1981 Midas
Radar images of Midas by the Arecibo Observatory in March 2018
Discovery[1]
Discovered byC. Kowal
Discovery sitePalomar Obs.
Discovery date6 March 1973
Designations
(1981) Midas
Pronunciation/ˈmaɪdəs/[2]
Named after
Midās (Greek mythology)[3]
1973 EA
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc41.97 yr (15,330 days)
Aphelion2.9307 AU
Perihelion0.6212 AU
1.7759 AU
Eccentricity0.6502
2.37 yr (864 days)
256.48°
0° 24m 59.4s / day
Inclination39.833°
356.90°
267.80°
Earth MOID0.0045 AU (1.8 LD)
Physical characteristics
Dimensions
5.22 h[7][8]
  • 0.2661 (derived)[6]
  • 0.293±0.025[5]

    1981 Midas, provisional designation 1973 EA, is a vestoid asteroid, classified as a near-Earth object and potentially hazardous asteroid, approximately 2 kilometers in diameter.[1]

    It was discovered on 6 March 1973 by American astronomer Charles Kowal at Palomar Observatory in San Diego County, California.[4] It was named after King Midas from Greek mythology.[3]

    Classification and orbit

    The moderately bright V-type asteroid is also an Apollo asteroid, as well as a Venus and Mars-crosser. The asteroid orbits the Sun at a distance of 0.6–2.9 AU once every 2 years and 4 months (864 days). Its orbit has an eccentricity of 0.65 and an inclination of 40° with respect to the ecliptic.[1]

    Midas has a low minimum orbit intersection distance with Earth of 0.0036 AU (540,000 km; 330,000 mi), which corresponds to 1.5 lunar distance (Earth–Moon distance). However, it does not pose an impact risk for the foreseeable future. On 19 March 1947 it passed 0.0298 AU (4,460,000 km; 2,770,000 mi) from Earth.[12] The last notable close approach was on 21 March 2018 passing 0.08957 AU (13,399,000 km; 8,326,000 mi) from Earth[12] and shining at an apparent magnitude of +12.4.[13] The next notable close approach will be on 14 September 2032 passing slightly closer at 0.08635 AU (12,918,000 km; 8,027,000 mi) from Earth.[12] As no precoveries are known, the asteroid's observation arc begins with its discovery observation at Palomar in 1973.[4]

    With a semi-major axis of 1.78 AU, when 1 AU from the Sun (and passing Earth's orbit) the asteroid is moving at 35.7 km/s with respect to the Sun.[lower-alpha 1] For comparison Earth orbits the Sun at 30 km/s.

    Physical characteristics

    Three rotational lightcurves obtained from photometric observations gave a concurring rotation period of 5.24 hours with a relatively high brightness variation of 0.65, 0.8 and 0.87 in magnitude, respectively (U=3/2/3).[8][7][9]

    According to the survey carried out by the Japanese Akari satellite, Midas measures 1.95 kilometers in diameter and its surface has an albedo of 0.293,[5] while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.266 and calculates an identical diameter of 1.95 kilometers with an absolute magnitude of 15.6.[6]

    In 1987, Midas was also detected by radar from Goldstone Deep Space Communications Complex at a distance of 0.08 AU with a measured maximal radar cross-section of 0.1 km2.[14]

    Naming

    This minor planet was named after the figure from Greek mythology, Midas, the King of Phrygia, who turned whatever he touched to gold. He received this ability as an award, but soon realized that this gift was a curse when his daughter turned into a statue after he had touched her. Relieved of his power by bathing in the river Pactolus, other accounts also tell his death caused by starvation.[3] The official naming citation was published by the Minor Planet Center on 15 October 1977 (M.P.C. 4237).[15]

    Notes

    1. ↑ v = 42.1219 √1/r − 0.5/a, where r is the distance from the Sun, and a is the major semi-axis. Objects move fastest at perihelion and slowest at aphelion.

    References

    1. 1 2 3 4 5 6 7 8 "JPL Small-Body Database Browser: 1981 Midas (1973 EA)" (2015-02-24 last obs.). Jet Propulsion Laboratory. Retrieved 1 July 2017.
    2. ↑ "Midas". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 4 February 2020.
    3. 1 2 3 Schmadel, Lutz D. (2007). "(1981) Midas". Dictionary of Minor Planet Names – (1981) Midas. Springer Berlin Heidelberg. p. 160. doi:10.1007/978-3-540-29925-7_1982. ISBN 978-3-540-00238-3.
    4. 1 2 3 "1981 Midas (1973 EA)". Minor Planet Center. Retrieved 18 September 2016.
    5. 1 2 3 4 Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
    6. 1 2 3 4 5 "LCDB Data for (1981) Midas". Asteroid Lightcurve Database (LCDB). Retrieved 18 September 2016.
    7. 1 2 3 Mottola, S.; de Angelis, G.; di Martino, M.; Erikson, A.; Harris, A. W.; Hahn, G.; Neukum, G.; Pravec, P.; Wolf, M. (March 1995). "The EUNEASO Photometric Follow-up Program". Abstracts of the Lunar and Planetary Science Conference. 26: 1003. Bibcode:1995LPI....26.1003M.
    8. 1 2 Torppa, J.; Aksnes, K.; Dai, Z.; Grav, T.; Hahn, G.; Laakso, T.; Lagerkvist, C.-I.; Muinonen, K.; et al. (August 2005). "Spins and Shapes of Potentially Hazardous Asteroids". American Astronomical Society. 37: 643. Bibcode:2005DPS....37.1526T.
    9. 1 2 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. 26: 1511. Bibcode:1995LPI....26.1511W.
    10. ↑ 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.
    11. ↑ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 – Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007.
    12. 1 2 3 "JPL Close-Approach Data: 1981 Midas (1973 EA)" (2013-12-30 last obs). Archived from the original on 28 August 2020. Retrieved 31 January 2014.
    13. ↑ "(1981) Midas Ephemerides for 15 Feb 2018 through 15 Apr 2018". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 31 January 2014.
    14. ↑ Ostro, S. J.; Jurgens, R. F.; Rosema, K. D.; Winkler, R.; et al. (October 1991). "Asteroid radar astrometry". Astronomical Journal. 102: 1490–1502. Bibcode:1991AJ....102.1490O. doi:10.1086/115975.
    15. ↑ Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.
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