Discovery [1] | |
---|---|
Discovered by | Stephen P. Synnott and Voyager Imaging Team |
Discovery date | July 1989 |
Designations | |
Designation | Neptune V |
Pronunciation | /dəˈspaɪnə, dəˈspiːnə, dɛ-/ |
Named after | Δέσποινα Despœna |
Adjectives | Despinian |
Orbital characteristics [2] [3] | |
Epoch 18 August 1989 | |
52 525.95 km | |
Eccentricity | 0.00038 ± 0.00016 |
0.33465551 ± 0.00000001 d | |
Inclination |
|
Satellite of | Neptune |
Physical characteristics | |
Dimensions | (180±6) × (148±12) × (128±6) km [4] |
75±3 km [4] | |
Volume | ~1.8×106 km3 [a] |
Mass | ~(0.71–1.4)×1018 kg [b] |
Mean
density | 0.4–0.8 g/cm3 [5] |
~0.006–0.023 m/s2 [c] | |
~0.032–0.054 km/s [d] | |
synchronous | |
zero | |
Albedo | 0.09 [4] [6] |
Temperature | ~51 K mean (estimate) |
22.0 [6] | |
Despina /dɛˈspaɪnə/, also known as Neptune V, is the third-closest inner moon of Neptune. It is named after Greek mythological character Despoina, a nymph who was a daughter of Poseidon and Demeter.
Despina was discovered in late July 1989 from the images taken by the Voyager 2 probe. It was given the temporary designation S/1989 N 3. [7] The discovery was announced (IAUC 4824) on 2 August 1989, and mentions "10 frames taken over 5 days", implying a discovery date of sometime before July 28. The name was given on 16 September 1991. [8]
Despina's diameter is approximately 150 kilometres (93 mi). [4] Despina is irregularly shaped and shows no sign of any geological modification. It is likely that it is a rubble pile re-accreted from fragments of Neptune's original satellites, which were disrupted by perturbations from Triton soon after that moon's capture into a very eccentric initial orbit. [9]
Despina's orbit lies close to but outside of the orbit of Thalassa and just inside the Le Verrier ring and acts as its shepherd moon. [10] As it is also below Neptune's synchronous orbit radius, it is slowly spiralling inward due to tidal deceleration and may eventually impact Neptune's atmosphere, or break up into a planetary ring upon passing its Roche limit due to tidal stretching.
Discovery [1] | |
---|---|
Discovered by | Stephen P. Synnott and Voyager Imaging Team |
Discovery date | July 1989 |
Designations | |
Designation | Neptune V |
Pronunciation | /dəˈspaɪnə, dəˈspiːnə, dɛ-/ |
Named after | Δέσποινα Despœna |
Adjectives | Despinian |
Orbital characteristics [2] [3] | |
Epoch 18 August 1989 | |
52 525.95 km | |
Eccentricity | 0.00038 ± 0.00016 |
0.33465551 ± 0.00000001 d | |
Inclination |
|
Satellite of | Neptune |
Physical characteristics | |
Dimensions | (180±6) × (148±12) × (128±6) km [4] |
75±3 km [4] | |
Volume | ~1.8×106 km3 [a] |
Mass | ~(0.71–1.4)×1018 kg [b] |
Mean
density | 0.4–0.8 g/cm3 [5] |
~0.006–0.023 m/s2 [c] | |
~0.032–0.054 km/s [d] | |
synchronous | |
zero | |
Albedo | 0.09 [4] [6] |
Temperature | ~51 K mean (estimate) |
22.0 [6] | |
Despina /dɛˈspaɪnə/, also known as Neptune V, is the third-closest inner moon of Neptune. It is named after Greek mythological character Despoina, a nymph who was a daughter of Poseidon and Demeter.
Despina was discovered in late July 1989 from the images taken by the Voyager 2 probe. It was given the temporary designation S/1989 N 3. [7] The discovery was announced (IAUC 4824) on 2 August 1989, and mentions "10 frames taken over 5 days", implying a discovery date of sometime before July 28. The name was given on 16 September 1991. [8]
Despina's diameter is approximately 150 kilometres (93 mi). [4] Despina is irregularly shaped and shows no sign of any geological modification. It is likely that it is a rubble pile re-accreted from fragments of Neptune's original satellites, which were disrupted by perturbations from Triton soon after that moon's capture into a very eccentric initial orbit. [9]
Despina's orbit lies close to but outside of the orbit of Thalassa and just inside the Le Verrier ring and acts as its shepherd moon. [10] As it is also below Neptune's synchronous orbit radius, it is slowly spiralling inward due to tidal deceleration and may eventually impact Neptune's atmosphere, or break up into a planetary ring upon passing its Roche limit due to tidal stretching.