60558 Echeclus

60558 Echeclus /ˈɛkɪkləs/ is a centaur 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]

60558 Echeclus
174P/Echeclus
Discovery
Discovered bySpacewatch
Discovery siteKitt Peak Obs.
Discovery date3 March 2000
Designations
(60558) Echeclus
Pronunciation/ˈɛkɪkləs/
Named after
Ἔχεκλος Ekheklos
2000 EC98, 2002 GJ27
Centaur
Orbital characteristics[1]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 0
Observation arc13264 days (36.31 yr)
Aphelion15.544 AU (2.3253 Tm)
Perihelion5.8168 AU (870.18 Gm)
10.680 AU (1.5977 Tm)
Eccentricity0.45537
34.90 yr (12749 d)
8.58 km/s
7.51102°
0° 1m 41.657s / day
Inclination4.3445°
173.335°
162.889°
Jupiter MOID0.838867 AU (125.4927 Gm)
TJupiter3.031
Proper orbital elements
0.0282 deg / yr
12765.95745 yr
(4662765.957 d)
Physical characteristics
Dimensions84 km[2][3]
26.802 h (1.1168 d)[1]
0.04[3]
Temperature~85 K
B–V = 0.841±0.072[4]
V–R = 0.502±0.065[4]
~18.8[5]
9.6[1]

    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, seven 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), and (457175) 2008 GO98 (362P/2008 GO98).[8]

    Chunk

    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.[9]

    Outbursts

    Echeclus appears to have outburst again around June 2011 when it was 8.5 AU from the Sun.[10][11] 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.[12]

    Echeclus outburst again around 7 December 2017 when it was 7.3 AU from the Sun, and was 4 magnitudes brighter than expected.[13]

    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.[14]

    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.[15]

    See also

    References
    1. "60558 Echeclus (2000 EC98)". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 2060558. Retrieved 12 April 2016.
    2. Wm. Robert Johnston (22 August 2008). "List of Known Trans-Neptunian Objects". Johnston's Archive. Archived from the original on 16 December 2006. Retrieved 2006-12-26.
    3. 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. 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. arXiv:1209.1896. Bibcode:2012A&A...546A.115H. doi:10.1051/0004-6361/201219566. Retrieved 26 September 2019.
    5. "AstDys (60558) Echeclus Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2010-06-28.
    6. "Homepage of the VdS-Fachgruppe Kometen". Archived from the original on 24 April 2006. Retrieved 2006-04-18.
    7. "Elements and Ephemeris for 174P/Echeclus". Minor Planet Center. Retrieved 2014-10-31. (0174P)
    8. Dual-Status Objects
    9. Hecht, Jeff (11 April 2006). "Hybrid comet-asteroid in mysterious break-up". NewScientist.com news service. Retrieved 2006-04-18.
    10. Giovanni Sostero & Ernesto Guido (June 1, 2011). "Outburst of 174P/Echeclus". Team of observers of Remanzacco Observatory in Italy. Retrieved 2011-06-01.
    11. Giovanni Sostero & Ernesto Guido (June 9, 2011). "Follow-up of 174P/Echeclus bright phase". Team of observers of Remanzacco Observatory in Italy. Retrieved 2011-06-09.
    12. Nick Howes; Giovanni Sostero & Ernesto Guido (June 24, 2011). "Further follow-up of 174P/Echeclus". Team of observers of Remanzacco Observatory in Italy. Retrieved 2011-06-24.
    13. 33519 174P/Echeclus outburst (Brian Skiff)
    14. 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. arXiv:1703.07660. Bibcode:2017AJ....153..230W. doi:10.3847/1538-3881/aa689c.
    15. 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. arXiv:astro-ph/0407400. Bibcode:2004MNRAS.354..798H. doi:10.1111/j.1365-2966.2004.08240.x.
    Numbered comets
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