(55637) 2002 UX25
2002 UX25 as seen by Hubble
|Discovered by||Spacewatch (291)|
|Discovery site||Kitt Peak National Obs.|
|Discovery date||30 October 2002|
|MPC designation||(55637) 2002 UX25|
|Orbital characteristics |
|Epoch 27 June 2015 (JD 2457200.5)|
|Uncertainty parameter 3|
|Observation arc||22.15 yr (8,090 days)|
|278.60 yr (101,758 days)|
Average orbital speed
(ø: ~ 190–260 km)
(assuming equal densities
for primary and satellite)
Equatorial surface gravity
Equatorial escape velocity
Sidereal rotation period
|Temperature||≈ 43 K|
(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 surprised astronomers.
It is a trans-Neptunian object with an absolute magnitude of 4.0, making it highly likely to be a dwarf planet. The Spitzer Space Telescope results estimate it to be about 681 km in diameter. It was discovered on 30 October 2002, by the Spacewatch program. It is a mid-sized cubewano similar in size to 20000 Varuna.
The Minor Planet Center (MPC) classifies (55637) 2002 UX25 as a cubewano while the Deep Ecliptic Survey (DES) classifies it as scattered-extended. The DES using a 10 My integration (last observation: 2009-10-22) shows it with a minimum perihelion (qmin) distance of 36.3 AU.
(55637) 2002 UX25 has an estimated diameter of ±29 km, 665 and most icy objects around 400 km in diameter are thought to be spherical. Michael Brown's website lists it as highly likely a dwarf planet. However, light-curve analysis has questioned whether it is actually a dwarf planet.
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).
The Spitzer Space Telescope has estimated it to have a size of +116
−114 km. 681 It is redder than Varuna, unlike its neutral-colored "twin" 2002 TX300, in spite of similar brightness and orbital elements. The light-curve amplitude is ΔM = ±0.06. 0.21
With a density of 0.82 g/cm3, assuming that the primary and satellite have the same density, (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, because objects of its size in the Kuiper belt often contain a fair amount of rock and are hence pretty dense. To have a similar composition to others large KBOs, it would have to be exceptionally porous, which is unlikely given the compactability of water ice. Hence, its density astonished astronomers.
The discovery of a satellite of (55637) 2002 UX25 was reported in IAUC 8812 on 22 February 2007. The satellite was detected using the Hubble Space Telescope in August 2005. The satellite was found at 0.16 arcsec from the primary with an apparent magnitude difference of 2.5. It orbits the primary in ±0.0002 days, 8.309 at a distance of ±40 km, yielding a system mass of 4770±0.03)×1020 kg. (1.25 The eccentricity of the orbit is ±0.03. 0.17
This moon is estimated to be ±30 km in diameter. 210 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.
- Marsden, Brian G. (2002-11-01). "MPEC 2002-V08 : 2002 UX25". IAU Minor Planet Center. Harvard-Smithsonian Center for Astrophysics. Retrieved 2011-07-05.
- "MPEC 2009-C70 :Distant Minor Planets (2009 FEB. 28.0 TT)". Minor Planet Center. 2009-02-10. Retrieved 2011-07-05.
- Marc W. Buie. "Orbit Fit and Astrometric record for 55637" (2009-10-22 using 60 observations). SwRI (Space Science Department). Retrieved 2009-03-12.
- Daniel W. E. Green (2007-02-22). "IAUC 8812: Sats OF 2003 AZ_84, (50000), (55637), (90482)". International Astronomical Union Circular. Archived from the original on 19 July 2011. Retrieved 2011-07-05.
- M.E. Brown, 2013, "The density of mid-sized Kuiper belt object 2002 UX25 and the formation of the dwarf planets"
- "JPL Small-Body Database Browser: 55637 (2002 UX25)" (2013-12-05 last obs.). Jet Propulsion Laboratory. Retrieved October 2015.
- 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.
- Johnston's Archive for (55637) 2002 UX25
- John Stansberry; Will Grundy; Mike Brown; Dale Cruikshank; John Spencer; David Trilling; et al. (2007). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". arXiv:astro-ph/0702538 [astro-ph].
- TNO Colors
- Tegler, Stephen C. (2007-02-01). "Kuiper Belt Object Magnitudes and Surface Colors". Retrieved 2009-12-30.
- Doressoundiram (2004). "The Meudon Multicolor Survey (2MS) of Centraurs and Trans-Neptunian objects" (PDF). Retrieved 2006-11-06.
- "AstDys (55637) 2002UX25 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2009-11-19.
- Ron Cowen - Nature - Astronomers surprised by large space rock less dense than water Kuiper belt object challenges planet-formation theories. (13 November 2013)
- Mike Brown. "The Dwarf Planets". Archived from the original on 29 January 2008. Retrieved 2008-01-20.
- Michael E. Brown. "How many dwarf planets are there in the outer solar system? (updates daily)". California Institute of Technology. Retrieved 2011-08-25.
- Gonzalo Tancredi & Sofía Favre (13 October 2008). "Dwarf Planet & Plutoid Headquarters". Portal Uruguayo de Astronomía. Retrieved 2010-09-22. (Which are the dwarfs in the Solar System?)
- Tancredi, Gonzalo (2009). "Physical and dynamical characteristics of icy "dwarf planets" (plutoids)". Proceedings of the International Astronomical Union Symposium S263 5: 173–185. Bibcode:2010IAUS..263..173T. doi:10.1017/S1743921310001717.
- 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.
- Typical densities of snow and ice (kg/m³)
- Roatsch Jaumann et al. 2009, p. 765, Tables 24.1–2
- Distant EKO The Kuiper Belt Electronic newsletter, March 2007
- Orbital simulation from JPL (Java) / Ephemeris
- MPEC 2002-V08
- Strange Object Boosts Kuiper Belt Mystery (Discovery 13 Nov 2013)