.

29 Amphitrite
VLT image of Amphitrite
Discovery [1]
Discovered byA. Marth
Discovery siteLondon
Discovery date1 March 1854
Designations
(29) Amphitrite
Pronunciation/æmfɪˈtrt/[2]
Named after
Amphitrite[3]
(Greek mythology)
A899 NG
main-belt[1][4] · (middle)
background[5][6]
AdjectivesAmphitritean /ˌæmfɪtrɪˈtən/, /ˌæmfɪˈtrtiən/
Symbol (historical)
Orbital characteristics[4]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc162.83 yr (59,472 d)
Aphelion2.7400 AU
Perihelion2.3712 AU
2.5556 AU
Eccentricity0.0722
4.09 yr (1,492 d)
187.97°
0° 14m 28.68s / day
Inclination6.0823°
356.37°
63.036°
Physical characteristics
Dimensions233 km × 212 km × 193 km[7]
Mean diameter
204±2 km[8]
189.6±1.1 km[9]
196±22 km[10]
206.86 km[11]
212.22±6.8 km[12]
227.1±4.0 km[13]
Flattening0.18[a]
Mass(12.7±2.0)×1018 kg[8]
(11.8±?)×1018 kg[7]
Mean density
2.86±0.45 g/cm3[8]
2.36±0.26 g/cm3[7]
5.3921 h[14][6]
0.194[8]
0.157±0.035[13]
0.1793±0.012[12]
0.195[11]
0.216±0.043[9]
S[6]
5.85[1]
5.99[4]
6.0[5]

Discovery

Amphitrite was discovered by Albert Marth on 1 March 1854, at the private South Villa Observatory, in Regent's Park, London. It was Marth's only asteroid discovery. Its name was chosen by George Bishop, the owner of the observatory, who named it after Amphitrite, a sea goddess in Greek mythology.[3] Its historical symbol was a shell and star; it is in the pipeline for Unicode 17.0 as U+1CECF 𜻏 ( ).[15][16]

Characteristics

Lightcurve-based 3D-model of Amphitrite

Amphitrite's orbit is less eccentric and inclined than those of its larger cousins; indeed, it is the most circular of any asteroid discovered up to that point. As a consequence, it never becomes as bright as Iris or Hebe, especially as it is much further from the Sun than those asteroids. It can reach magnitudes of around +8.6 at a favorable opposition, but usually is around the binocular limit of +9.5.

In 2007, James Baer and Steven R. Chesley estimated Amphitrite to have a mass of 1.9×1019 kg.[17] A more recent estimate by Baer suggests it has a mass of 1.18×1019 kg.[7]

A satellite of the asteroid is suspected to exist, based on lightcurve data collected by Edward F. Tedesco.[18][19] In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but neither were found.[20]

Notes

References