1669 Dagmar
Rare-type Themistian asteroid
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1669 Dagmar, provisional designation 1934 RS, is a rare-type Themistian asteroid from the outer region of the asteroid belt, approximately 42 kilometers in diameter. It was discovered on 7 September 1934, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany, and named after a common German feminine name.[2][11]
| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 7 September 1934 |
| Designations | |
| (1669) Dagmar | |
Named after | Generic name (common German name)[2] |
| 1934 RS · 1943 GE 1950 PX · 1953 AD 1957 WA · 1959 CV 1962 RH | |
| main-belt · Themis[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 82.66 yr (30,190 days) |
| Aphelion | 3.4870 AU |
| Perihelion | 2.7920 AU |
| 3.1395 AU | |
| Eccentricity | 0.1107 |
| 5.56 yr (2,032 days) | |
| 126.58° | |
| 0° 10m 37.92s / day | |
| Inclination | 0.9409° |
| 18.979° | |
| 178.21° | |
| Physical characteristics | |
| Dimensions | 35.78±2.4 km (IRAS:17)[4] 42.377±0.188 km[5] 42.99±2.86 km[6] 43.00±0.77 km[7] 45.194±0.620 km[8] |
| Mass | (3.98±0.80)Ã1016 kg[6] |
Mean density | 0.95±0.27 g/cm3[6] |
| 12 h[9] | |
| 0.0354±0.0061[8] 0.039±0.007[5][7] 0.0565±0.008 (IRAS:17)[4] | |
| Tholen = G:[1] · G:[3] BâV = 0.730[1] UâB = 0.460[1] | |
| 10.91±0.18[10] · 10.97 (IRAS:17)[1][3][4] · 10.97[7][8] | |
Classification and orbit
The asteroid is a member of the Themis family, a large group of asteroids in the outer main-belt. It orbits the Sun at a distance of 2.8â3.5 AU once every 5 years and 7 months (2,032 days). Its orbit has an eccentricity of 0.11 and an inclination of 1° with respect to the ecliptic.[1] As no precoveries were taken, and no prior identifications were made, Dagmar's observation arc begins with its official discovery observation.[11]
Physical characteristics
Dagmar has a rare spectra of a G-type asteroid (or Cg-type in the SMASS taxonomy), similar to 1 Ceres, the largest asteroid and only dwarf planet in the asteroid belt.[1]
Rotation period
Astronomer Federico Manzini obtained a provisional lightcurve of Dagmar from photometric observations in March 2004. It gave a tentative rotation period of 12 hours with a brightness variation of 0.15 magnitude (U=1).[9] As of 2017, no secure period has yet been published.[1]
Diameter and albedo
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Dagmar measures between 35.78 and 45.194 kilometers in diameter, and its surface has an albedo between 0.035 and 0.057.[4][5][7][8] The Collaborative Asteroid Lightcurve Link adopts the results obtained by 17 observations made by IRAS, that is an albedo of 0.0565 and a diameter of 35.78 kilometers with an absolute magnitude of 10.97.[3]
Naming
This minor planet was named by the discoverer after a common German feminine name. No special meaning is assigned to this name.[2] The official naming citation was published by the Minor Planet Center on 15 December 1968 (M.P.C. 2901).[12]
