(48639) 1995 TL8

(48639) 1995 TL8 is a binary trans-Neptunian object from the scattered disc in the outermost regions of the Solar System. It was discovered by Arianna Gleason in 1995 and measures approximately 176 kilometers in diameter. Its 80-kilometer minor-planet moon, provisionally designated S/2002 (48639) 1, was discovered on 9 November 2002.[5]

(48639) 1995 TL8
1995 TL8 and its satellite (unresolved) imaged by the Hubble Space Telescope
Discovery[1][2]
Discovered byA. Gleason (Spacewatch)
Discovery siteKitt Peak National Obs.
Discovery date15 October 1995
Designations
(48639) 1995 TL8
1995 TL8
TNO[1] · Other TNO[3]
detached[4] · distant[2]
Orbital characteristics[1]
Epoch 17 December 2020 (JD 2459200.5)
Uncertainty parameter 2
Observation arc25.26 yr (9,225 days)
Aphelion65.218 AU
Perihelion39.937 AU
52.578 AU
Eccentricity0.2404
381.25 yr (139,251 days)
46.972°
0° 0m 9.36s / day
Inclination0.2499°
260.007°
84.397°
Known satellites1 (D: 80 km)[5]
Physical characteristics
Dimensions176 km[5]
420.27 km (calculated)[6]
495 km (estimated)[7]
0.07 (estimated)[7]
0.10 (assumed)[6]
0.369[5]
RR[8] · C (assumed)[6]
4.667±0.091 (R)[9] · 4.8[1][6] · 5.1[7] · 5.290±0.060[lower-alpha 1]

    Discovery

    1995 TL8 was discovered on 15 October 1995, by American astronomer Arianna Gleason as part of UA's Spacewatch survey at Kitt Peak National Observatory, near Tucson, Arizona.[2]

    It was the first of the bodies presently classified as a scattered-disc object (SDO)[3] to be discovered, preceding the SDO prototype (15874) 1996 TL66 by almost a year.

    Satellite
    Animation of two Hubble images of 1995 TL8's satellite in August 2001

    A companion was discovered by Denise C. Stephens and Keith S. Noll, from observations with the Hubble Space Telescope taken on 9 November 2002, and announced on 5 October 2005. The satellite, designated S/2002 (48639) 1, is relatively large, having a likely mass of about 10% of the primary. Its orbit has not been determined, but it was at a separation of only about 420 kilometres (260 mi) to the primary at the time of discovery, with a possible orbital period of about half a day and an estimated diameter of 161 kilometres (100 mi).[5]

    A relative size and distance comparison of the 1995 TL8 system with the Earth–Moon system. The scale of the Earth–Moon system has been reduced so Earth appears the same size as the 1995 TL8 primary.

    Scattered–extended object

    1995 TL8 is classified as detached object (scattered–extended) by the Deep Ecliptic Survey, since its orbit appears to be beyond significant gravitational interactions with Neptune's current orbit.[4] However, if Neptune migrated outward, there would have been a period when Neptune had a higher eccentricity.

    Simulations made in 2007 show that 1995 TL8 appears to have less than a 1% chance of being in a 3:7 resonance with Neptune, but it does execute circulations near this resonance.[10]

    Left: The near 3:7 resonance pattern of 1995 TL8 with Neptune only moves clockwise. It never halts and reverses course (i.e. librates).
    Right: The orbital period of 1995 TL8 missing the 7:3 (2.333) resonance of Neptune

    Numbering and naming

    This minor planet was numbered by the Minor Planet Center on 20 November 2002.[11] As of 2018, it has not been named.[2]

    See also

    Notes
    1. Lellouch (2013): observations on 11 February 2011 gave an absolute magnitude of 5.290±0.060. Summary figures for (48639) at LCDB not found at ADS (2013A&A...557...60L)

    References
    1. "JPL Small-Body Database Browser: 48639 (1995 TL8)" (2021-01-16 last obs.). Jet Propulsion Laboratory. Retrieved 14 March 2021.
    2. "48639 (1995 TL8)". Minor Planet Center. Retrieved 16 November 2017.
    3. Johnston, Wm. Robert (15 October 2017). "List of Known Trans-Neptunian Objects". Johnston's Archive. Retrieved 16 November 2017.
    4. Marc W. Buie (22 October 2003). "Orbit Fit and Astrometric record for 48639". SwRI (Space Science Department). Retrieved 26 January 2009.
    5. Johnston, Wm. Robert (21 September 2014). "Asteroids with Satellites Database – (48639) 1995 TL8". Johnston's Archive. Retrieved 16 November 2017.
    6. "LCDB Data for (48639)". Asteroid Lightcurve Database (LCDB). Retrieved 16 November 2017.
    7. Michael E. Brown. "How many dwarf planets are there in the outer solar system?". California Institute of Technology. Retrieved 16 November 2017.
    8. Belskaya, Irina N.; Barucci, Maria A.; Fulchignoni, Marcello; Dovgopol, Anatolij N. (April 2015). "Updated taxonomy of trans-neptunian objects and centaurs: Influence of albedo". Icarus. 250: 482–491. Bibcode:2015Icar..250..482B. doi:10.1016/j.icarus.2014.12.004. Retrieved 16 November 2016.
    9. Peixinho, N.; Delsanti, A.; Guilbert-Lepoutre, A.; Gafeira, R.; Lacerda, P. (October 2012). "The bimodal colors of Centaurs and small Kuiper belt objects". Astronomy and Astrophysics. 546: 12. arXiv:1206.3153. Bibcode:2012A&A...546A..86P. doi:10.1051/0004-6361/201219057. S2CID 55876118. Retrieved 16 November 2017.
    10. Emel'Yanenko, V. V.; Kiseleva, E. L. (April 2008). "Resonant motion of trans-Neptunian objects in high-eccentricity orbits". Astronomy Letters. 34 (4): 271–279. Bibcode:2008AstL...34..271E. doi:10.1134/S1063773708040075. S2CID 122634598. Retrieved 16 November 2017.
    11. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 24 February 2018.

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