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Discovery
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|---|---|
| Discovered by | Chadwick A. Trujillo and Jane X. Luu |
| Discovery date | 20 February 1999 |
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Designations
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| MPC designation | (26375) 1999 DE9 |
| Alternate name(s) | none |
| Minor planet category |
TNO 5:2 resonance[1] |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 78.987 AU (11.816233 Tm) |
| Perihelion | 32.324 AU (4.835563 Tm) |
| Semi-major axis | 55.655 AU (8.325898 Tm) |
| Eccentricity | 0.419 |
| Orbital period | 415.21 a (151655.072 d) |
| Average orbital speed | 3.81 km/s |
| Mean anomaly | 17.891° |
| Inclination | 7.620° |
| Longitude of ascending node | 322.993° |
| Argument of perihelion | 159.961° |
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Physical characteristics
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| Dimensions | 461 ±45 km[2] |
| Mass | ≈1×1020? kg[3] |
| Mean density | 2.0? g/cm3 |
| Escape velocity | 0.2670? km/s |
| Sidereal rotation period |
? d |
| Albedo | 0.06-0.08[2] |
| Temperature | ~37 K |
| Spectral type | ? |
| Absolute magnitude (H) | 4.7 |
(26375) 1999 DE9 (also written (26375) 1999 DE9) is a trans-Neptunian object. Light-curve-amplitude analysis shows only small deviations, suggesting 1999 DE9 is a spheroid with small albedo spots and hence a dwarf planet.[4] It was discovered in 1999 by Chad Trujillo and Jane X. Luu.
It is classified as a resonant as its 417-year orbit is in 2:5 resonance with Neptune's orbit.[1] Spectral analysis has shown traces of ice.[5]
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