(55637) 2002 UX25

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(55637) 2002 UX25
20131105 2002 UX25 hst.png
2002 UX25 and satellite, as seen by Hubble
Discovery [1]
Discovered by Spacewatch (291)
Discovery site Kitt Peak National Obs.
Discovery date30 October 2002
Designations
(55637) 2002 UX25
Cubewano (MPC) [2]
Extended (DES) [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 2
Observation arc 25.26 yr (9,228 days)
Earliest precovery date12 October 1991
Aphelion 48.491 AU
Perihelion 36.485 AU
42.488 AU
Eccentricity 0.1413
276.95 yr (101,157 days)
Average orbital speed
4.54 km/s
295.71°
0° 0m 12.96s / day
Inclination 19.484°
204.68°
≈ 5 September 2066 [4]
±3 days
279.00°
Known satellites 1
(ø: 190–260 km) [5] [6]
Physical characteristics
665±29 km [7]
659±38 km [8]
Mass (1.25±0.03)×1020 kg [6]
Mean density
0.82±0.11 g/cm3
(assuming equal densities
for primary and satellite) [6]
0.80±0.13 g/cm3 [8]
Equatorial surface gravity
0.075 m/s2
Equatorial escape velocity
0.227 km/s
14.382±0.001 h [9]
0.107+0.005
−0.008 [7]
0.1±0.01 [8]
Temperature ≈ 43 K
B–V=1.007±0.043 [10]
V−R=0.540±0.030 [10]
V−I=1.046±0.034 [10]
19.8 [11]
3.87±0.02, [9] 4.0 [1]

    (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. [12] It was discovered on 30 October 2002, by the Spacewatch program; [13] as of August 2024, the object has yet to be named.

    Contents

    2002 UX25 has an absolute magnitude of about 4.0, [1] and Spitzer Space Telescope results estimate it to be about 681 km in diameter. [14] The low density of this and many other mid-sized TNOs implies that they have never compressed into fully solid bodies, let alone differentiated or collapsed into hydrostatic equilibrium, and so are highly unlikely to be dwarf planets. [15]

    Numbering and naming

    This minor planet was numbered (55637) by the Minor Planet Center on 16 February 2003 ( M.P.C. 47763). [16] As of 2024, it has not been named. [17]

    Classification

    2002 UX25 (vmag 19.9) as viewed with a 24" telescope UX25-LB1-2009Nov19-06UT.jpg
    2002 UX25 (vmag 19.9) as viewed with a 24" telescope

    2002 UX25 has a perihelion of 36.7  AU, [1] which it will next reach in 2065. [1] As of 2020, 2002 UX25 is 40 AU from the Sun. [11]

    The Minor Planet Center classifies 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]

    It has been observed 212 times with precovery images dating back to 1991. [1]

    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). [18] The light-curve amplitude is ΔM = 0.21±0.06. [9]

    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+0.005
    −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. [6] Using an improved thermophysical model slightly different sizes were obtained for UX25 and its satellite: 659 km and 230 km, respectively. [8]

    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. [7] 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/cm3, 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. [12] 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; [6] this low density thus astonished astronomers. [12] 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. [19]

    Density comparison
    MaterialDensity
    (g/cm3)    		Notes
    Settled snow0.2–0.3 [20]
    Slush/firn 0.7–0.8 [20]
    2002 UX250.82 [6]
    Glacier ice0.83–0.92 [20]
    Tethys 0.984 [21]
    Liquid water1 [20]

    Satellite

    A simulated circular orbit of 210-km-diameter moon at a distance of 4770 km 2002 UX25 moon-orbit.png
    A simulated circular orbit of 210-km-diameter moon at a distance of 4770 km
    Discovery
    Discovered by Brown et al.
    Discovery date2007
    Orbital characteristics
    4750±40 km [22]
    Eccentricity 0.18±0.02 [22]
    8.3095 d (prograde) [22]
    Inclination 63.1° [22]
    Satellite of 2002 UX25
    Physical characteristics
    105±15 km [23]

      The discovery of a minor-planet moon was reported in IAUC 8812 on 22 February 2007. [5] The satellite was detected using the Hubble Space Telescope in August 2005. [5] The satellite was found at 0.16 arcsec from the primary with an apparent magnitude difference of 2.5. [24] It orbits the primary in 8.309±0.0002 days, [9] at a distance of 4770±40 km, yielding a system mass of (1.25±0.03)×1020 kg. [6] [9] The eccentricity of the orbit is 0.17±0.03. [9]

      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. [6]

      Related Research Articles

      A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU).

      <span class="mw-page-title-main">28978 Ixion</span> Plutino

      28978 Ixion (, provisional designation 2001 KX76) is a large trans-Neptunian object and a possible dwarf planet. It is located in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. Ixion is classified as a plutino, a dynamical class of objects in a 2:3 orbital resonance with Neptune. It was discovered in May 2001 by astronomers of the Deep Ecliptic Survey at the Cerro Tololo Inter-American Observatory, and was announced in July 2001. The object is named after the Greek mythological figure Ixion, who was a king of the Lapiths.

      <span class="mw-page-title-main">20000 Varuna</span> Kuiper belt object

      20000 Varuna (provisional designation 2000 WR106) is a large trans-Neptunian object in the Kuiper belt. It was discovered in November 2000 by American astronomer Robert McMillan during a Spacewatch survey at the Kitt Peak National Observatory. It is named after the Hindu deity Varuna, one of the oldest deities mentioned in the Vedic texts.

      <span class="mw-page-title-main">Orcus (dwarf planet)</span> Trans-Neptunian dwarf planet

      Orcus is a dwarf planet located in the Kuiper belt, with one large moon, Vanth. It has an estimated diameter of 870 to 960 km, comparable to the Inner Solar System dwarf planet Ceres. The surface of Orcus is relatively bright with albedo reaching 23 percent, neutral in color, and rich in water ice. The ice is predominantly in crystalline form, which may be related to past cryovolcanic activity. Other compounds like methane or ammonia may also be present on its surface. Orcus was discovered by American astronomers Michael Brown, Chad Trujillo, and David Rabinowitz on 17 February 2004.

      (15874) 1996 TL66 (provisional designation 1996 TL66) is a trans-Neptunian object of the scattered disc orbiting in the outermost region of the Solar System.

      <span class="nowrap">(55565) 2002 AW<sub>197</sub></span> Classical Kuiper belt object

      (55565) 2002 AW197 (provisional designation 2002 AW197) is a classical, non-resonant trans-Neptunian object from the Kuiper belt in the outermost region of the Solar System, also known as a cubewano. It is the tenth-intrinsically-brightest known trans-Neptunian objct, and with a likely diameter of at least 600 kilometers (400 miles), it is approximately tied with 2002 MS4 and 2013 FY27 (to within measurement uncertainties) as the largest unnamed object in the Solar System. It was discovered at Palomar Observatory in 2002.

      <span class="nowrap">(84522) 2002 TC<sub>302</sub></span> Large trans-Neptunian object

      (84522) 2002 TC302 (provisional designation 2002 TC302) is a mid-sized trans-Neptunian object located in the outermost region of the Solar System. It was discovered on 9 October 2002, by American astronomers Mike Brown, Chad Trujillo and David Rabinowitz at the Palomar Observatory in California. The resonant trans-Neptunian object stays in a 2:5 resonance with Neptune. It has a reddish color, a rotation period of 56.1 hours and measures at least 500 kilometers (310 miles) in diameter.

      <span class="mw-page-title-main">7066 Nessus</span> Very red centaur on an eccentric orbit beyond Saturn in the outer Solar System

      7066 Nessus is a very red centaur on an eccentric orbit, located beyond Saturn in the outer Solar System. It was discovered on 26 April 1993, by astronomers of the Spacewatch program at the Kitt Peak National Observatory in Tucson, Arizona. The dark and reddish minor planet is likely elongated and measures approximately 60 kilometers in diameter. It was named after Nessus from Greek mythology.

      <span class="mw-page-title-main">10370 Hylonome</span>

      10370 Hylonome (; prov. designation: 1995 DW2) is a minor planet orbiting in the outer Solar System. The dark and icy body belongs to the class of centaurs and measures approximately 72 kilometers (45 miles) in diameter. It was discovered on 27 February 1995, by English astronomer David C. Jewitt and Vietnamese American astronomer Jane Luu at the U.S. Mauna Kea Observatory in Hawaii, and later named after the mythological creature Hylonome.

      <span class="nowrap">(55636) 2002 TX<sub>300</sub></span> Kuiper Belt object

      (55636) 2002 TX300 is a bright Kuiper belt object in the outer Solar System estimated to be about 286 kilometres (178 mi) in diameter. It is a large member of the Haumea family that was discovered on 15 October 2002 by the Near-Earth Asteroid Tracking (NEAT) program.

      <span class="nowrap">(307261) 2002 MS<sub>4</sub></span> Classical Kuiper belt object

      (307261) 2002 MS4 (provisional designation 2002 MS4) is a large trans-Neptunian object in the Kuiper belt, which is a region of icy planetesimals beyond Neptune. It was discovered on 18 June 2002 by Chad Trujillo and Michael Brown during their search for bright, Pluto-sized Kuiper belt objects at Palomar Observatory. To within measurement uncertainties, 2002 MS4, 2002 AW197, and 2013 FY27 have a diameter close to 800 km (500 mi), which makes them the largest unnamed objects in the Solar System. 2002 MS4 is large enough that some astronomers conclude that it might be a dwarf planet.

      <span class="nowrap">(208996) 2003 AZ<sub>84</sub></span> Plutino

      (208996) 2003 AZ84 (provisional designation 2003 AZ84) is a trans-Neptunian object with a possible moon located in the outer regions of the Solar System. It is approximately 940 kilometers across its longest axis, as it has an elongated shape. It belongs to the plutinos – a group of minor planets named after its largest member Pluto – as it orbits in a 2:3 resonance with Neptune in the Kuiper belt. It is the third-largest known plutino, after Pluto and Orcus. It was discovered on 13 January 2003, by American astronomers Chad Trujillo and Michael Brown during the NEAT survey using the Samuel Oschin telescope at Palomar Observatory.

      <span class="mw-page-title-main">174567 Varda</span> Trans-Neptunian object

      174567 Varda (provisional designation 2003 MW12) is a binary trans-Neptunian planetoid of the resonant hot classical population of the Kuiper belt, located in the outermost region of the Solar System. Its moon, Ilmarë, was discovered in 2009.

      <span class="nowrap">(84922) 2003 VS<sub>2</sub></span> Trans-Neptunian object

      (84922) 2003 VS2 is a trans-Neptunian object discovered by the Near Earth Asteroid Tracking program on 14 November 2003. Like Pluto, it is in a 2:3 orbital resonance with Neptune and is thus a plutino. Analysis of light-curve suggests that it is not a dwarf planet.

      (24835) 1995 SM55 (provisional designation 1995 SM55) is a trans-Neptunian object and member of the Haumea family that resides in the Kuiper belt, located in the outermost region of the Solar System. It was discovered on 19 September 1995, by American astronomer Nichole Danzl of the Spacewatch program at Kitt Peak National Observatory near Tucson, Arizona, in the United States. It measures approximately 200 kilometers in diameter and was the second-brightest known object in the Kuiper belt, after Pluto, until 1996 TO66 was discovered.

      <span class="nowrap">(26308) 1998 SM<sub>165</sub></span>

      (26308) 1998 SM165 is a resonant trans-Neptunian object and binary system from the Kuiper belt in the outermost regions of the Solar System. It was discovered on 16 September 1998, by American astronomer Nichole Danzl at the Kitt Peak National Observatory in Arizona. It is classified as a twotino and measures approximately 280 kilometers in diameter. Its minor-planet moon was discovered in 2001.

      (35671) 1998 SN165 (provisional designation 1998 SN165) is a trans-Neptunian object from the Kuiper belt located in the outermost region of the Solar System. It was discovered on 23 September 1998, by American astronomer Arianna Gleason at the Kitt Peak National Observatory near Tucson, Arizona. The cold classical Kuiper belt object is a dwarf planet candidate, as it measures approximately 400 kilometers (250 miles) in diameter. It has a grey-blue color (BB) and a rotation period of 8.8 hours. As of 2021, it has not been named.

      <span class="nowrap">(82075) 2000 YW<sub>134</sub></span>

      (82075) 2000 YW134 (provisional designation 2000 YW134) is a resonant trans-Neptunian object and binary system, located in the outermost region of the Solar System. It was discovered on 26 December 2000, by astronomers with the Spacewatch survey at Kitt Peak Observatory near Tucson, Arizona. The reddish object stays in a rare 3:8 resonance with Neptune. A smaller companion was discovered by the Hubble Space Telescope in October 2002. As of 2021, neither the primary body nor its satellite have been named.

      <span class="nowrap">(524366) 2001 XR<sub>254</sub></span>

      (524366) 2001 XR254, provisional designation 2001 XR254, is a trans-Neptunian object and binary system from the classical Kuiper belt, located in the outermost region of the Solar System. The cubewano belongs to the cold population and measures approximately 171 kilometers (110 miles). It was first observed on 10 December 2001, by astronomers at the Mauna Kea Observatory, Hawaii. Its 140-kilometer sized companion was discovered by the Hubble Space Telescope in June 2006.

      <span class="nowrap">(523794) 2015 RR<sub>245</sub></span>

      (523794) 2015 RR245, provisional designation 2015 RR245, is a large trans-Neptunian object of the Kuiper belt in the outermost regions of the Solar System. It was discovered on 9 September 2015, by the Outer Solar System Origins Survey at Mauna Kea Observatories on the Big island of Hawaii, in the United States. The object is in a rare 2:9 resonance with Neptune and measures approximately 600 kilometers in diameter. 2015 RR245 was suspected to have a satellite according to a study announced by Noyelles et al. in a European Planetary Science Congress meeting in 2019.

      References

      1. 1 2 3 4 5 6 7 "JPL Small-Body Database Browser: 55637 (2002 UX25)" (2017-01-16 last obs.). Jet Propulsion Laboratory . Retrieved 24 February 2018.
      2. 1 2 "MPEC 2009-C70 :Distant Minor Planets (2009 FEB. 28.0 TT)". Minor Planet Center. 10 February 2009. Retrieved 5 July 2011.
      3. 1 2 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. 1 2 3 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. 1 2 3 4 5 6 7 8 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. 1 2 3 4 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. 1 2 3 4 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. 1 2 3 4 5 6 "(55637) 2002 UX25". www.johnstonsarchive.net. Archived from the original on 28 June 2012. Retrieved 21 May 2020.
      10. 1 2 3 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. 1 2 "AstDys (55637) 2002UX25 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 12 December 2020.
      12. 1 2 3 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. 1 2 3 4 "Typical densities of snow and ice (kg/m3)". 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. 1 2 3 4 "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
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