_Sillanp%25C3%25A4%25C3%25A4.png) Shape ofSillanpää modelled from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | Y. Väisälä |
| Discovery site | Turku Obs. |
| Discovery date | 26 January 1938 |
| Designations | |
| (1446) Sillanpaa | |
Named after | Frans Sillanpää(writer)[2] |
| 1938 BA · 1935 GB 1952 HQ3 · 1955 DQ 1965 EA | |
| main-belt · Flora[3] | |
| Orbital characteristics[1] | |
| Epoch 16 February 2017 (JD 2457800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 78.53 yr (28,683 days) |
| Aphelion | 2.4732AU |
| Perihelion | 2.0179 AU |
| 2.2455 AU | |
| Eccentricity | 0.1014 |
| 3.37yr (1,229 days) | |
| 98.112° | |
| 0° 17m 34.44s / day | |
| Inclination | 5.2572° |
| 17.549° | |
| 196.25° | |
| Physical characteristics | |
| Dimensions | 7.35±0.29 km[4] 8.167±0.154 km[5] 8.19 km(calculated)[3] 8.763±0.063 km[6] |
| 9.65855±0.00005h[7] 9.659±0.001 h[8] 9.6597±0.0172 h[9] 9.6602±0.0008 h[a] | |
| 0.2109±0.0108[6] 0.24(assumed)[3] 0.241±0.046[5] 0.327±0.080[4] | |
| S[3] | |
| 12.394±0.002(R)[9] · 12.50[4] · 12.6[1][3][6] | |
1446 Sillanpää, provisional designation1938 BA, is a stony Florianasteroid from the inner regions of theasteroid belt, approximately 8.2 kilometers in diameter. It was discovered on 26 January 1938, by Finnish astronomerYrjö Väisälä atTurku Observatory in Southwest Finland.[10] It was later named after writerFrans Eemil Sillanpää.[2]
TheS-type asteroid is a member of theFlora family, one of the largest populations of stony asteroids in the main-belt. It orbits the Sun at a distance of 2.0–2.5 AU once every 3 years and 4 months (1,229 days). Its orbit has aneccentricity of 0.10 and aninclination of 5° with respect to theecliptic.[1]Sillanpää was first identified as1935 GB atSimeiz Observatory in 1935, while itsobservation arc begins with its official discovery observation at Turku in 1938.[10]
In March 2009, Czech astronomerPetr Pravec obtained a rotationallight-curve from photometric observations atOndřejov Observatory.[b] It gave a well-definedrotation period of 9.6602 hours with a brightness variation of 0.55magnitude (U=3).[a] One month later, a concurring period of 9.659 hours with an amplitude of 0.71 magnitude was obtained byAdrián Galád atModra Observatory (U=3).[8] Photometric observations at thePalomar Transient Factory in December 2011. gave a 9.6597 hours and Δ0.59 in magnitude (U=2).[9] A modeled light-curve using data from theUppsala Asteroid Photometric Catalogue and other data sources, gave a period of 9.65855 hours, as well as a spin axis of (129.0°, 76.0°) inecliptic coordinates (U=n.a.).[7]
According to the survey carried out by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Sillanpää measures between 7.35 and 8.76 kilometers in diameter, and its surface has analbedo between 0.21 and 0.327.[5][6][4] TheCollaborative Asteroid Lightcurve Link assumes an intermediate albedo of 0.24 – derived from8 Flora, the largest member and namesake of this asteroid family – and calculates a larger diameter of 8.19 kilometers using anabsolute magnitude of 12.6.[3]
Thisminor planet was named after one of the most famous Finnish writers,Frans Eemil Sillanpää (1888–1964), first Finnish writer to receive theNobel Prize in Literature in 1939(also seeList of Laureates since 1901).[2] The officialnaming citation was published by theMinor Planet Center on 20 February 1976 (M.P.C. 3928).[11]
