60558 Echeclus

Minor Planet
name=60558 Echeclus
174P/Echeclus
discoverer=Spacewatch
discovery_date=March 3, 2000
designations=mp|2000 EC|98
category=centaur
epoch=December 31, 2006 (JD 2454100.5)
semimajor=1611.498 Gm (10.772 AU)
perihelion=876.276 Gm (5.858 AU)
aphelion=2346.719 Gm (15.687 AU)
eccentricity=0.456
period=12913.822 d (35.36 a)
inclination=4.335°
asc_node=173.319°
arg_peri=162.366°
mean_anomaly=275.435°
speed=8.58 km/s
dimensions=84 kmcite web
date=22 August 2008
title=List of Known Trans-Neptunian Objects
publisher=Johnston's Archive
author=Wm. Robert Johnston
url=http://www.johnstonsarchive.net/astro/tnoslist.html
accessdate=2006-12-26]
mass=3.6e|17? kg
density=2.0? g/cm³
gravity=0.0196? m/s²
escape_velocity=0.0370? km/s
rotation=26.8 hcite web
date=2008-05-07 last obs
title=JPL Small-Body Database Browser: 60558 Echeclus (2000 EC98)
url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=60558
accessdate=2008-09-09]
spectral_class=?
abs_mag=9.35
albedo=0.10?
temperature=~85 K

60558 Echeclus (pronEng|ɪˈkɛkləs "e-kek'-ləs," from _gr. "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 mp|2000 EC|98 (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 [cite web| url=http://www.fg-kometen.de/fgk_hpe.htm| title=Homepage of the VdS-Fachgruppe Kometen| accessdate=2006-04-18] the Committee on Small Bodies Nomenclature (CSBN) gave it the cometary designation 174P/Echeclus.

Echeclus is only the second comet (after Chiron) that has the same name as an asteroid (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: 133P/Elst-Pizarro (7968 Elst-Pizarro), 4015 Wilson-Harrington (107P/Wilson-Harrington), and 118401 LINEAR (176P/LINEAR (LINEAR 52)).

On 30 December, 2005, 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 substances. [cite web| url=http://www.newscientistspace.com/article/dn8976-hybrid-cometasteroid-in-mysterious-breakup.html| title=Hybrid comet-asteroid in mysterious break-up| first=Jeff| last=Hecht| date=11 April 2006| publisher=NewScientist.com news service| accessdate=2006-04-18]

Orbit

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.cite journal
last=Horner |first= J.
coauthors=Evans, N.W.; Bailey, M. E.
title=Simulations of the Population of Centaurs I: The Bulk Statistics
year=2004
url=http://arxiv.org/abs/astro-ph?papernum=0407400
accessdate=2008-09-09 ]

References

ee also

* Centaur (planetoid)
* Minor planet
* Asteroid
* Comet

External links

* [http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Echeclus;orb=1;view=Far Orbital simulation] from JPL (Java) / [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=Echeclus Ephemeris]
* http://www.ast.cam.ac.uk/~jds/coms06.htm