4197 Morpheus

4197 Morpheus, provisional designation 1982 TA, is a highly eccentric asteroid and near-Earth object of the Apollo group, approximately 3 kilometers in diameter. It was discovered on 11 October 1982, by American astronomers Eleanor Helin and Eugene Shoemaker at Palomar Observatory in California, United States. The asteroid was later named for Morpheus from Greek mythology.[3]

4197 Morpheus
Discovery [1]
Discovered byE. F. Helin
E. Shoemaker
Discovery sitePalomar Obs.
Discovery date11 October 1982
Designations
(4197) Morpheus
Pronunciation/ˈmɔːrfiːəs/[2]
Named after
Morpheus
(mythology and movie)[3]
1982 TA
Apollo · NEO
Mars-crosser
Venus-crosser
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc61.98 yr (22,639 days)
Earliest precovery date3 September 1954
Aphelion4.0690 AU
Perihelion0.5246 AU
2.2968 AU
Eccentricity0.7716
3.48 yr (1,271 days)
339.88°
0° 16m 59.16s / day
Inclination12.577°
7.1844°
122.40°
Earth MOID0.0987 AU · 38.5 LD
Physical characteristics
Mean diameter
1.8 km (dated)[1]
2.20 km (dated)[4]
2.98 km (taken)[5]
2.981 km[6]
3.043±0.156 km[7]
3.5372 h[8]
3.5380 h[9]
3.5387 h[10]
3.540±0.001 h[11]
3.560 h[12]
0.2389[5][6]
0.276±0.077[7]
0.44[4]
SMASS = Sq [1] · S [5]
14.6[1][7] · 14.8[4][5][6][11] · 14.88[9]

    Orbit and classification

    Morpheus orbits the Sun at a distance of 0.5–4.1 AU once every 3 years and 6 months (1,271 days). Its orbit has an eccentricity of 0.77 and an inclination of 13° with respect to the ecliptic.[1] Due to this elongated orbit, the asteroid is both, a Mars-crosser and a Venus-crosser.

    It has a minimum orbit intersection distance with Earth of 0.0987 AU (14,800,000 km), which corresponds to 38.5 lunar distances.[1]

    A first precovery was taken at the discovering observatory in 1954, extending the body's observation arc by 28 years prior to its official discovery observation.[3]

    Physical characteristics

    On the SMASS taxonomic scheme, Morpheus is classified as a stony Sq sub-type, which transitions from the common S-type to the rather rare Q-type asteroids.[1]

    Diameter and albedo

    In the 1990s, Tom Gehrels gave a first diameter estimate for Morpheus of 1.8 kilometers.[1] According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), it measures 3.043 kilometers in diameter and its surface has an albedo of 0.276.[7] In 2012, a revision of the published WISE-data by Petr Pravec gave a diameter of 2.981 kilometers and an albedo of 0.2389.[6] The Collaborative Asteroid Lightcurve Link adopts the revised WISE-data and takes a diameter of 2.98 kilometers with an absolute magnitude of 14.8.[5]

    Rotation and shape

    In 1996, a rotational lightcurve was obtained by Czech astronomer Petr Pravec at the Ondřejov Observatory during the body's close approach to Earth within 0.1 AU. It gave a well-defined rotation period of 3.5380 hours with a brightness variation of 0.49 magnitude (U=3).[9]

    At the same time, astronomers at the Goldstone Observatory analysed Morpheus using radar delay-Doppler imaging. The resultant images are not very clear, but they show that the body has a roughly triangular shape, and a 3-hour rotation period.

    Seven years later, during the asteroid's next close approach in 2003, Morpheus was observed for five nights by Slovak astronomer Adrián Galád at the Modra Observatory. Lightcurve analysis showed a concurring period of 3.5387 hours and an amplitude of 0.4 in magnitude (U=3).[10]

    Naming

    This minor planet was named after Morpheus from Greek mythology. He is a god of dreams who appears in the poem Metamorphoses written by the Roman poet Ovid. He is capable to imitate any human form and to appear in dreams.

    Morpheus is also the name of one of the characters in the franchise The Matrix.[3] The approved naming citation was published by the Minor Planet Center on 5 January 2015 (M.P.C. 91790).[13]

    References
    1. "JPL Small-Body Database Browser: 4197 Morpheus (1982 TA)" (2016-08-27 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2017.
    2. "Morpheus". Lexico UK Dictionary. Oxford University Press.
    3. "4197 Morpheus (1982 TA)". Minor Planet Center. Retrieved 1 March 2016.
    4. Harris, Alan W. (February 1998). "A Thermal Model for Near-Earth Asteroids". Icarus. 131 (2): 291–301. Bibcode:1998Icar..131..291H. doi:10.1006/icar.1997.5865. Retrieved 1 March 2016.
    5. "LCDB Data for (4197) Morpheus". Asteroid Lightcurve Database (LCDB). Retrieved 25 May 2016.
    6. Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026. Retrieved 1 March 2016.
    7. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 25 May 2016.
    8. Prokof'eva, V. V.; Gaftonyuk, N. M.; Tarashchuk, V. P. (September 2001). "Three Periods in Asteroid 4197 Brightness Variations". Solar System Research (5): 383–389. Bibcode:2001SoSyR..35..383P. Retrieved 1 March 2016.
    9. Pravec, P.; S˘ arounová, L.; Wolf, M.; Ferrin, I. R. Vasquez; Zhu, J. (January 2000). "CCD photometry of asteroids (4197) 1982 TA and 1997 LY 4". Planetary and Space Science. 48 (1): 59–65. Bibcode:2000P&SS...48...59P. doi:10.1016/S0032-0633(99)00073-2. Retrieved 1 March 2016.
    10. Galád, A.; Kornos, L.; Gajdos, S.; Világi, J.; Tóth, J. (October 2004). "Relative photometry of numbered asteroids (3712), (4197), (5587), (28753) and (66063)". Contributions of the Astronomical Observatory Skalnaté Pleso: 157–166. Bibcode:2004CoSka..34..157G. Retrieved 1 March 2016.
    11. Wisniewski, W. Z.; Michalowski, T. M.; Harris, A. W.; McMillan, R. S. (March 1995). "Photoelectric Observations of 125 Asteroids". Abstracts of the Lunar and Planetary Science Conference. Bibcode:1995LPI....26.1511W. Retrieved 1 March 2016.
    12. Hoffmann, Martin; Rebhan, Helge; Neukum, Gerhard; Geyer, Edward H. (January 1993). "Photometric observations of four near-earth asteroids". Acta Astronomica: 61–67. Bibcode:1993AcA....43...61H. ISSN 0001-5237. Retrieved 1 March 2016.
    13. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 25 May 2016.
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