Misplaced Pages

(55637) 2002 UX₂₅

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° 0 12.96 / day
Inclination	19.484°
Longitude of ascending node	204.68°
Time of perihelion	≈ 5 September 2066 ±3 days
Argument of perihelion	279.00°
Known satellites	1 (ø: 190–260 km)
Physical characteristics
Mean diameter	665±29 km 659±38 km
Mass	(1.25±0.03)×10 kg
Mean density	0.82±0.11 g/cm (assuming equal densities for primary and satellite) 0.80±0.13 g/cm
Equatorial surface gravity	0.075 m/s
Equatorial escape velocity	0.227 km/s
Synodic rotation period	14.382±0.001 h
Geometric albedo	0.107+0.005 −0.008 0.1±0.01
Temperature	≈ 43 K
Spectral type	B–V=1.007±0.043 V−R=0.540±0.030 V−I=1.046±0.034
Apparent magnitude	19.8
Absolute magnitude (H)	3.87±0.02, 4.0

(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/cm. It was discovered on 30 October 2002, by the Spacewatch program; as of August 2024, the object has yet to be named.

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.

Numbering and naming

This minor planet was numbered (55637) by the Minor Planet Center on 16 February 2003 (M.P.C. 47763). As of 2024, it has not been named.

Classification

2002 UX₂₅ has a perihelion of 36.7 AU, which it will next reach in 2065. As of 2020, 2002 UX₂₅ is 40 AU from the Sun.

The Minor Planet Center classifies 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 (q_min) distance of 36.3 AU.

It has been observed 212 times with precovery images dating back to 1991.

Physical characteristics

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 light-curve amplitude is ΔM = 0.21±0.06.

The analysis of combined thermal radiometry of 2002 UX₂₅ from measurements by the Spitzer Space Telescope and Herschel Space Telescope indicates an effective diameter of 692 ± 23 km and albedo of 0.107
_−0.008. Assuming equal albedos for the primary and secondary it leads to the size estimates of ~664 km and ~190 km, respectively. If the albedo of the secondary is half of that of the primary the estimates become ~640 and ~260 km, respectively. Using an improved thermophysical model slightly different sizes were obtained for UX25 and its satellite: 659 km and 230 km, respectively.

2002 UX₂₅ has red featureless spectrum in the visible and near-infrared but has a negative slope in the K-band, which may indicate the presence of the methanol compounds on the surface. It is redder than Varuna, unlike its neutral-colored "twin" 2002 TX300, in spite of similar brightness and orbital elements.

Composition

With a density of 0.82 g/cm, assuming that the primary and satellite have the same density, 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 was believed to be unlikely given the compactability of water ice; this low density thus astonished astronomers. Studies by Grundy et al. suggest that at the low temperatures that prevail beyond Neptune, ice is brittle and can support significant porosity in objects significantly larger than 2002 UX₂₅, particularly if rock is present; the low density could thus be a consequence of this object failing to warm sufficiently during its formation to significantly deform the ice and fill these pore spaces.

Satellite

The discovery of a minor-planet moon 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 8.309±0.0002 days, at a distance of 4770±40 km, yielding a system mass of (1.25±0.03)×10 kg. The eccentricity of the orbit is 0.17±0.03.

This moon is estimated to be 210±30 km in diameter. 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.

References

1. ^ "JPL Small-Body Database Browser: 55637 (2002 UX25)" (2017-01-16 last obs.). Jet Propulsion Laboratory. Retrieved 24 February 2018.
2. ^ "MPEC 2009-C70 :Distant Minor Planets (2009 FEB. 28.0 TT)". Minor Planet Center. 10 February 2009. Retrieved 5 July 2011.
3. ^ Marc W. Buie. "Orbit Fit and Astrometric record for 55637" (2009-10-22 using 60 observations). SwRI (Space Science Department). Retrieved 12 March 2009.
4. JPL Horizons Observer Location: @sun (Perihelion occurs when deldot changes from negative to positive. Uncertainty in time of perihelion is 3-sigma.)
5. ^ Daniel W. E. Green (22 February 2007). "IAUC 8812: Sats OF 2003 AZ_84, (50000), (55637), (90482)". International Astronomical Union Circular. Archived from the original on 19 July 2011. Retrieved 5 July 2011.
6. ^ M.E. Brown (2013). "The density of mid-sized Kuiper belt object 2002 UX25 and the formation of the dwarf planets". The Astrophysical Journal Letters. 778 (2): L34. arXiv:1311.0553. Bibcode:2013ApJ...778L..34B. doi:10.1088/2041-8205/778/2/L34. S2CID 17839077.
7. ^ Fornasier, S.; Lellouch, E.; Müller, P., T.; et al. (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". Astronomy & Astrophysics. 555: A92. arXiv:1305.0449v2. Bibcode:2013A&A...555A..15F. doi:10.1051/0004-6361/201321329. S2CID 119261700.
8. ^ Brown, Michael E.; Butler, Bryan J. (20 June 2017). "The Density of Mid-sized Kuiper Belt Objects from ALMA Thermal Observations". The Astronomical Journal. 154 (1): 19. arXiv:1702.07414. Bibcode:2017AJ....154...19B. doi:10.3847/1538-3881/aa6346.
9. ^ "(55637) 2002 UX25". www.johnstonsarchive.net. Archived from the original on 28 June 2012. Retrieved 21 May 2020.
10. ^ Hainaut, O. R.; Boehnhardt, H.; Protopapa, S. (October 2012). "Colours of minor bodies in the outer solar system. II. A statistical analysis revisited" (PDF). Astronomy & Astrophysics. 546: 20. arXiv:1209.1896. Bibcode:2012A&A...546A.115H. doi:10.1051/0004-6361/201219566. S2CID 54776793.
11. ^ "AstDys (55637) 2002UX25 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 12 December 2020.
12. ^ Cowen, Ron (2013). "Astronomers surprised by large space rock less dense than water". Nature News. doi:10.1038/nature.2013.14135. S2CID 123788849.
13. Marsden, Brian G. (1 November 2002). "MPEC 2002-V08 : 2002 UX25". IAU Minor Planet Center. Harvard-Smithsonian Center for Astrophysics. Retrieved 5 July 2011.
14. John Stansberry; Will Grundy; Mike Brown; Dale Cruikshank; John Spencer; David Trilling; et al. (2008). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope" (PDF). In M. Antonietta Barucci; Hermann Boehnhardt; Dale P. Cruikshank (eds.). The Solar System Beyond Neptune. University of Arizona press. pp. 161–179. arXiv:astro-ph/0702538. Bibcode:2008ssbn.book..161S. ISBN 978-0-8165-2755-7.
15. W.M. Grundy, K.S. Noll, M.W. Buie, S.D. Benecchi, D. Ragozzine & H.G. Roe, 'The Mutual Orbit, Mass, and Density of Transneptunian Binary Gǃkúnǁʼhòmdímà ((229762) 2007 UK₁₂₆)', Icarus (forthcoming, available online 30 March 2019) Archived 7 April 2019 at the Wayback Machine DOI: 10.1016/j.icarus.2018.12.037,
16. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 24 February 2018.
17. "55637 (2002 UX25)". Minor Planet Center. Retrieved 12 December 2020.
18. 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.
19. "The Mutual Orbit, Mass, and Density of Transneptunian Binary" (PDF). 7 April 2019. Archived from the original (PDF) on 7 April 2019. Retrieved 21 May 2020.
20. ^ "Typical densities of snow and ice (kg/m)". Archived from the original on 1 January 2014. Retrieved 21 May 2020.
21. Roatsch Jaumann et al. 2009, p. 765, Tables 24.1–2
22. ^ "2002 UX25 System parameters". Will Grundy. Retrieved 29 August 2023.
23. "(55637) 2002 UX25". Retrieved 28 July 2023.
24. Distant EKO The Kuiper Belt Electronic newsletter, March 2007

External links

• MPEC 2002-V08
• Astronomers surprised by large space rock less dense than water, Ron Cowen, Nature, 13 November 2013
• Scientist finds medium sized Kuiper belt object less dense than water, Bob Yirka, Phys.org, 14 November 2013
• (55637) 2002 UX25 at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• (55637) 2002 UX25 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

v t e Dwarf planets
List of possible dwarf planets Former dwarf planets Phoebe Triton Vesta Pallas Mesoplanet Planemo
Consensus	Ceres Geology Atmosphere Orcus Moon Pluto Geology Atmosphere Moons Haumea Moons Ring Makemake Moon Quaoar Moon Rings Eris Moon Gonggong Moon Sedna
Candidate	Asteroids Hygiea Interamnia Centaurs Chariklo Chiron Pholus 1999 OX3 2013 TC146 2014 NW65 Plutinos Huya Ixion 2001 QF298 2002 VR128 2002 XV93 2003 AZ84 2003 UZ413 2003 VS2 2007 JH43 2017 OF69 Twotinos 2002 WC19 Cubewanos Chaos Salacia Varda Varuna 1998 SN165 2002 AW197 2002 CY248 2002 KX14 2002 MS4 2002 UX25 2003 QW90 2004 GV9 2004 NT33 2004 PF115 2004 TY364 2004 UX10 2005 RN43 2005 UQ513 2010 FX86 Other KBOs 1999 CD158 1999 DE9 2000 YW134 2002 XW93 2010 JO179 2010 VK201 2011 FW62 2011 GM27 2013 FZ27 2014 UM33 2015 AM281 2015 RR245 Scattered disc objects Gǃkúnǁʼhòmdímà Dziewanna 1996 GQ21 1996 TL66 2001 UR163 2002 TC302 2004 XA192 2005 QU182 2005 RM43 2006 QH181 2008 OG19 2010 KZ39 2010 RE64 2010 RF43 2010 JO179 2010 TJ 2010 VZ98 2013 FY27 2014 AN55 2014 EZ51 2014 UZ224 2014 WK509 2015 KH162 2015 RR245 2017 FO161 2018 AG37 2018 VG18 2021 DR15 2021 LL37 Detached objects 2003 FY128 2003 QX113 2004 XR190 2005 TB190 2007 JJ43 2008 ST291 Sednoids 2012 VP113
Category

v t e Natural satellites of the Solar System
Planetary satellites of	Earth Mars Jupiter Saturn Uranus Neptune
Dwarf planet satellites of	Orcus Pluto Haumea Quaoar Makemake Gonggong Eris
Minor-planet moons	Near-Earth Florence Didymos Dimorphos Moshup Squannit 1994 CC 2001 SN263 Main belt Kalliope Linus Euphrosyne Daphne Peneius Eugenia Petit-Prince Sylvia Romulus Remus Minerva Aegis Gorgoneion Camilla Elektra Kleopatra Alexhelios Cleoselene Ida Dactyl Roxane Olympias Pulcova Balam Dinkinesh (Selam) Jupiter trojans Patroclus Menoetius Hektor Skamandrios Eurybates Queta TNOs Lempo Hiisi Paha 2002 UX25 Sila–Nunam Salacia Actaea Varda Ilmarë Gǃkúnǁʼhòmdímà Gǃòʼé ǃHú 2013 FY27
Ranked by size	Ganymede largest: 5268 km / 0.413 Earths Titan Callisto Io Moon Europa Triton Titania Rhea Oberon Iapetus Charon Umbriel Ariel Dione Tethys Dysnomia Enceladus Miranda Vanth Proteus Mimas Ilmarë Nereid Hiʻiaka Actaea Hyperion Phoebe ...
Discovery timeline Inner moons Irregular moons List Planetary-mass moons Naming Subsatellite Regular moons Trojan moons

v t e Solar System
Sun Mercury Venus Earth Mars Ceres Jupiter Saturn Uranus Neptune Orcus Pluto Haumea Quaoar Makemake Gonggong Eris Sedna
Planets, dwarfs, minors Terrestrials Mercury Venus Earth Mars Giants Gas Jupiter Saturn Ice Uranus Neptune Dwarfs Ceres Orcus Pluto Haumea Quaoar Makemake Gonggong Eris Sedna Large Minor Planets Salacia Varuna Ixion List Moons Earth Moon Claimed Mars Phobos Deimos Jupiter Ganymede Callisto Io Europa all 95 Saturn Titan Rhea Iapetus Dione Tethys Enceladus Mimas Hyperion Phoebe all 146 Uranus Titania Oberon Umbriel Ariel Miranda all 28 Neptune Triton Proteus Nereid all 16 Pluto Charon Nix Hydra Kerberos Styx Orcus Vanth Haumea Hiʻiaka Namaka Quaoar Weywot Makemake S/2015 (136472) 1 Gonggong Xiangliu Eris Dysnomia Formation, evolution, contents, and History Star formation Accretion Accretion disk Excretion Capture theory Capture of Triton Circumplanetary disk Circumstellar disc Circumstellar envelope Coatlicue Cosmic dust Debris disk Detached object Disk instability EXCEDE Exozodiacal dust Extraterrestrial materials Curation Sample-return mission Frost/Ice/Snow line Giant-impact hypothesis Grand tack hypothesis Gravitational collapse Hills cloud Hill sphere Interplanetary dust cloud Interplanetary medium/space Interstellar cloud Interstellar medium Interstellar space Kuiper belt Kuiper cliff Late Heavy Bombardment Molecular cloud Nebular hypothesis Nice model Nice 2 model Five-planet Nice model Oort cloud Outer space Planet Disrupted Migration System Planetesimal Formation Merging stars Protoplanetary disk Ring system Roche limit vs. Hill sphere Rubble pile Scattered disc Co-orbital configuration Saturn Moons Kordylewski cloud Rings Earth? Jovian Saturnian (Rhean?) Charikloan Chironean Uranian Neptunian Haumean Quaoarian Hypothetical objects Bagby's moon Chiron Coatlicue Counter-Earth Chrysalis Fifth Giant Hyperion Lilith Mercury's moon Neith Nemesis Nibiru Petit's moon Phaeton Planet Nine Planet Ten Planet V Planet X Subsatellites Synestia Theia Themis Tyche Vulcan Vulcanoids Waltemath's moons Exploration (outline) Colonization Discovery astronomy historical models timeline Space probes timeline list Human spaceflight space stations list programs Mercury Venus Moon mining Mars Ceres Asteroids mining Comets Jupiter Saturn Uranus Neptune Pluto Deep space Small Solar System bodies Comets Damocloids Meteoroids Minor planets names and meanings moons Planetesimal Planetary orbit-crossers Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Trojans Venus Earth Mars Jupiter Trojan camp Greek camp Saturn Uranus Neptune Near-Earth objects NEAs Asteroid belt Asteroids Ceres Vesta Pallas Hygiea active List families PHA exceptional Kirkwood gap Centaurs Trans-Neptunian objects Kuiper belt Cubewanos Plutinos Detached objects Sednoids Scattered disc Hills cloud Oort cloud Lists Comets Possible dwarf planets Gravitationally rounded objects Minor planets Natural satellites Solar System models Solar System objects by size by discovery date Interstellar and circumstellar molecules Related Double planet Lagrange point Moonlet Syzygy Tidal locking
Outline of the Solar System Solar System portal Astronomy portal Earth sciences portal Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe Each arrow (→) may be read as "within" or "part of".

• Minor planet object articles (numbered)
• Classical Kuiper belt objects
• Discoveries by the Spacewatch project
• Possible dwarf planets
• Binary trans-Neptunian objects
• Astronomical objects discovered in 2002
• Solar System