5771 Somerville

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5771 Somerville
Discovery [1]
Discovered by E. Bowell
Discovery site Anderson Mesa Stn.
Discovery date 21 September 1987
MPC designation (5771) Somerville
Named after
Mary Somerville[2]
(Scottish polymath)
1987 ST1 · 1982 YY1
1989 BG1
main-belt · (outer)[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 34.36 yr (12,549 days)
Aphelion 3.8347 AU
Perihelion 2.4381 AU
3.1364 AU
Eccentricity 0.2226
5.55 yr (2,029 days)
0° 10m 38.64s / day
Inclination 8.2191°
Physical characteristics
Dimensions 22.84 km (derived)[3]
24.90±6.97 km[5]
26.43±5.87 km[6]
28.306±0.264 km[7]
33.60±2.18 km[8]
9.20±0.05 h[9][a]
0.0407 (derived)[3]
C [3]
12.20[7] · 12.30[1][3][6] · 12.40[8] · 12.50[5] · 12.94±0.26[10]

5771 Somerville, provisional designation 1987 ST1, is a carbonaceous Lixiaohua asteroid from the outer regions of the asteroid belt, approximately 26 kilometers in diameter. It was discovered on 21 September 1987, by American astronomer Edward Bowell at the Anderson Mesa Station of the Lowell Observatory in Flagstaff, Arizona.[11] The asteroid was named for Scottish polymath Mary Somerville.[2]

Orbit and classification[edit]

Somerville is a member of the Lixiaohua family,[4] an outer-belt asteroid family with more than 700 known members, consisting of C-type and X-type asteroids. The family's namesake is 3556 Lixiaohua.[12]:23

The asteroid orbits the Sun in the outer main-belt at a distance of 2.4–3.8 AU once every 5 years and 7 months (2,029 days). Its orbit has an eccentricity of 0.22 and an inclination of 8° with respect to the ecliptic.[1] Somerville was first identified as 1982 YY1 at Purple Mountain Observatory in December 1982. The body's observation arc begins with its official discovery observation at Flagstaff.[11]

Physical characteristics[edit]

Somerville is an assumed C-type asteroid.[3]

Rotation period[edit]

In March 2012, a rotational lightcurve of Somerville was obtained from photometric observations by American astronomer Brian Warner at his Palmer Divide Observatory (716) in Colorado. Lightcurve analysis gave a rotation period of 9.20 hours with a brightness amplitude of 0.80 magnitude (U=2+).[9][a]

Diameter and albedo[edit]

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Somerville measures between 24.90 and 33.60 kilometers in diameter and its surface has an albedo between 0.017 and 0.04.[5][6][7][8]

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0407 and a diameter of 22.84 kilometers based on an absolute magnitude of 12.3.[3]


This minor planet was named after Mary Somerville (1780–1872; née Fairfax), a Scottish polymath and science writer who studied mathematics and astronomy. She is considered to be one of Europe’s most distinguished women scientists of her time.[2] The official naming citation was published by the Minor Planet Center on 12 July (M.P.C. 25444).[13]


  1. ^ a b Lightcurve plot of (5771) Somerville, Palmer Divide Observatory, Brian D. Warner (2012), with a period of 9.20±0.05 hours and an amplitude (mag) of 0.80±0.03.


  1. ^ a b c d "JPL Small-Body Database Browser: 5771 Somerville (1987 ST1)" (2017-04-28 last obs.). Jet Propulsion Laboratory. Retrieved 9 September 2017. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (5771) Somerville. Springer Berlin Heidelberg. p. 488. ISBN 978-3-540-00238-3. Retrieved 9 September 2017. 
  3. ^ a b c d e f g "LCDB Data for (5771) Somerville". Asteroid Lightcurve Database (LCDB). Retrieved 9 September 2017. 
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 9 September 2017. 
  5. ^ a b c d Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923Freely accessible. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 9 September 2017. 
  6. ^ a b c d Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522Freely accessible. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 9 September 2017. 
  7. ^ a b c d Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794Freely accessible. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 9 September 2017. 
  8. ^ a b c d 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. Retrieved 9 September 2017. 
  9. ^ a b Warner, Brian D. (July 2012). "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2011 December - 2012 March". The Minor Planet Bulletin. 39 (3): 158–167. Bibcode:2012MPBu...39..158W. ISSN 1052-8091. Retrieved 9 September 2017. 
  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:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 9 September 2017. 
  11. ^ a b "5771 Somerville (1987 ST1)". Minor Planet Center. Retrieved 9 September 2017. 
  12. ^ Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv:1502.01628Freely accessible. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 9 September 2017. 
  13. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 9 September 2017. 

External links[edit]