| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 26 February 1928 |
| Designations | |
| (1091) Spiraea | |
| Pronunciation | /spaɪˈriːə/[2] |
Named after | Spiraea (genus ofshrubs)[3] |
| 1928 DT · 1934 CN1 1938 UR · 1964 XH | |
| main-belt · (outer)[1][4] Cybele · background[5] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 89.27 yr (32,606 days) |
| Aphelion | 3.6484AU |
| Perihelion | 3.2077 AU |
| 3.4281 AU | |
| Eccentricity | 0.0643 |
| 6.35yr (2,318 days) | |
| 110.37° | |
| 0° 9m 19.08s / day | |
| Inclination | 1.1554° |
| 80.790° | |
| 12.062° | |
| Physical characteristics | |
| Dimensions | 32.78 km(calculated)[4] 35.178±0.108 km[6] 39.92±17.85 km[7] 40.280±0.455 km[8] 40.52±0.91 km[9] |
| 7.01±0.43h[10] | |
| 0.05±0.06[7] 0.057(assumed)[4] 0.0627±0.0106[8] 0.063±0.003[9] 0.091±0.025[6] | |
| C(assumed)[4] | |
| 10.60[8][9] · 10.70±0.08(R)[10] · 10.8[1] · 11.00±0.14[11] · 11.15[4] · 11.18[7] | |
1091 Spiraea, provisional designation1928 DT, is a carbonaceous Cybeleasteroid from the outer regions of theasteroid belt, approximately 36 kilometers in diameter. It was discovered on 26 February 1928, by astronomerKarl Reinmuth at theHeidelberg-Königstuhl State Observatory in southwest Germany.[12] The asteroid was named afterSpiraea, a genus of plants.[3]
Spiraea orbits the Sun in theouter main-belt at a distance of 3.2–3.6 AU once every 6 years and 4 months (2,318 days). Its orbit has aneccentricity of 0.06 and aninclination of 1° with respect to theecliptic.[1] With these orbital parameters, it belongs to theCybele asteroids, a dynamical group near the 4:7resonance with Jupiter and named after one of the largest asteroids,65 Cybele. It is, however, a non-family asteroid from the main belt'sbackground population when applying thehierarchical clustering method (Nesvorny, Novakovic, Knezevic and Milani) to its proper orbital elements.[5]
The body'sobservation arc begins with its identification as1934 CN1 atUccle Observatory in February 1934, almost six years after its official discovery observation at Heidelberg.[12]
Spiraea is an assumed carbonaceousC-type asteroid.[4]
In December 2014, a fragmentary rotationallightcurve ofSpiraea was obtained from photometric observations in the R-band by astronomers at thePalomar Transient Factory in California. Lightcurve analysis gave arotation period of 7.01 hours with a brightness amplitude of 0.03magnitude (U=1+).[10]
According to the surveys carried out by the JapaneseAkari satellite and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Spiraea measures between 35.178 and 40.52 kilometers in diameter and its surface has analbedo between 0.05 and 0.091.[6][7][8][9]
TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 32.78 kilometers based on anabsolute magnitude of 11.15.[4]
Thisminor planet was named afterSpiraea, a genus ofshrubs of the rose family (Rosaceae), with small white or pink flowers. The official naming citation was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 103).[3]
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 with1054 Forsytia, that were all named after plants, in particularflowering plants(also see list of minor planets named after animals and plants).[13]
