View source for 60558 Echeclus

{{Short description|Centaur comet with 34 year orbit}}
{{Use dmy dates|date=April 2025}}
{{Infobox planet
 | minorplanet=yes
 | background=#C7FF8F
 | name=60558 Echeclus<br />174P/Echeclus
 | symbol = [[File:Echeclus symbol (bold).svg|24px]] (astrological)
 | discoverer=[[Spacewatch]]
 | discovered=3 March 2000
 | discovery_site=[[Kitt Peak National Observatory|Kitt Peak Obs.]]
 | mpc_name=(60558) Echeclus
 | alt_names={{mp|2000 EC|98}}, {{mp|2002 GJ|27}}
 | pronounced={{IPAc-en|ˈ|ɛ|k|ᵻ|k|l|ə|s}}
 | named_after=[[Echeclus (mythology)|Ἔχεκλος]] ''Ekheklos''
 | mp_category=[[centaur (minor planet)|Centaur]]
 | orbit_ref=<ref name=jpldata />
 | epoch=13 January 2016 ([[Julian day|JD]] 2457400.5)
 | uncertainty=0
 | semimajor={{Convert|10.680|AU|Tm|abbr=on}}
 | perihelion={{Convert|5.8168|AU|Gm|abbr=on}}
 | aphelion={{Convert|15.544|AU|Tm|abbr=on|lk=on}}
 | eccentricity=0.45537
 | period=34.90 [[Julian year (astronomy)|yr]] (12749 [[Julian year (astronomy)|d]])
 | inclination=4.3445°
 | asc_node=173.335°
 | arg_peri=162.889°
 | mean_anomaly=7.51102[[Degree (angle)|°]]
 | avg_speed=8.58 km/[[second|s]]
 | p_mean_motion=0.0282
 | mean_motion={{Deg2DMS|0.028238|sup=ms}} / day
 | observation_arc=13264 days (36.31 yr)
 | jupiter_moid={{Convert|0.838867|AU|Gm|abbr=on}}
 | tisserand=3.031
 | mean_diameter={{val|60|u=km}}<ref name=johnston>{{cite 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
  |access-date=2006-12-26| archive-url= https://web.archive.org/web/20061216155220/http://johnstonsarchive.net/astro/tnoslist.html| archive-date= 16 December 2006 | url-status= live}}</ref><ref name=spitzer>
{{cite arXiv
  |title=Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope
  |author=John Stansberry
  |author2=Will Grundy
  |author3=Mike Brown
  |author4=Dale Cruikshank
  |author5=John Spencer
  |author6=David Trilling
  |author7=Jean-Luc Margot
  |eprint=astro-ph/0702538
  |date=2007
}}</ref>
 | mass=
 | density=
 | surface_grav=
 | escape_velocity=
 | rotation={{Convert|26.802|h|d|abbr=on|lk=on}}<ref name=jpldata>
{{cite sbdb
  |title=60558 Echeclus (2000 EC98)
  |id=2060558
  |accessdate=12 April 2016
}}</ref>
 | spectral_type= [[Asteroid color indices|B–V]] = {{val|0.841|0.072}}<ref name="Hainaut-2012" /><br />[[Asteroid color indices|V–R]] = {{val|0.502|0.065}}<ref name="Hainaut-2012" />
 | magnitude=~18.8<ref name=AstDys>{{cite web
  |title=AstDys (60558) Echeclus Ephemerides
  |publisher=Department of Mathematics, University of Pisa, Italy
  |url=https://newton.spacedys.com/astdys/index.php?pc=1.1.3.0&n=60558
  |access-date=2010-06-28}}</ref>
 | abs_magnitude=9.6<ref name=jpldata/>
 | albedo=0.04<ref name=spitzer/>
 | single_temperature=~85 [[kelvin|K]]
}}

'''60558 Echeclus''' {{IPAc-en|ˈ|ɛ|k|ᵻ|k|l|ə|s}} is a [[Centaur (minor planet)|centaur]], approximately {{convert|60|km|mi|abbr=off|sp=us|sigfig=2}} in diameter<ref>
https://academic.oup.com/mnras/article/527/2/3624/7332922</ref>
, located in the [[outer Solar System]]. It was discovered by [[Spacewatch]] in 2000 and initially classified as a [[minor planet]] with [[Provisional designation in astronomy|provisional designation]] {{mp|2000 EC|98}} (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 (cometary)|coma]] was detected. In early 2006<ref>{{cite web| url=http://www.fg-kometen.de/fgk_hpe.htm| title=Homepage of the VdS-Fachgruppe Kometen| access-date=2006-04-18| archive-url=https://web.archive.org/web/20060424060815/http://www.fg-kometen.de/fgk_hpe.htm| archive-date=24 April 2006| url-status=dead}}</ref> the Committee on Small Bodies Nomenclature (CSBN) gave it the [[comet]]ary designation '''174P/Echeclus'''. It last came to [[Apsis|perihelion]] in April 2015,<ref name=jpldata/> and was expected to reach about [[apparent magnitude]] 16.7 near [[Opposition (planets)|opposition]] in September 2015.<ref name="MPC-eph"/>

== Name ==
Echeclus <!--({{Lang-el|''Έχεκλος''}})--> is a [[centaur]] in Greek mythology.

60558 Echeclus is only the second comet (after [[2060 Chiron|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), {{mpl|323137|2003 BM|80}} (282P/2003 BM<sub>80</sub>), {{mpl|300163|2006 VW|139}} (288P/2006 VW<sub>139</sub>), {{mpl|457175|2008 GO|98}} (362P/2008 GO<sub>98</sub>),<ref name="dualstatus">[http://www.minorplanetcenter.org/iau/lists/DualStatus.html Dual-Status Objects]</ref> and {{mpl|248370|2005 QN|173}} (433P/2005 QN<sub>173</sub>).<ref>[https://minorplanetcenter.net/iau/ECS/MPCArchive/2021/MPC_20210920.pdf M.P.C. 133823]</ref>

== Activity ==

=== Fragmentation ===
On 30 December 2005, when 13.1 [[Astronomical unit|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 (astrogeology)|volatile substances]].<ref>{{cite web| url=https://www.newscientist.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| access-date=2006-04-18}}</ref>

=== Outbursts ===
Echeclus appears to have outburst again around June 2011 when it was 8.5&nbsp;AU from the Sun.<ref name="Outburst2011"/><ref name="Outburst2011B"/> On 24 June 2011, follow up imaging with the 2 meter [[Faulkes Telescope South|Haleakala-Faulkes Telescope South]] showed the coma of Echeclus to be very close to the sky background limit.<ref name="Outburst2011C"/>

Echeclus outburst again around 7 December 2017 when it was 7.3&nbsp;AU from the Sun, and was 4 magnitudes brighter than expected.<ref>[https://groups.yahoo.com/neo/groups/mpml/conversations/messages/33519 33519 174P/Echeclus outburst (Brian Skiff)]{{dead link|date=December 2023|bot=medic}}{{cbignore|bot=medic}}</ref>

=== 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.<ref name=Wierzchos2017>{{cite journal
  |last=Wierzchos |first= K.
  |author2=Womack, M.
  |author3=Sarid, G.
  |title=Carbon Monoxide in the Distantly Active Centaur (60558) 174P/Echeclus at 6 au
  |date=2017
  |doi=10.3847/1538-3881/aa689c
  |journal=[[The Astronomical Journal]]
  |volume=153
  |issue=5
  |pages=8
  |bibcode = 2017AJ....153..230W |arxiv = 1703.07660 |s2cid= 119093318
 |doi-access= free
 }}</ref>

== Orbit ==
Echeclus came to [[Apsis|perihelion]] in April 2015.<ref name=jpldata/>

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.<ref name=Horner2004a>{{cite journal
  |last=Horner |first= J.
  |author2=Evans, N.W.
  |author3=Bailey, M. E.
  |title=Simulations of the Population of Centaurs I: The Bulk Statistics
  |date=2004
  |doi=10.1111/j.1365-2966.2004.08240.x
  |journal=[[Monthly Notices of the Royal Astronomical Society]]
  |volume=354
  |issue=3
  |pages=798
  |doi-access= free
 |arxiv=astro-ph/0407400
|bibcode = 2004MNRAS.354..798H |s2cid= 16002759
 }}</ref>

== See also ==
* {{Section link|List of centaurs (small Solar System bodies)|60558}}

== References ==
{{reflist
| refs =

<ref name="MPC-eph">{{cite web
  |title=Elements and Ephemeris for 174P/Echeclus
  |publisher=[[Minor Planet Center]]
  |url=https://www.minorplanetcenter.net/cgi-bin/returnprepeph.cgi?d=c&o=0174P
  |access-date=2014-10-31}} (0174P)</ref>

<ref name="Outburst2011">{{cite web
  |date=June 1, 2011
  |title=Outburst of 174P/Echeclus 
  |publisher=Team of observers of Remanzacco Observatory in Italy
  |author=Giovanni Sostero
  |author2=Ernesto Guido
  |name-list-style=amp
  |url=http://remanzacco.blogspot.com/2011/06/outburst-of-174pecheclus.html
  |access-date=2011-06-01}}</ref>

<ref name="Outburst2011B">{{cite web
  |date=June 9, 2011
  |title=Follow-up of 174P/Echeclus bright phase 
  |publisher=Team of observers of Remanzacco Observatory in Italy
  |author=Giovanni Sostero
  |author2=Ernesto Guido
  |name-list-style=amp
  |url=http://remanzacco.blogspot.com/2011/06/follow-up-of-174pecheclus-bright-phase.html
  |access-date=2011-06-09}}</ref>

<ref name="Outburst2011C">{{cite web
  |date=June 24, 2011
  |title=Further follow-up of 174P/Echeclus 
  |publisher=Team of observers of Remanzacco Observatory in Italy
  |author=Nick Howes
  |author2=Giovanni Sostero
  |author3=Ernesto Guido
  |name-list-style=amp
  |url=http://remanzacco.blogspot.com/2011/06/further-follow-up-of-174pecheclus.html
  |access-date=2011-06-24}}</ref>

<ref name="Hainaut-2012">{{Cite journal
  |first1     = O. R. |last1 = Hainaut
  |first2     = H. |last2 = Boehnhardt
  |first3     = S. |last3 = Protopapa
  |date       = October 2012
  |title      = Colours of minor bodies in the outer solar system. II. A statistical analysis revisited
  |url        = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2012A&A...546A.115H
  |journal    = Astronomy and Astrophysics
  |volume     = 546
  |page       = 20
  |bibcode    = 2012A&A...546A.115H
  |doi        = 10.1051/0004-6361/201219566
  |arxiv      = 1209.1896
  |s2cid = 54776793
 |access-date= 26 September 2019}}</ref>

}}

== External links ==
*[https://www.minorplanetcenter.net/cgi-bin/returnprepeph.cgi?d=c&o=0174P Elements and Ephemeris for 174P/Echeclus] (IAU Minor Planet Center)
* [http://www.ast.cam.ac.uk/~jds/coms06.htm BAA Comet Section : Comets discovered in 2006]
* [https://web.archive.org/web/20110928210928/http://astrosurf.com/obsdauban/pages/174P.html 60558 - 0174P/ Echeclus] (2011 June 8)
* [https://www.flickr.com/photos/43846774@N02/5793134979/in/photostream/ Comet 174P Echeclus chased by Asteroid 2716 Tuulikki] (Animation by Joseph Brimacombe on 30 May 2011)
* [http://www.virtualtelescope.eu/2016/09/09/comet-174pecheclus-outburst-evolution-coma-29-aug-06-sept-2016/ Comet 174P/ Echeclus during its 2016 outburst] (Virtual Telescope Project)
* {{AstDys|60558}}
* {{JPL small body|id=60558}}

{{Minor planets navigator| |number=60558| }}
{{Small Solar System bodies}}
{{PeriodicComets Navigator|173P/Mueller|175P/Hergenrother|PageName=174P/Echeclus}}
{{Comets}}
{{Authority control}}

{{DEFAULTSORT:Echeclus}}
[[Category:Centaurs (small Solar System bodies)]]
[[Category:Periodic comets|060558]]
[[Category:Numbered comets|0174]]
[[Category:Discoveries by the Spacewatch project|060558]]
[[Category:Named minor planets]]
[[Category:Astronomical objects discovered in 2000|20000303]]
[[Category:Chiron-type comets]]