(120216) 2004 EW95

(120216) 2004 EW95, provisionally known as 2004 EW95, is a resonant trans-Neptunian object in the Kuiper belt located in the outermost regions of the Solar System. It measures approximately 291 kilometers in diameter.[7] It has more carbon than typical of KBOs, and the first to be confirmed as having this composition in this region of space.[8] It is thought that it had originated closer to the Sun, maybe even the main asteroid belt.[8]

(120216) 2004 EW95
Hubble Space Telescope image of 2004 EW95 taken in 2010
Discovery[1]
Discovered byKitt Peak Obs.
Discovery date14 March 2004
Designations
(120216) 2004 EW95
Orbital characteristics[1]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 2
Observation arc4847 days (13.27 yr)
Aphelion52.590 AU (7.8674 Tm)
Perihelion26.975 AU (4.0354 Tm)
39.783 AU (5.9515 Tm)
Eccentricity0.32193
250.93 yr (91652 d)
359.95°
0° 0m 14.219s / day (n)
Inclination29.234°
25.704°
204.67°
Earth MOID25.99 AU (3.888 Tm)
Jupiter MOID21.69 AU (3.245 Tm)
Uranus MOID9 AU (1.3 Tm)[4]
Physical characteristics
Dimensions291 km[5]
0.04 (dark)[5]
~21.0[6]
6.3[1]

    Orbit
    2004 EW95 is currently well inside the orbit of Neptune.

    Like Pluto, 2004 EW95 is classified as a plutino. It stays in a 2:3 resonance with Neptune.[2][3] For every 2 orbits that a plutino makes, Neptune orbits 3 times.

    2004 EW95 is currently 27.0 AU from the Sun,[6] and came to perihelion (q=26.98 AU) in April 2018.[1] This means that this object is currently inside the orbit of the planet Neptune. Like Pluto, this plutino spends part of its orbit closer to the Sun than Neptune is even though their orbits are controlled by Neptune. (Plutinos Huya and (15875) 1996 TP66 are even currently inside the orbit of Neptune.) Simulations by the Deep Ecliptic Survey (DES) show that over the next 10 million years 2004 EW95 can acquire a perihelion distance (qmin) as small as 24.6 AU.[3]

    It comes within 9 AU (1.3 billion km) of Uranus and stays more than 21 AU from Neptune over a 14,000 year period.[4] 2004 EW95 has been observed 158 times with an observation arc of 13 years and has an orbit quality of 2.[1]

    Physical characteristics
    Artist's impression of plutino and possible former C-type asteroid 2004 EW95[9]

    2004 EW95 has a dark albedo of 0.04, giving it a diameter of about 291 km.[5] Its reflectance spectrum bears striking resemblance to those of some hydrated C-type asteroids, indicating that this object possibly formed in the same environment as the C-type asteroids found today in the outer asteroid belt.[10]

    Unlike the majority of small objects in the Kuiper belt observed so far, the visible spectrum of 2004 EW95 has two features, each respectively associated with ferric oxides and phyllosilicates.[10] The presence of a phyllosilicate feature in the spectrum of a minor planet indicates that the rocky component of its composition has been altered by the presence of liquid water at some point since its formation.[11] For this to have occurred on 2004 EW95 in its current orbit and at temperatures of ~35K,[12] significant quantities of thermal energy would have been required. While this energy could have been delivered by a very large chance collision,[13] the strong overall similarity between the modern C-type asteroids in the outer asteroid belt and 2004 EW95 suggests that these objects formed in the same region of the early Sun's protoplanetary disk, much closer to the Sun and at higher temperatures.

    The Grand tack hypothesis[14] predicts that the primitive C-type asteroids were dispersed from their formation location by the migrations of Jupiter and Saturn and many were injected into the outer asteroid belt where we find them today. By the same mechanism (and others that result from planetary formation),[15] simulations show that C-types can also be thrown outward to the trans-Neptunian region, where later they may become captured into the mean-motion resonances of Neptune.[14][15]

    See also

    References
    1. "JPL Small-Body Database Browser: 120216 (2004 EW95)" (last observation: 2015-06-19). Retrieved 7 April 2016.
    2. "MPEC 2009-E53 :Distant Minor Planets (2009 MAR. 30.0 TT)". Minor Planet Center. 11 March 2009. Retrieved 24 March 2009.
    3. Marc W. Buie. "Orbit Fit and Astrometric record for 120216" (last observation: 2009-05-26 using 44 observations). SwRI (Space Science Department). Archived from the original on 1 February 2018. Retrieved 18 September 2009.
    4. "MPEC 2004-H77 : 2004 EW95". Minor Planet Center. 26 April 2004. Retrieved 24 March 2009.
    5. Wm. Robert Johnston (22 August 2008). "List of Known Trans-Neptunian Objects". Johnston's Archive. Archived from the original on 15 April 2009. Retrieved 24 March 2009.
    6. "AstDys (120216) 2004EW95 Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 27 February 2012. Retrieved 24 March 2009.
    7. St. Fleur, Nicholas (10 May 2018). "This Asteroid Shouldn't Be Where Astronomers Found It". The New York Times. Retrieved 11 May 2018.
    8. "Exiled asteroid discovered in outer reaches of solar system: ESO telescopes find first confirmed carbon-rich asteroid in Kuiper Belt". ScienceDaily. Retrieved 1 November 2018.
    9. "Exiled Asteroid Discovered in Outer Reaches of Solar System – ESO telescopes find first confirmed carbon-rich asteroid in Kuiper Belt". www.eso.org. Retrieved 12 May 2018.
    10. Seccull, Tom; Fraser, Wesley C.; Puzia, Thomas H.; Brown, Michael E.; Schönebeck, Frederik (2018). "2004 EW95: A phyllosilicate bearing carbonaceous asteroid in the Kuiper Belt". The Astrophysical Journal. 855 (2): L26. arXiv:1801.10163. Bibcode:2018ApJ...855L..26S. doi:10.3847/2041-8213/aab3dc. S2CID 51688469.
    11. Fornasier, S.; Lantz, C.; Barucci, M. A.; Lazzarin, M. (2014). "Aqueous alteration on main belt primitive asteroids: Results from visible spectroscopy". Icarus. 233: 163–178. arXiv:1402.0175. Bibcode:2014Icar..233..163F. doi:10.1016/j.icarus.2014.01.040. S2CID 119234996.
    12. Mommert, M.; Harris, A. W.; Kiss, C.; Pál, A.; Santos-Sanz, P.; Stansberry, J.; Delsanti, A.; Vilenius, E.; Müller, T. G.; Peixinho, N.; Lellouch, E.; Szalai, N.; Henry, F.; Duffard, R.; Fornasier, S.; Hartogh, P.; Mueller, M.; Ortiz, J. L.; Protopapa, S.; Rengel, M.; Thirouin, A. (2012). "TNOs are cool: A survey of the trans-Neptunian region V. Physical characterization of 18 Plutinos using Herschel-PACS observations". Astronomy and Astrophysics. 541 (A93): A93. arXiv:1202.3657. Bibcode:2012A&A...541A..93M. doi:10.1051/0004-6361/201118562.
    13. Rubin, Alan E. (1995). "Petrologic evidence for collisional heating of chondritic asteroids". Icarus. 113 (1): 156–167. Bibcode:1995Icar..113..156R. doi:10.1006/icar.1995.1013.
    14. Walsh, Kevin J.; Morbidelli, Alessandro; Raymond, Sean N.; O'Brien, David P.; Mandell, Avi M. (2011). "A low mass for Mars from Jupiter's early gas-driven migration". Nature. 475 (206): 206–209. arXiv:1201.5177. Bibcode:2011Natur.475..206W. doi:10.1038/nature10201. PMID 21642961. S2CID 4431823.
    15. Raymond, Sean N.; Izidoro, Andre (2017). "Origin of water in the inner Solar System: Planetesimals scattered inward during Jupiter and Saturn's rapid gas accretion". Icarus. 297: 134–148. arXiv:1707.01234. Bibcode:2017Icar..297..134R. doi:10.1016/j.icarus.2017.06.030. S2CID 119031134.
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