(55637) 2002 UX25

From Infogalactic: the planetary knowledge core
Jump to: navigation, search
(55637) 2002 UX25
20131105 2002 UX25 hst.png
2002 UX25 as seen by Hubble
Discovery[1]
Discovered by Spacewatch (291)
Discovery site Kitt Peak National Obs.
Discovery date 30 October 2002
Designations
MPC designation (55637) 2002 UX25
Cubewano (MPC)[2]
Extended (DES)[3]
Orbital characteristics [6]
Epoch 27 June 2015 (JD 2457200.5)
Uncertainty parameter 3
Observation arc 22.15 yr (8,090 days)
Aphelion 48.803 AU
Perihelion 36.509 AU
42.656 AU
Eccentricity 0.1441
278.60 yr (101,758 days)
4.54 km/s
294.21°
Inclination 19.463°
204.65°
277.89°
Known satellites 1
(ø: ~ 190–260 km)[4][5]
Physical characteristics
Dimensions 665±29 km[7]
Mass (1.25±0.03)×1020 kg[5]
Mean density
 0.82±0.11 g/cm3[5]
Equatorial surface gravity
 0.075 m/s2
Equatorial escape velocity
 0.227 km/s
14.382±0.001 h[8]
0.107+0.005
−0.008 [8]
0.115+0.05
−0.03 [9]
Temperature ≈ 43 K
(pushing red)
B−V=1.12
V−R=0.61[10]
B−V=0.95
V−R=0.56[11][12]

U−B=0.26
B−V=0.98
V−R=0.54±0.03
B−R=1.52
V−I=1.13±0.05
R−J=1.28
V−J=1.82±0.09
J−H=0.4±0.05
V−H=2.22 [8]
19.8 [13]
3.87±0.02 [8]
3.9 [6]

(55637) 2002 UX25 is a possible dwarf planet that orbits the Sun in the Kuiper belt beyond Neptune. Its orbit takes roughly 280 years, and it has one known moon. This moon makes it much easier to calculate mass, and when the size is known, also a density. The low density of about 0.82 g/cm3 has been a surprise to astronomers.[14]

It is a trans-Neptunian object with an absolute magnitude of 3.9,[6] making it highly likely to be a dwarf planet. The Spitzer Space Telescope results estimate it to be about 681 km in diameter.[9] It was discovered on 30 October 2002, by the Spacewatch program.[1] It is a mid-sized cubewano similar in size to 20000 Varuna.

Classification

2002 UX25 (vmag 19.9) as viewed with a 24" telescope

(55637) 2002 UX25 has a perihelion (closest approach to the Sun) of 36.7 AU,[6] which it will next reach in 2065.[6] As of 2010, (55637) 2002 UX25 is 41 AU from the Sun.[13]

The Minor Planet Center (MPC) classifies (55637) 2002 UX25 as a cubewano[2] while the Deep Ecliptic Survey (DES) classifies it as scattered-extended.[3] The DES using a 10 My integration (last observation: 2009-10-22) shows it with a minimum perihelion (qmin) distance of 36.3 AU.[3]

(55637) 2002 UX25 has been observed 60 times with precovery images back to 1991.[6]

Dwarf-planet status

(55637) 2002 UX25 has an estimated diameter of 665±29 km,[7] and most icy objects around 400 km in diameter are believed to be spherical.[15] Michael Brown's website lists it as a highly likely dwarf planet.[16] However, light-curve analysis has questioned whether it is actually a dwarf planet.[17][18]

Physical characteristics

Brightness and color

A variability of the visual brightness was detected which could be fit to a period of 14.38 or 16.78 h (depending on a single-peaked or double peaked curve).[19]

The Spitzer Space Telescope has estimated it to have a size of 681+116
−114 km.[9] It is redder than Varuna, unlike its neutral-colored "twin" 2002 TX300, in spite of similar brightness and orbit elements. The light-curve amplitude is ΔM = 0.21±0.06.[8]

Composition

(55637) 2002 UX25 is one of the largest known solid objects in the Solar System that is less dense than water. Why this should be is not well understood: objects of its size in the Kuiper belt are typically rocky and dense, and to have a similar composition to others of its kind, it would have to be exceptionally porous, which is unlikely given the compactability of water ice.[5] Its density of 0.82 g/cm3 astonished astronomers.[14]

Density comparison
What Density
(g/cm3)		 Notes
Settled snow 0.2–0.3 [20]
Slush/ firn 0.7–0.8 [20]
2002 UX25 0.82 [5]
Glacier ice 0.83–0.92 [20]
Tethys 0.984 [21]
Liquid water 1 [20]

Satellite

The discovery of a satellite of (55637) 2002 UX25 was reported in IAUC 8812 on 22 February 2007.[4] The satellite was detected using the Hubble Space Telescope in August 2005.[4] The satellite was found at 0.16 arcsec from the primary with an apparent magnitude difference of 2.5.[22] It orbits the primary in 8.309±0.0002 days,[8] at a distance of 4770±40 km, yielding a system mass of (1.25±0.03)×1020 kg.[5][8] The eccentricity of the orbit is 0.17±0.03.[8]

This moon is estimated to be 210±30 km in diameter.[7] Assuming the same albedo as the primary, it would have a diameter of 190 km, assuming an albedo of 0.05 (typical of other cold, classical KBOs of similar size) a diameter of 260 km.[5]

References

  1. ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 M.E. Brown, 2013, "The density of mid-sized Kuiper belt object 2002 UX25 and the formation of the dwarf planets"
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ 7.0 7.1 7.2 S. Fornasier, E. Lellouch, T. Müller, P. Santos-Sanz, P. Panuzzo, C. Kiss, T. Lim, M. Mommert, D. Bockelée-Morvan, E. Vilenius, J. Stansberry, G.P. Tozzi, S. Mottola, A. Delsanti, J. Crovisier, R. Duffard, F. Henry, P. Lacerda, A. Barucci, & A. Gicquel (2013). TNOs are Cool: A survey of the trans-Neptunian region. VIII. Combined Herschel PACS and SPIRE observations of 9 bright targets at 70–500 µm.
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 Johnston's Archive for (55637) 2002 UX25
  9. ↑ 9.0 9.1 9.2 Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ TNO Colors
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ 13.0 13.1 Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ 14.0 14.1 Ron Cowen - Nature - Astronomers surprised by large space rock less dense than water Kuiper belt object challenges planet-formation theories. (13 November 2013)
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found. (Which are the dwarfs in the Solar System?)
  18. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  19. ↑ Rousselot, P.; Petit, J.-M.; Poulet, F.; Sergeev, A. Photometric study of Centaur (60558) 2000 EC98 and trans-neptunian object (55637) 2002 UX25 at different phase angles, Icarus, 176, (2005) pp. 478–491.Abstract.
  20. ↑ 20.0 20.1 20.2 20.3 Typical densities of snow and ice (kg/m³)
  21. ↑ Roatsch Jaumann et al. 2009, p. 765, Tables 24.1–2
  22. ↑ Distant EKO The Kuiper Belt Electronic newsletter, March 2007

External links

Retrieved from "https://infogalactic.com/w/index.php?title=(55637)_2002_UX25&oldid=2774264"