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Discovery
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| Discovered by | Spacewatch |
| Discovery date | March 3, 2000 |
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Designations
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| Alternate name(s) | 2000 EC98 |
| Minor planet category |
centaur |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 2346.719 Gm (15.687 AU) |
| Perihelion | 876.276 Gm (5.858 AU) |
| Semi-major axis | 1611.498 Gm (10.772 AU) |
| Eccentricity | 0.456 |
| Orbital period | 12913.822 d (35.36 a) |
| Average orbital speed | 8.58 km/s |
| Mean anomaly | 275.435° |
| Inclination | 4.335° |
| Longitude of ascending node | 173.319° |
| Argument of perihelion | 162.366° |
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Physical characteristics
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| Dimensions | 84 km[1][2] |
| Mass | 3.6×1017? kg |
| Mean density | 2.0? g/cm3 |
| Equatorial surface gravity | 0.0196? m/s2 |
| Escape velocity | 0.0370? km/s |
| Rotation period | 26.8 h[3] |
| Albedo | 0.04[2] |
| Temperature | ~85 K |
| Spectral type | ? |
| Apparent magnitude | ~18.8[4] |
| Absolute magnitude (H) | 9.35[3] |
60558 Echeclus ( /ɨˈkɛkləs/ e-kek-ləs or /ˈɛkɨkləs/ ek-i-kləs; from Greek: Έχεκλος) is a centaur in the outer Solar System. It was discovered by Spacewatch in 2000 and initially classified as an asteroid with provisional designation 2000 EC98 (also written 2000 EC98). Research in 2001 by Rousselot and Petit at the Besançon observatory in France showed no evidence of cometary activity, but in late December 2005 a cometary coma was detected. In early 2006[5] the Committee on Small Bodies Nomenclature (CSBN) gave it the cometary designation 174P/Echeclus.
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Echeclus is only the second comet (after Chiron) that has an asteroid-like name (rather than the name of its discoverer(s) as with other comets). Chiron is also a centaur; other centaurs are being observed for signs of a cometary coma.
Besides Chiron, three other objects are cross-listed as both comets and asteroids: 7968 Elst-Pizarro (133P/Elst-Pizarro), 4015 Wilson-Harrington (107P/Wilson-Harrington), and 118401 LINEAR (176P/LINEAR).[6]
On 30 December 2005, when 13.1 AU from the Sun, a large chunk of Echeclus was observed to break off, causing a great cloud of dust. Astronomers have speculated this could have been caused by an impact or by an explosive release of volatile substances.[7]
Echeclus appears to have outburst again around June 2011 when it was 8.5 AU from the Sun.[8][9] On 24 June 2011, follow up imaging with the 2 meter Haleakala-Faulkes Telescope South showed the coma of Echeclus to be very close to the sky background limit.[10]
Echeclus comes to perihelion in 2015.[3]
Centaurs have short dynamical lives due to strong interactions with the giant planets. Echeclus is estimated to have an orbital half-life of about 610 kiloannum.[11]
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| Periodic comets (by number) | ||
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| Previous 173P/Mueller |
174P/Echeclus | Next 175P/Hergenrother |
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