60558 Echeclus

Short description: Centaur comet with 34 year orbit

60558 Echeclus
174P/EcheclusDiscovery

Discovered by| Spacewatch
Discovery site| Kitt Peak Obs.
Discovery date| 3 March 2000
Designations

MPC designation

| (60558) Echeclus
Pronunciation| /ˈɛkɪkləs/
Named after| Ἔχεκλος Ekheklos

Alternative designations

| 2000 EC98, 2002 GJ27
Minor planet category| Centaur
Orbital characteristics[1]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 0
Observation arc| 13264 days (36.31 yr)
|{{{apsis}}}|helion}}| 15.544 astronomical unit|AU (2.3253 Tm)
|{{{apsis}}}|helion}}| 5.8168 AU (870.18 Gm)

Semi-major axis

| 10.680 AU (1.5977 Tm)
Eccentricity| 0.45537
Orbital period| 34.90 yr (12749 d)
Average Orbital speed| 8.58 km/s
Mean anomaly| 7.51102°
Mean motion| 0° 1m 41.657s / day
Inclination| 4.3445°
Longitude of ascending node| 173.335°

|{{{apsis}}}|helion}}

| 162.889°
Jupiter MOID| 0.838867 AU (125.4927 Gm)
TJupiter| 3.031
Proper orbital elements
Proper mean motion| 0.0282 deg / yr

Proper Orbital period

| 12765.95745 yr
(4662765.957 d)
Physical characteristics
Mean diameter| 84 km[2][3]
Rotation period| 26.802 h (1.1168 d)[1]
Geometric albedo| 0.04[3]
Physics| ~85 K

Spectral type

| B–V = 0.841±0.072[4]
V–R = 0.502±0.065[4]
Apparent magnitude| ~18.8[5]
Absolute magnitude (H)| 9.6[1]

60558 Echeclus /ˈɛkɪkləs/ is a centaur, approximately 84 kilometers (52 miles) in diameter, located in the outer Solar System. It was discovered by Spacewatch in 2000 and initially classified as a minor planet with provisional designation 2000 EC98 (also written 2000 EC98). Research in 2001 by Rousselot and Petit at the Besançon observatory in France indicated that it was not a comet, but in December 2005 a cometary coma was detected. In early 2006[6] the Committee on Small Bodies Nomenclature (CSBN) gave it the cometary designation 174P/Echeclus. It last came to perihelion in April 2015,[1] and was expected to reach about apparent magnitude 16.7 near opposition in September 2015.[7]

## Contents

* 1 Name
* 2 Activity
* 2.1 Fragmentation
* 2.2 Outbursts
* 2.3 Presence of gas
* 3 Orbit
* 4 See also
* 5 References
* 6 External links

## Name

Echeclus is a centaur in Greek mythology.

60558 Echeclus is only the second comet (after Chiron) that was named as a minor planet, rather than after the name of its discoverer. Chiron is also a centaur; other centaurs are being observed for signs of a cometary coma.

Besides Echeclus, eight other objects are cross-listed as both comets and numbered minor planets: 2060 Chiron (95P/Chiron), 4015 Wilson–Harrington (107P/Wilson–Harrington), 7968 Elst–Pizarro (133P/Elst–Pizarro), 118401 LINEAR (176P/LINEAR), (323137) 2003 BM80 (282P/2003 BM80), (300163) 2006 VW139 (288P/2006 VW139), (457175) 2008 GO98 (362P/2008 GO98),[8] and (248370) 2005 QN173 (433P/2005 QN173).[9]

## Activity

### Fragmentation

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.[10]

### Outbursts

Echeclus appears to have outburst again around June 2011 when it was 8.5 AU from the Sun.[11][12] 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.[13]

Echeclus outburst again around 7 December 2017 when it was 7.3 AU from the Sun, and was 4 magnitudes brighter than expected.[14]

### Presence of gas

In 2016, carbon monoxide was detected in Echeclus in very small amounts, and the derived CO production rate was calculated to be sufficient to account for the observed coma. The calculated CO production rate from Echeclus is substantially lower than what is typically observed for 29P/Schwassmann–Wachmann, another distantly active comet often classified as a centaur.[15]

## Orbit

Echeclus came to perihelion in April 2015.[1]

Centaurs have short dynamical lives due to strong interactions with the giant planets. Echeclus is estimated to have an orbital half-life of about 610,000 years.[16]

## See also

* List of centaurs (small Solar System bodies) § 60558

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 "60558 Echeclus (2000 EC98)". JPL Small-Body Database. Jet Propulsion Laboratory. http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2060558.
2. ↑ Wm. Robert Johnston (22 August 2008). "List of Known Trans-Neptunian Objects". Johnston's Archive. http://www.johnstonsarchive.net/astro/tnoslist.html.
3. ↑ 3.0 3.1 John Stansberry; Will Grundy; Mike Brown; Dale Cruikshank; John Spencer; David Trilling; Jean-Luc Margot (2007). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". arXiv:astro-ph/0702538.
4. ↑ 4.0 4.1 Hainaut, O. R.; Boehnhardt, H.; Protopapa, S. (October 2012). "Colours of minor bodies in the outer solar system. II. A statistical analysis revisited". Astronomy and Astrophysics 546: 20. doi:10.1051/0004-6361/201219566. Bibcode: 2012A&A...546A.115H. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2012A&A...546A.115H. Retrieved 26 September 2019.
5. ↑ "AstDys (60558) Echeclus Ephemerides". Department of Mathematics, University of Pisa, Italy. https://newton.spacedys.com/astdys/index.php?pc=1.1.3.0&n=60558.
6. ↑ "Homepage of the VdS-Fachgruppe Kometen". http://www.fg-kometen.de/fgk_hpe.htm.
7. ↑ "Elements and Ephemeris for 174P/Echeclus". Minor Planet Center. https://www.minorplanetcenter.net/cgi-bin/returnprepeph.cgi?d=c&o=0174P. (0174P)
8. ↑ Dual-Status Objects
9. ↑ M.P.C. 133823
10. ↑ Hecht, Jeff (11 April 2006). "Hybrid comet-asteroid in mysterious break-up". NewScientist.com news service. https://www.newscientist.com/article/dn8976-hybrid-cometasteroid-in-mysterious-breakup.html.
11. ↑ Giovanni Sostero; Ernesto Guido (June 1, 2011). "Outburst of 174P/Echeclus". Team of observers of Remanzacco Observatory in Italy. http://remanzacco.blogspot.com/2011/06/outburst-of-174pecheclus.html.
12. ↑ Giovanni Sostero; Ernesto Guido (June 9, 2011). "Follow-up of 174P/Echeclus bright phase". Team of observers of Remanzacco Observatory in Italy. http://remanzacco.blogspot.com/2011/06/follow-up-of-174pecheclus-bright-phase.html.
13. ↑ Nick Howes; Giovanni Sostero (June 24, 2011). "Further follow-up of 174P/Echeclus". Team of observers of Remanzacco Observatory in Italy. http://remanzacco.blogspot.com/2011/06/further-follow-up-of-174pecheclus.html.
14. ↑ 33519 174P/Echeclus outburst (Brian Skiff)[|permanent dead link|dead link}}]
15. ↑ Wierzchos, K.; Womack, M.; Sarid, G. (2017). "Carbon Monoxide in the Distantly Active Centaur (60558) 174P/Echeclus at 6 au". The Astronomical Journal 153 (5): 8. doi:10.3847/1538-3881/aa689c. Bibcode: 2017AJ....153..230W.
16. ↑ Horner, J.; Evans, N.W.; Bailey, M. E. (2004). "Simulations of the Population of Centaurs I: The Bulk Statistics". Monthly Notices of the Royal Astronomical Society 354 (3): 798. doi:10.1111/j.1365-2966.2004.08240.x. Bibcode: 2004MNRAS.354..798H.

## External links

* Elements and Ephemeris for 174P/Echeclus (IAU Minor Planet Center)
* BAA Comet Section : Comets discovered in 2006
* 60558 - 0174P/ Echeclus (2011 June 8)
* Comet 174P Echeclus chased by Asteroid 2716 Tuulikki (Animation by Joseph Brimacombe on 30 May 2011)
* Comet 174P/ Echeclus during its 2016 outburst (Virtual Telescope Project)
* 60558 Echeclus at AstDyS-2, Asteroids—Dynamic Site
* Ephemeris * Observation prediction * Orbital info * Proper elements * Observational info
* 60558 Echeclus at the JPL Small-Body Database
* Close approach * Discovery * Ephemeris * Orbit diagram * Orbital elements * Physical parameters

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