(127546) 2002 XU93

(127546) 2002 XU93, provisional designation 2002 XU93, is a trans-Neptunian object and centaur on highly inclined and eccentric orbit in the outer region of the Solar System. It measures approximately 170 kilometers (110 mi) in diameter and is one of few objects with such an unusual orbit. It was discovered on 4 December 2002, by American astronomer Marc Buie at the Kitt Peak National Observatory in Arizona, United States.[1]

(127546) 2002 XU93
Hubble Space Telescope image of 2002 XU93 taken in 2009
Discovery [1]
Discovered byM. W. Buie
Discovery siteKitt Peak National Obs.
Discovery date4 December 2002
Designations
(127546) 2002 XU93
2002 XU93
TNO [2] · centaur [3][4][5]
distant [1] · damocloid
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 3
Observation arc8.10 yr (2,957 days)
Aphelion113.59 AU
Perihelion21.003 AU
67.299 AU
Eccentricity0.6879
552.10 yr (201,654 d)
6.1786°
0° 0m 6.48s / day
Inclination77.954°
90.404°
28.135°
TJupiter1.1670
Physical characteristics
Mean diameter
164 km (measured)[4]
170±50 km[6]
180 km (radiometric)[7]
0.038[4]
0.040±0.030[6]
0.04 (radiometric)[7]
BB–BR [4]
B–R = 1.2±0.02[4][8]:23
7.9[7] · 8.0[2]

    Orbit and classification

    2002 XU93 orbits the Sun at a distance of 21–114 AU once every 552 years and 1 month (201,654 days; semi-major axis of 67.3 AU). Its orbit has an eccentricity of 0.69 and an inclination of 78° with respect to the ecliptic.[2] The body's observation arc begins with its official discovery observation at Kitt Peak in December 2002.[1]

    This object belongs to the short-lived population of centaurs. Generically, it is also classified as a trans-Neptunian object as its semi-major axis is larger than Neptune's 30.1 AU. Due to this highly inclined and eccentric orbit, and with a Tisserand's parameter of only 1.167, its cometary-like orbit resembles that of the damocloid and extended-centaur population. It is one of few objects with and inclination above 60° and a perihelion below 15 AU, along with the first discovered 2008 KV42.[9]

    Physical characteristics

    2002 XU93 has a BB–BR taxonomy type.[4] It shows only a moderately red surface with a spectral gradient similar to the known comets, extinct comets, Jupiter trojans, Neptune trojans, irregular satellites and damocloids.[8]

    With a B–R magnitude of 1.2,[8]:23 the difference between the blue and red filter magnitude, it is still redder than the spectrum of the Sun (which is 1.02 mag).[4] It has an absolute magnitude of 8.0.[2]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, 2002 XU93 measures 170 kilometers in diameter and its surface has an low albedo of 0.04.[6] The Johnston's archive gives a mean-diameter of 164 kilometers (102 mi) and albedo of 0.038 from various measurement,[4] while astronomer Michael Brown gives an albedo of 0.04 and a diameter of 180 kilometers (110 mi) from radiometric observations, listing an absolute magnitude of 7.9. Due to its small size, Brown does not consider it to be dwarf-planet candidate, grouping it into the "probably not"-category of his classification scheme (also see list of candidates).[7]

    Rotation period

    As of 2018, no rotational lightcurve of this object has been obtained from photometric observations. The object's rotation period, pole and shape remain unknown.[2][10]

    Numbering and naming

    This minor planet was numbered by the Minor Planet Center on 14 March 2006 (M.P.C. 56238).[11] It has not yet received an official name.[1]

    References
    1. "127546 (2002 XU93)". Minor Planet Center. Retrieved 23 February 2018.
    2. "JPL Small-Body Database Browser: 127546 (2002 XU93)" (2011-01-08 last obs.). Jet Propulsion Laboratory. Retrieved 23 February 2018.
    3. Buie, Marc W. "Orbit Fit and Astrometric record for 127546". SwRI (Space Science Department). Retrieved 23 February 2018.
    4. Johnston, Wm. Robert (30 December 2017). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 23 February 2018.
    5. "List Of Centaurs and Scattered-Disk Objects". Minor Planet Center. Retrieved 23 February 2018.
    6. Bauer, James M.; Grav, Tommy; Blauvelt, Erin; Mainzer, A. K.; Masiero, Joseph R.; Stevenson, Rachel; et al. (August 2013). "Centaurs and Scattered Disk Objects in the Thermal Infrared: Analysis of WISE/NEOWISE Observations". The Astrophysical Journal. 773 (1): 11. arXiv:1306.1862. Bibcode:2013ApJ...773...22B. doi:10.1088/0004-637X/773/1/22.
    7. Brown, Michael E. "How many dwarf planets are there in the outer solar system?". California Institute of Technology. Retrieved 23 February 2018.
    8. Sheppard, Scott S. (April 2010). "The Colors of Extreme Outer Solar System Objects". The Astronomical Journal. 139 (4): 1394–1405. arXiv:1001.3674. Bibcode:2010AJ....139.1394S. doi:10.1088/0004-6256/139/4/1394.
    9. "MPC database query". Minor Planet Center. Retrieved 23 February 2018.
    10. "LCDB Data for (127546) 2002 XU93". Asteroid Lightcurve Database (LCDB). Retrieved 23 February 2018.
    11. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 23 February 2018.

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