14827 Hypnos

14827 Hypnos (prov. designation: 1986 JK) is a highly eccentric, sub-kilometer-sized carbonaceous asteroid that is thought to be an extinct comet. It is classified as near-Earth object and potentially hazardous asteroid of the Apollo group.

14827 Hypnos
Discovery [1]
Discovered byC. S. Shoemaker
E. M. Shoemaker
Discovery sitePalomar Obs.
Discovery date5 May 1986
Designations
(14827) Hypnos
Pronunciation/ˈhɪpnɒs/
Named after
Hypnos [2]
(Greek god of sleep)
1986 JK
Apollo · NEO · PHA [1][3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc19.32 yr (7,058 days)
Aphelion4.7318 AU
Perihelion0.9491 AU
2.8405 AU
Eccentricity0.6659
4.79 yr (1,749 days)
206.81°
0° 12m 21.24s / day
Inclination1.9808°
57.976°
238.09°
Earth MOID0.0147 AU · 5.7 LD
Jupiter MOID0.5249 AU
Physical characteristics
Mean diameter
0.520±0.260 km[4]
> 0.74 km[5]
0.9 km (Gehrels 1994)[1]
0.907 km (derived)[6]
0.057 (assumed)[6]
< 0.067 (radar)[5]
0.22±0.17[4]
C [5][6]
B–V = 0.684 [1]
U–B = 0.492 [1]
18.3[1] · 18.65±0.22[4] · 18.94[6][7]

    The asteroid was discovered by American astronomer couple Carolyn and Eugene Shoemaker at the Palomar Observatory in California on 5 May 1986.[3] It was named after Hypnos, the Greek god of sleep.[2]

    Orbit and classification
    Comet-like orbit of Hypnos with a high eccentricity of 0.67

    Hypnos orbits the Sun at a distance of 0.9–4.7 AU once every 4 years and 9 months (1,749 days). Its orbit has a high eccentricity of 0.67 and an inclination of 2° with respect to the ecliptic.[1] It is frequently perturbed by Jupiter.[8]

    The body's observation arc begins at Anderson Mesa Station the night prior to its official discovery observation at Palomar.[3]

    Close approaches

    As a near-Earth object and potentially hazardous asteroid Hypnos has an Earth minimum orbital intersection distance of 0.0147 AU (2,200,000 km), which corresponds to 5.7 lunar distances.[1]

    In 1958, Hypnos passed less than 0.03 AU from both Earth and Mars.[9] Neither planet has been approached so closely by Hypnos since the 862 AD pass of Earth, or will be until the 2214 pass of Earth. It is also a Mars-crosser.

    Extinct comet

    Hypnos may be the nucleus of an extinct comet that is covered by a crust several centimeters thick that prevents any remaining volatiles from outgassing.[10]

    Physical characteristics

    Hypnos is an assumed carbonaceous C-type asteroid.[6][5]

    Lightcurves

    As of 2018, no rotational lightcurve of Hypnos has been obtained from photometric observations. The asteroids rotation period and spin axis remains unknown.[6] It has a low brightness amplitude of 0.05 magnitude which indicates that the body has a rather spheroidal shape.[7]

    Diameter and albedo

    According to the NEOSurvey carried out by NASA's Spitzer Space Telescope, Hypnos measures 520 meters in diameter and its surface has an albedo of 0.22 based on an absolute magnitude of 18.65,[4] while infrared radiometry gave a radar albedo of no more than 0.067 and a diameter of at least 740 meters.[5]

    The Collaborative Asteroid Lightcurve Link assumes a standard optical albedo for carbonaceous asteroids 0.057 and derives a diameter of 907 meters with an absolute magnitude of 18.94.[6] The diameter agrees with Tom Gehrels 1994-publication Hazards due to Comets and Asteroids in which he estimated a mean-diameter of 900 meters for Hypnos.[1]

    Naming

    This minor planet was named after Hypnos from Greek mythology. He is the god of sleep, son of Nyx and Erebus and twin brother of Thanatos. He enters the sleep of mortals and gives them dreams of foolishness or inspiration.[2] The English word "hypnosis" is derived from his name. The official naming citation was published by the Minor Planet Center on 6 January 2003 (M.P.C. 47301).[11]

    References
    1. "JPL Small-Body Database Browser: 14827 Hypnos (1986 JK)" (2005-08-30 last obs.). Jet Propulsion Laboratory. Retrieved 12 September 2017.
    2. Schmadel, Lutz D. (2006). "(14827) Hypnos [2.84, 0.67, 2.0]". Dictionary of Minor Planet Names – (14827) Hypnos, Addendum to Fifth Edition: 2003–2005. Springer Berlin Heidelberg. p. 88. doi:10.1007/978-3-540-34361-5_896. ISBN 978-3-540-34361-5.
    3. "14827 Hypnos (1986 JK)". Minor Planet Center. Retrieved 12 September 2017.
    4. Trilling, David E.; Mommert, Michael; Hora, Joseph; Chesley, Steve; Emery, Joshua; Fazio, Giovanni; et al. (December 2016). "NEOSurvey 1: Initial Results from the Warm Spitzer Exploration Science Survey of Near-Earth Object Properties". The Astronomical Journal. 152 (6): 10. arXiv:1608.03673. Bibcode:2016AJ....152..172T. doi:10.3847/0004-6256/152/6/172.
    5. Lance Benner (3 April 2012). "NEA Radar Albedo Ranking". Asteroid Radar Research. Retrieved 12 September 2017.
    6. "LCDB Data for (14827) Hypnos". Asteroid Lightcurve Database (LCDB). Retrieved 12 September 2017.
    7. Wisniewski, W. Z. (June 1987). "Photometry of six radar target asteroids". Icarus. 70 (3): 566–572. Bibcode:1987Icar...70..566W. doi:10.1016/0019-1035(87)90096-0. ISSN 0019-1035. Retrieved 12 September 2017.
    8. "JPL Close-Approach Data: 14827 Hypnos (1986 JK)" (last observation: 2000-10-25). Retrieved 6 May 2009.
    9. "NEODys (14827) Hypnos". Department of Mathematics, University of Pisa. Retrieved 12 September 2017.
    10. Whitman, Kathryn; Morbidelli, Alessandro; Jedicke, Robert (July 2006). "The size frequency distribution of dormant Jupiter family comets". Icarus. 183 (1): 101–114. arXiv:astro-ph/0603106. Bibcode:2006Icar..183..101W. CiteSeerX 10.1.1.256.3946. doi:10.1016/j.icarus.2006.02.016. Retrieved 12 September 2017.
    11. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 12 September 2017.
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