(55637) 2002 UX25
(55637) 2002 UX25 (provisional designation 2002 UX25) is a trans-Neptunian object that orbits the Sun in the Kuiper belt beyond Neptune. It briefly garnered scientific attention when it was found to have an unexpectedly low density of about 0.82 g/cm3.
2002 UX25 and satellite, as seen by Hubble | |
| Discovery | |
|---|---|
| Discovered by | Spacewatch (291) |
| Discovery site | Kitt Peak National Obs. |
| Discovery date | 30 October 2002 |
| Designations | |
MPC designation | (55637) 2002 UX25 |
Minor planet category | Cubewano (MPC) Extended (DES) |
| Orbital characteristics | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 2 | |
| Observation arc | 25.26 yr (9,228 days) |
| Earliest precovery date | 12 October 1991 |
| Aphelion | 48.491 AU |
| Perihelion | 36.485 AU |
Semi-major axis | 42.488 AU |
| Eccentricity | 0.1413 |
Orbital period (sidereal) | 276.95 yr (101,157 days) |
Average orbital speed | 4.54 km/s |
Mean anomaly | 295.71° |
Mean motion | 0° 0m 12.96s / day |
| Inclination | 19.484° |
Longitude of ascending node | 204.68° |
| ≈ 5 September 2066 ±3 days | |
| 279.00° | |
| Known satellites | 1 (ø: 190–260 km) |
| Physical characteristics | |
Mean diameter | 665±29 km 659±38 km |
| Mass | (1.25±0.03)×1020 kg |
Mean density | 0.82±0.11 g/cm3 (assuming equal densities for primary and satellite) 0.80±0.13 g/cm3 |
Equatorial surface gravity | 0.075 m/s2 |
Equatorial escape velocity | 0.227 km/s |
Synodic rotation period | 14.382±0.001 h |
| 0.107+0.005 −0.008 0.1±0.01 | |
| Temperature | ≈ 43 K |
| B–V=1.007±0.043 V−R=0.540±0.030 V−I=1.046±0.034 | |
| 19.8 | |
| 3.87±0.02, 4.0 | |
2002 UX25 has an absolute magnitude of about 4.0, and Spitzer Space Telescope results estimate it to be about 681 km in diameter. The low density of this and many other mid sized TNOs implies that they have likely never compressed into fully solid bodies, let alone differentiated or collapsed into hydrostatic equilibrium, and so are highly unlikely to be dwarf planets.
It was discovered on 30 October 2002, by the Spacewatch program.
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