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. ^[12] The asteroid was named after Spiraea, a genus of plants. ^[3]

Orbit and classification

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, Novakovic, Knezevic and Milani) to its proper orbital elements. ^[5]

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. ^[12]

Physical characteristics

Spiraea is an assumed carbonaceous C-type asteroid. ^[4]

Rotation period

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+). ^[10]

Diameter and albedo

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. ^{[6] [7] [8] [9]}

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. ^[4]

Naming

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). ^[3]

Reinmuth's flowers

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). ^[13]

References

External links

• Asteroid Lightcurve Database (LCDB), query form ( info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 1091 Spiraea at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 1091 Spiraea at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters