.png) Lightcurve-based 3D-model ofOort | |
| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth I. Groeneveld |
| Discovery site | Heidelberg Obs. |
| Discovery date | 9 September 1956 |
| Designations | |
| (1691) Oort | |
Named after | Jan Oort(astronomer)[2] |
| 1956 RB · 1945 TD 1947 DA · 1950 PZ 1950 RU · 1951 XW 1955 MW · 1956 SD 1964 DA · A917 TD | |
| main-belt · Themis[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 71.42 yr (26,086 days) |
| Aphelion | 3.7153AU |
| Perihelion | 2.6084 AU |
| 3.1618 AU | |
| Eccentricity | 0.1750 |
| 5.62yr (2,054 days) | |
| 240.25° | |
| Inclination | 1.0860° |
| 174.55° | |
| 232.69° | |
| Physical characteristics | |
| Dimensions | 27.13 km(calculated)[3] 33.163±0.534 km[4] 33.644±0.267[5] 37.37±0.74 km[6] |
| 10.2684±0.0005h[7] 10.2705±0.0004 h[8] | |
| 0.053±0.002[6] 0.065±0.011[5] 0.0672±0.0150[4] 0.10(assumed)[3] | |
| Tholen = CU[1] · CU[3] B–V = 0.682[1] U–B = 0.316[1] | |
| 10.90±0.12[9] · 10.95[1][3][4][6] | |
1691 Oort, provisional designation1956 RB, is a rare-typecarbonaceousThemistianasteroid from the outer region of theasteroid belt, approximately 33 kilometers in diameter.
It was discovered on 9 September 1956, by German astronomerKarl Reinmuth and Dutch astronomerIngrid van Houten-Groeneveld atHeidelberg Observatory in south-west Germany.[10] It was later named after Dutch astronomerJan Oort.[2]
is a member of theThemis family, a dynamical family of outer-belt asteroids with nearly coplanarecliptical orbits.Oort orbits the Sun at a distance of 2.6–3.7 AU once every 5 years and 7 months (2,054 days). Its orbit has aneccentricity of 0.18 and aninclination of 1° with respect to theecliptic.[1]
It was first identified as1945 TD atTurku in 1945, extending body'sobservation arc by 14 years prior to its official discovery observation. Information about an earlier 1917-identification,A917 TD, is not available.[10]
The darkC-type asteroid, classified as a rare intermediate CU-type in theTholen taxonomy.[1]
In February 2009, a rotationallightcurve ofOort was obtained from photometric observations taken by French amateur astronomerRené Roy. It gave a well-definedrotation period of 10.2705 hours with a brightness variation of 0.38magnitude (U=3).[8] An international study from 2013, published a concurring, modeled period of 10.2684 hours (n.a.).[7]
According to the surveys carried out by the JapaneseAkari satellite and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Oort measures 33.64 and 37.37 kilometers in diameter, and its surface has analbedo of 0.065 and 0.053, respectively.[4][5][6] TheCollaborative Asteroid Lightcurve Link assumes an albedo of 0.10 and calculates a diameter of 27.13 kilometers with anabsolute magnitude of 10.95.[3]
Thisminor planet was named in honor of Dutch astronomerJan Oort (1900–1992), director of theLeiden Observatory (1945–1970), president of theInternational Astronomical Union (1958–1961), and a well-known authority on stellar statistics and galactic structure.[2]
He overturned the idea that the Sun was at the center of the Milky Way. TheOort cloud, the outermost gravitationally bound region of the Solar System, was also named after him. The officialnaming citation was published by theMinor Planet Center on 15 February 1970 (M.P.C. 3023).[11]
