| Discovery[1] | |
|---|---|
| Discovered by | C. J. van Houten I. van Houten-G. Tom Gehrels |
| Discovery site | Palomar Obs. |
| Discovery date | 26 September 1960 |
| Designations | |
| (1778) Alfvén | |
Named after | Hannes Alfvén(physicist)[2] |
| 4506 P-L · 1936 HK 1952 DD1 · 1958 FB 1959 NN | |
| main-belt · Themis[3] | |
| Orbital characteristics[1] | |
| Epoch 31 May 2021 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 66.12 yr (24,152 days) (JPL) 113.65 yr (41,511 days) (MPC)[4] |
| Aphelion | 3.5505AU |
| Perihelion | 2.7420 AU |
| 3.1462 AU | |
| Eccentricity | 0.1285 |
| 5.58yr (2,038 days) | |
| 358.82° | |
| 0° 10m 35.4s / day | |
| Inclination | 2.4742° |
| 106.24° | |
| 136.41° | |
| Physical characteristics | |
| Dimensions | 20.51 km(calculated)[3] 20.623±0.240 km[5][6] |
| 4.8050±0.0027 h[7] 4.82±0.05h[8] | |
| 0.08(assumed)[3] 0.095±0.007[5][6] | |
| C[3] | |
| 11.59±0.15(R)[8] · 11.6[5] · 11.725±0.003(R)[7] 11.8[1][3] · 12.32±0.54[9] | |
1778 Alfvén, also designated4506 P-L, is a carbonaceous Themistianasteroid from the outer region of theasteroid belt, approximately 20 kilometers in diameter.
It was discovered on 26 September 1960, by astronomersCornelis van Houten,Ingrid van Houten-Groeneveld andTom Gehrels at the U.S.Palomar Observatory, in California.[4] It was later named after Swedish NobelistHannes Alfvén.[2]
The darkC-type asteroid is a member of theThemis family, a dynamical family of outer-belt asteroids with nearly coplanarecliptical orbits.Alfvén orbits the Sun in theouter main-belt at a distance of 2.7–3.6 AU once every 5 years and 7 months (2,038 days). Its orbit has aneccentricity of 0.13 and aninclination of 2° with respect to theecliptic.[1]
A firstprecovery was taken atLowell Observatory in 1906, extending the body'sobservation arc by 54 years prior to its official discovery observation.[4]
In February 2013, two rotationallightcurves ofAlfvén were obtained from analysis at thePalomar Transient Factory in California. The lightcurves gave arotation period of 4.82 and 4.8050 hours with a brightness variation of 0.40 and 0.36magnitude, respectively (U=3-/2).[8][7]
According to the survey carried out by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Alfvén measures 20.62 kilometers in diameter and its surface has analbedo of 0.095,[5][6] while theCollaborative Asteroid Lightcurve Link assumes an albedo of 0.08 and calculates a diameter of 20.51 kilometers with anabsolute magnitude of 11.8.[3]
Thesurvey designation "P-L" stands forPalomar–Leiden, named after Palomar Observatory andLeiden Observatory, which collaborated on the fruitfulPalomar–Leiden survey in the 1960s. Gehrels used Palomar'sSamuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped thephotographic plates to Ingrid and Cornelis van Houten at Leiden Observatory whereastrometry was carried out. The trio are credited with the discovery of several thousand minor planets.[10]
Thisminor planet was named after Swedish engineer, physicist and Nobel prize winner,Hannes Alfvén (1908–1995).[2] The officialnaming citation was published by theMinor Planet Center on 15 June 1974 (M.P.C. 3643).[11]
