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Discovery
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| Discovered by | A. Gleason (Spacewatch) |
| Discovery date | October 15, 1995 and November 9, 2002 (moon) |
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Designations
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| MPC designation | (48639) 1995 TL8 |
| Alternate name(s) | none |
| Minor planet category |
Ext-SDO (DES)[1] |
| Epoch November 30, 2008 (JD 2454800.5) | |
| Aphelion | 65.086 AU 9,736 Gm (Q) |
| Perihelion | 39.980 AU 5,980 Gm (q) |
| Semi-major axis | 52.533 AU 7,858 Gm (a) |
| Eccentricity | 0.23894 |
| Orbital period | 380.77 a (139077 d) |
| Average orbital speed | 4.06 km/s |
| Mean anomaly | 35.705° |
| Inclination | 0.24686° |
| Longitude of ascending node | 260.30° |
| Argument of perihelion | 84.104° |
| Satellites | 1 |
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Physical characteristics
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| Dimensions | ~350 (primary) and ~160 km (secondary) |
| Albedo | 0.09 (assumed) |
| Temperature | ~38 K |
| Absolute magnitude (H) | 5.28 and 6.98 |
(48639) 1995 TL8 (also written (48639) 1995 TL8) is a detached (extended–scattered disc) trans-Neptunian object possessing a relatively large satellite.
The assumed diameter of 352 km is derived from an albedo guess of 0.09, being typical for trans-Neptunian objects.[3]
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Discovered in 1995 by Arianna E. Gleason as part of the Spacewatch project, it was the first of the bodies presently classified as a scattered-disc object (SDO) to be discovered, preceding the SDO prototype (15874) 1996 TL66 by almost a year.
A companion was discovered by Denise C. Stephens and Keith S. Noll from observations with the Hubble Space Telescope taken on November 9, 2002, and announced on October 5, 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 km to the primary at the time of discovery, with a possible orbital period of about half a day and an estimated diameter of 161 km.[4]
(48639) 1995 TL8 is classified as scattered–extended by the Deep Ecliptic Survey (DES) since its orbit appears to be beyond significant gravitational interactions with Neptune's current orbit.[1] Though if Neptune migrated outward, there would have been a period when Neptune had a higher eccentricity.
Simulations by Emel’yanenko and Kiseleva in 2007 show that (48639) 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.[5]
It has been observed 48 times and has an orbit quality code of 4 (0 being best; 9 being worst).[2]
To see a proper 3:7 resonance with Neptune, see: (131696) 2001 XT254.
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