1091 Spiraea

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1091 Spiraea
Discovery [1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date26 February 1928
MPC designation(1091) Spiraea
Named after
(genus of shrubs)[2]
1928 DT · 1934 CN1
1938 UR · 1964 XH
main-belt · (outer)[1][3]
Cybele · background [4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc89.27 yr (32,606 days)
Aphelion3.6484 AU
Perihelion3.2077 AU
3.4281 AU
6.35 yr (2,318 days)
0° 9m 19.08s / day
Physical characteristics
Dimensions32.78 km (calculated)[3]
35.178±0.108 km[5]
39.92±17.85 km[6]
40.280±0.455 km[7]
40.52±0.91 km[8]
7.01±0.43 h[9]
0.057 (assumed)[3]
C (assumed)[3]
10.60[7][8] · 10.70±0.08 (R)[9] · 10.8[1] · 11.00±0.14[10] · 11.15[3] · 11.18[6]

1091 Spiraea, provisional designation 1928 DT, is a carbonaceous Cybele asteroid from the outer regions of the asteroid belt, approximately 36 kilometers in diameter. It was discovered on 26 February 1928, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany.[11] The asteroid was named after Spiraea, a genus of plants.[2]

Orbit and classification[edit]

Spiraea orbits the Sun in the outer main-belt at a distance of 3.2–3.6 AU once every 6 years and 4 months (2,318 days). Its orbit has an eccentricity of 0.06 and an inclination of 1° with respect to the ecliptic.[1] With these orbital parameters, it belongs to the Cybele asteroids, a dynamical group near the 4:7 resonance with Jupiter and named after one of the largest asteroids, 65 Cybele. It is, however, a non-family asteroid from the main belt's background population when applying the Hierarchical Clustering Method (Nesvorny, 2015) to its proper orbital elements.[4]

The body's observation arc begins with its identification as 1934 CN1 at Uccle Observatory in February 1934, almost six years after its official discovery observation at Heidelberg.[11]

Physical characteristics[edit]

Spiraea is an assumed carbonaceous C-type asteroid.[3]

Rotation period[edit]

In December 2014, a fragmentary rotational lightcurve of Spiraea was obtained from photometric observations in the R-band by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 7.01 hours with a brightness amplitude of 0.03 magnitude (U=1+).[9]

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, Spiraea measures between 35.178 and 40.52 kilometers in diameter and its surface has an albedo between 0.05 and 0.091.[5][6][7][8]

The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 32.78 kilometers based on an absolute magnitude of 11.15.[3]


This minor planet was named after Spiraea, a genus of shrubs of the rose family (Rosaceae), with small white or pink flowers. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 103).[2]

Reinmuth's flowers[edit]

Due to his many discoveries, Karl Reinmuth submitted a large list of 66 newly named asteroids in the early 1930s. The list covered his discoveries with numbers between (1009) and (1200). This list also contained a sequence of 28 asteroids, starting with 1054 Forsytia, that were all named after plants, in particular flowering plants (also see list of minor planets named after animals and plants).[12]


  1. ^ a b c d e "JPL Small-Body Database Browser: 1091 Spiraea (1928 DT)" (2017-06-04 last obs.). Jet Propulsion Laboratory. Retrieved 26 September 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). "(1091) Spiraea". Dictionary of Minor Planet Names – (1091) Spiraea. Springer Berlin Heidelberg. p. 93. doi:10.1007/978-3-540-29925-7_1092. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f g "LCDB Data for (1091) Spiraea". Asteroid Lightcurve Database (LCDB). Retrieved 26 September 2017.
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 25 September 2017.
  5. ^ 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 26 September 2017.
  6. ^ 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:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 26 September 2017.
  7. ^ 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.
  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 26 September 2017.
  9. ^ a b c Chang, Chan-Kao; Lin, Hsing-Wen; Ip, Wing-Huen; Prince, Thomas A.; Kulkarni, Shrinivas R.; Levitan, David; et al. (December 2016). "Large Super-fast Rotator Hunting Using the Intermediate Palomar Transient Factory". The Astrophysical Journal Supplement Series. 227 (2): 13. arXiv:1608.07910. Bibcode:2016ApJS..227...20C. doi:10.3847/0067-0049/227/2/20. Retrieved 26 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:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 26 September 2017.
  11. ^ a b "1091 Spiraea (1928 DT)". Minor Planet Center. Retrieved 26 September 2017.
  12. ^ Schmadel, Lutz D. (2007). "(1054) Forsytia". Dictionary of Minor Planet Names – (1054) Forsytia. Springer Berlin Heidelberg. p. 90. doi:10.1007/978-3-540-29925-7_1055. ISBN 978-3-540-00238-3.

External links[edit]