4486 Mithra

4486 Mithra (prov. designation: 1987 SB), is an eccentric asteroid and suspected contact-binary, classified as near-Earth object and potentially hazardous asteroid, approximately 2 kilometers in diameter. It belongs to the Apollo group of asteroids and is a relatively slow rotator.

4486 Mithra
Discovery [1]
Discovered by
Discovery siteRozhen Obs. – Smolyan
Discovery date22 September 1987
Designations
(4486) Mithra
Pronunciation/ˈmɪθrə/[2]
Named after
Mithra
(proto-Indo-Iranian religion)[3]
  • 1987 SB
  • 1974 DN1
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc29.04 yr (10,607 days)
Aphelion3.6582 AU
Perihelion0.7417 AU
2.2000 AU
Eccentricity0.6629
3.26 yr (1,192 days)
91.928°
0° 18m 7.2s / day
Inclination3.0395°
82.240°
168.87°
Earth MOID0.0463 AU (18 LD)
Physical characteristics
Mean diameter
  • 1.849±0.022 km[5][6]
  • 2.25 km (calculated)[7]
S [7]

    The asteroid was discovered on 22 September 1987, by Belgian astronomer Eric Elst and Bulgarian astronomer Vladimir Shkodrov at Rozhen Observatory, in the Smolyan Province of Bulgaria.[4] It was named after the Indo-Iranian divinity Mithra.[3]

    Orbit and classification

    Mithra orbits the Sun at a distance of 0.7–3.7 AU once every 3 years and 3 months (1,192 days). Its orbit has an eccentricity of 0.66 and an inclination of 3° with respect to the ecliptic.[1] In 1974, Mithra was first identified as 1974 DN1 at Crimea–Nauchnij. The body's observation arc begins 8 months prior to its official discovery observation, with a precovery taken at the Japanese Kiso Observatory in January 1987.[4]

    Close approaches

    As a potentially hazardous asteroid, it has a low minimum orbit intersection distance with Earth of 0.0463 AU (6,930,000 km) or 18 lunar distances.[1] On 14 August 2000, it passed 0.0465 AU (6,960,000 km) from Earth.[11]

    Physical characteristics

    Rotation period and shape

    Radar imaging using a delay-Doppler technique at the Arecibo and Goldstone observatories rendered a rotation period of 67.5±6 hours.[8] Based on the radar analysis, Mithra is also a strong candidate for a contact binary, which is composed of two distinct lobes in mutual contact, held together by their weak gravitational attraction. They typically show a bifurcated, dumbbell-like shape (also see 4769 Castalia).[8][12] A large number of near-Earth objects are believed to be contact-binaries.[13]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Mithra measures 1.85 kilometers in diameter and its surface has a high albedo of 0.297, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 2.25 kilometer with an absolute magnitude of 15.6.[5][6][7]

    Naming

    This minor planet was named after Mithra (also see Mitra), deity in the proto-Indo-Iranian religion. The mystery religion of Mithraism was practiced in the Roman Empire between the 1st and 4th century. Considered to be a rival of early Christianity, both religions shared similar characteristics such as elevation and the ritual of baptism. In the Hellenistic world, Mithra was conflated with Apollo. The asteroid 1862 Apollo is the namesake of this asteroid's orbital group.[3] The approved naming citation was published by the Minor Planet Center on 5 September 1990 (M.P.C. 16885).[14]

    References
    1. "JPL Small-Body Database Browser: 4486 Mithra (1987 SB)" (2016-02-13 last obs.). Jet Propulsion Laboratory. Retrieved 4 July 2017.
    2. "Mithras, Mithra". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
    3. Schmadel, Lutz D. (2007). "(4486) Mithra". Dictionary of Minor Planet Names – (4486) Mithra. Springer Berlin Heidelberg. p. 386. doi:10.1007/978-3-540-29925-7_4429. ISBN 978-3-540-00238-3.
    4. "4486 Mithra (1987 SB)". Minor Planet Center. Retrieved 10 August 2016.
    5. 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.
    6. Mainzer, A.; Grav, T.; Bauer, J.; Masiero, J.; McMillan, R. S.; Cutri, R. M.; et al. (December 2011). "NEOWISE Observations of Near-Earth Objects: Preliminary Results". The Astrophysical Journal. 743 (2): 17. arXiv:1109.6400. Bibcode:2011ApJ...743..156M. doi:10.1088/0004-637X/743/2/156.
    7. "LCDB Data for (4486) Mithra". Asteroid Lightcurve Database (LCDB). Retrieved 10 August 2016.
    8. Brozovic, Marina; Benner, Lance A. M.; Magri, Christopher; Ostro, Steven J.; Scheeres, Daniel J.; Giorgini, Jon D.; et al. (July 2010). "Radar observations and a physical model of contact binary Asteroid 4486 Mithra" (PDF). Icarus. 208 (1): 207–220. Bibcode:2010Icar..208..207B. doi:10.1016/j.icarus.2010.01.035.
    9. Ostro, S. J.; Hudson, R. S.; Benner, L. A. M.; Nolan, M. C.; Margot, J.-L.; Giorgini, J. D.; et al. (October 2000). "Radar Observations of Asteroid 4486 Mithra". American Astronomical Society. 32: 1003. Bibcode:2000DPS....32.0807O.
    10. 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.
    11. "JPL Small-Body Database Browser: 4486 Mithra (1987 SB)". Jet Propulsion Laboratory. Retrieved 10 August 2016.
    12. Lance A. M. Benner (18 November 2013). "Binary and Ternary near-Earth Asteroids detected by radar". NASA/JPL Asteroid Radar Research. Retrieved 1 March 2014.
    13. Michael Busch (12 March 2012). "Near-Earth Asteroids and Radar Speckle Tracking" (PDF). Retrieved 10 August 2016.
    14. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 10 August 2016.
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