_Sophia.png) Modelled shape ofSophia from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | J. Palisa |
| Discovery site | Vienna Obs. |
| Discovery date | 4 October 1885 |
| Designations | |
| (251) Sophia | |
| Pronunciation | German:[zoːˈfiːaː][2] |
Named after |
|
| A885 TA, 1907 UA 1950 RH1,1953 FN1 | |
| Orbital characteristics[4] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 134.29yr (49,050 d) |
| Aphelion | 3.4015AU |
| Perihelion | 2.8035 AU |
| 3.1025 AU | |
| Eccentricity | 0.0964 |
| 5.46 yr (1,996 d) | |
| 192.53° | |
| 0° 10m 49.44s / day | |
| Inclination | 10.511° |
| 156.02° | |
| 286.51° | |
| Physical characteristics | |
| 20.216±0.008 h[10] | |
| 9.9[1][4] | |
251 Sophia is a stonybackground asteroid from the outer regions of theasteroid belt. It was discovered on 4 October 1885, by astronomerJohann Palisa at theVienna Observatory in Austria.[1] TheS-type asteroid (S/L) has arotation period of 20.2 hours and measures approximately 28 kilometers (17 miles) in diameter. It was named after Sophia von Seeliger, wife of German astronomerHugo von Seeliger (1849–1924).[3]
Sophia is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[5][6] It orbits the Sun in theouter asteroid belt at a distance of 2.8–3.4 AU once every 5 years and 6 months (1,996 days;semi-major axis of 3.1 AU). Its orbit has aneccentricity of 0.10 and aninclination of 11° with respect to theecliptic.[4] The body'sobservation arc begins atVienna Observatory with its official discovery observation on 4 October 1885.[1]
Thisminor planet wasnamed after Sophia von Seeliger (née Stoeltzel), wife of German astronomerHugo von Seeliger (1849–1924) on the occasion of their marriage (A. Schnell). The naming likely took place in 1885, on the meeting of theAstronomische Gesellschaft in Geneva, Switzerland. Seeliger, who proposed the name to the discoverer, was later honored with asteroid892 Seeligeria, discovered by Max Wolf in 1918.[3]
In the Tholen-like taxonomy of theSmall Solar System Objects Spectroscopic Survey (S3OS2),Sophia is a common, stonyS-type asteroid, while in the survey's Bus–Binzel (SMASS) taxonomic variant, it is an Sl-subtype, which transitions from the S-type to the uncommon L-type.[6][12] In theSDSS-based taxonomy, it is anL-type asteroid[13]
In December 2000, a rotationallightcurve ofSophia was obtained fromphotometric observations by Bill Holliday in New Braunfels, Texas. Lightcurve analysis gave a well-definedrotation period of20.216±0.008 hours with a brightness variation of0.30±0.02magnitude (U=3).[10] Between 2005 and 2013, additional observations by French amateur astronomersLaurent Bernasconi, Etienne Morelle andRené Roy gave a tentative period of20.28 hours with an amplitude between 0.25 and 0.61 (U=2/2/2).[14]
Modeled lightcurves byJosef Ďurech andJosef Hanuš, using photometric data including from theLowell Photometric Database and from theWide-field Infrared Survey Explorer (WISE) were published in 2018. It gave a concurring sidereal period of20.2221±0.0002 and20.2222±0.0001 hours, respectively. Hanuš also gave twospin axes at (235.0°, −52.0°) and (47.0°, 84.0°) inecliptic coordinates (λ, β).[15][16][11]
According to the surveys carried out by theNEOWISE mission of NASA'sWISE telescope, the Infrared Astronomical SatelliteIRAS, and the JapaneseAkari satellite,Sophia measures (27.495±0.197), (28.42±4.5) and (29.65±0.42) kilometers in diameter and its surface has analbedo of (0.234±0.042), (0.2188±0.091) and (0.207±0.007), respectively.[7][8][9] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.2377 and a diameter of 28.54 kilometers based on anabsolute magnitude of 9.9.[11] Alternative mean-diameter measurements published by the WISE team include (28.201±1.301 km) and (28.804±0.212 km) with corresponding albedos of (0.244±0.047) and (0.2205±0.0481).[6][11]
