2815 Soma

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2815 Soma
Discovery [1]
Discovered byE. Bowell
Discovery siteAnderson Mesa Stn.
Discovery date15 September 1982
MPC designation(2815) Soma
Named after
Soma cube
(mechanical puzzle)[2]
1982 RL · 1955 MH
1970 AC · 1974 DL
1979 XB1
main-belt · Flora[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc61.77 yr (22,562 days)
Aphelion2.6107 AU
Perihelion1.8552 AU
2.2329 AU
3.34 yr (1,219 days)
0° 17m 43.44s / day
Known satellites1[3][4][5]
(Ds/Dp: 0.25±0.02)
(orbital period: 17.915 h
Physical characteristics
Dimensions6.641±0.105 km[6]
7.067 km[7]
7.07 km (taken)[3]
7.158±0.088 km[8]
2.7327±0.0008 h[a]
2.73325±0.00007 h[4]
12.49±0.06 (R)[a] · 12.53±0.02 (R)[4] · 12.6[8] · 12.7[1] · 12.92±0.16[9] · 12.98±0.078[3][7]

2815 Soma, provisional designation 1982 RL, is a binary Florian asteroid from the inner regions of the asteroid belt, approximately 7 kilometers in diameter. It was discovered on 15 September 1982, by American astronomer Edward Bowell at Lowell's Anderson Mesa Station in Flagstaff, Arizona, in the United States .[10] It is named for the mechanical puzzle Soma cube.[2]

Orbit and classification[edit]

Soma is a member of the Flora family, a large family of stony asteroids. It orbits the Sun in the inner main-belt at a distance of 1.9–2.6 AU once every 3 years and 4 months (1,219 days). Its orbit has an eccentricity of 0.17 and an inclination of 6° with respect to the ecliptic.[1] It was first identified as 1955 MH at Goethe Link Observatory in 1955. The body's observation arc begins with 1970 AC at Crimea-Nauchnij, 12 years prior to its official discovery at Anderson Mesa.[10]

Diameter and albedo[edit]

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer (WISE) with its subsequent NEOWISE mission, Soma measures 6.641 and 7.158 kilometers in diameter and its surface has an albedo of 0.365 and 0.3207, respectively.[6][8] The Collaborative Asteroid Lightcurve Link adopts Peter Pravec's revised WISE-data, that is, an albedo of 0.2273 and a diameter of 7.067 kilometers with an absolute magnitude of 12.98.[3][7]

Moon and lightcurve[edit]


In November 2009, a rotational lightcurve of Soma was obtained from photometric observations by astronomers Petr Pravec, Donald Pray and Peter Kušnirák at Carbuncle Hill Observatory, Rhode Island, and Ondřejov Observatory, in the Czech Republic, respectively. Lightcurve analysis gave a rotation period of 2.7327 hours with a brightness variation of 0.08 magnitude, indicating that the body has a nearly spheroidal shape (U=3-).[a] The body's spin rate is within the 2.2-to-20 hours range found for most asteroids, about half an hour longer than the so-called fast rotators.


In March 2011, photometric observations revealed that Soma is a synchronous binary asteroid with a minor-planet moon orbiting it every 17.915 hours. The system has a secondary-to-primary mean-diameter ratio of 0.25, which means that satellite's diameter measures approximately 25% of that of Soma (the primary), and translate into a diameter of 1.75 kilometers.[4] The observations also gave a refined rotation period for Soma of 2.73325 hours and an amplitude of 0.07 magnitude (U=n.a.). The system has an absolute magnitude of 12.53, and a phase slope parameter (G) of 0.27.[4]


This minor planet was named for the Soma cube, following a proposal by Belgian astronomer Jean Meeus (also see 2213 Meeus). The Soma cube a dissection puzzle with seven pieces, invented by the Danish mathematician Piet Hein and popularized by American writer Martin Gardner (also see 2587 Gardner).[2] The approved naming citation was published by the Minor Planet Center on 10 September 1984 (M.P.C. 9080).[11]


  1. ^ a b c Pravec (2009) web: lightcurve plot of (2815) Soma with rotation period 2.7327±0.0008 hours and a brightness amplitude of 0.08 magnitude. Quality Code of 3-. Summary figures at Collaborative Asteroid Lightcurve Link and data sheet from the Ondrejov Asteroid Photometry Project


  1. ^ a b c d "JPL Small-Body Database Browser: 2815 Soma (1982 RL)" (2017-03-30 last obs.). Jet Propulsion Laboratory. Retrieved 3 July 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). "(2815) Soma". Dictionary of Minor Planet Names – (2815) Soma. Springer Berlin Heidelberg. p. 231. doi:10.1007/978-3-540-29925-7_2816. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f "LCDB Data for (2815) Soma". Asteroid Lightcurve Database (LCDB). Retrieved 23 March 2017.
  4. ^ a b c d e Pollock, J.; Pravec, P.; Kusnirak, P.; Hornoch, K.; Chiorny, V.; Gajdos, S.; et al. (April 2011). "(2815) Soma". Central Bureau Electronic Telegrams. 2705 (2705): 1. Bibcode:2011CBET.2705....1P. Retrieved 23 March 2017.
  5. ^ Johnston, Robert (21 September 2014). "(2815) Soma". johnstonsarchive.net. Retrieved 23 March 2017.
  6. ^ a b c Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 23 March 2017.
  7. ^ a b c d 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 23 March 2017.
  8. ^ a b c d 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.
  9. ^ 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. Retrieved 23 March 2017.
  10. ^ a b "2815 Soma (1982 RL)". Minor Planet Center. Retrieved 23 March 2017.
  11. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 23 March 2017.

External links[edit]