_Asplinda.png) Modelled shape ofAsplinda from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 28 September 1921 |
| Designations | |
| (958) Asplinda | |
Named after | Bror A. Asplind (Swedish astronomer)[2] |
| A921 SD · 1921 KC | |
| main-belt[1] · (outer)[3] Hilda[1][4][5] | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 97.88yr (35,751 d) |
| Aphelion | 4.7204AU |
| Perihelion | 3.2494 AU |
| 3.9849 AU | |
| Eccentricity | 0.1846 |
| 7.95 yr (2,905 d) | |
| 152.91° | |
| 0° 7m 26.04s / day | |
| Inclination | 5.6288° |
| 343.12° | |
| 92.950° | |
| Jupiter MOID | 0.7147 AU |
| TJupiter | 3.0180 |
| Physical characteristics | |
| 16.543±0.007 h[9][a] | |
| 10.4[1][3] | |
958 Asplinda (prov. designation:A921 SDor1921 KC) is a resonantHilda asteroid, approximately 47 kilometers (29 miles) in diameter, located in the outermost region of theasteroid belt. It was discovered on 28 September 1921, by astronomerKarl Reinmuth at theHeidelberg Observatory in southwest Germany.[1] The assumedC-type asteroid has arotation period of 16.5 hours and is likely elongated in shape. It was named after Swedish astronomerBror Asplind (1890–1954).[2]
Asplinda is a member of the distant orbitalHilda group of asteroids, which stay in a 3:2 orbital resonance withJupiter.[1][4][5] It is however not a member of the collisionalHilda family (001) but a non-family asteroid of thebackground population when applying thehierarchical clustering method to itsproper orbital elements.[4] It orbits the Sun in theoutermost asteroid belt at a distance of 3.2–4.7 AU once every 7 years and 11 months (2,905 days;semi-major axis of 3.98 AU). Its orbit has aneccentricity of 0.18 and aninclination of 6° with respect to theecliptic.[3] The body'sobservation arc begins at Heidelberg on 24 October 1921, four weeks after its official discovery observation.[1]
Thisminor planet was named afterBror Ansgar Asplind (1890–1954), a Swedish astronomer andorbit computer. The following, sequentially numbered asteroids959 Arne,960 Birgit and961 Gunnie are named after his three children, respectively. Thenaming was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 92).[2]
Nospectral type has been published forAsplinda. As an Hildian asteroid with a low albedo(see below) it is a carbonaceousC-type asteroid (assumed),[10] or possibly aD-type orP-type asteroid, which are very common among the Hildian and more distantJupiter trojan population.
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In December 2017, a rotationallightcurve ofAsplinda was obtained fromphotometric observations byBrian Warner,Robert Stephens and Daniel Coley at theCenter for Solar System Studies (U81) in California. Lightcurve analysis gave arotation period of16.543±0.007 hours with a high brightness amplitude of0.64±0.02magnitude, indicative of an elongated, non-spherical shape (U=3−).[9][a] The results supersedes previous observations with a period determination of17.55±0.03 h by the same astronomers in 2016, and a period of25.3 h published by Mats Dahlgren in 1998 (U=2+/2).[10]
The 2017 observations by Warner, Stephens and Coley also gave twospin axes of (228.0°, 33.0°) and (46.0°, 45.0°) inecliptic coordinates (λ, β) and a sidereal period of16.556100±0.000002 hours.
These results supersede the asteroid's 2016 modeled spin axes and lightcurve with a sidereal period of16.556100±0.000002 hours based on data from the Uppsala Asteroid Photometric Catalogue, thePalomar Transient Factory survey, and individual observers led by Czech astronomersJosef Hanuš andJosef Ďurech, as well as sparse-in-time photometry from theNOFS, theCatalina Sky Survey, and the La Palma surveys (950).[10][11]
According to the surveys carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE), the Infrared Astronomical SatelliteIRAS, and the JapaneseAkari satellite,Asplinda measures45.112±0.405,47.08±6.2 and48.57±1.51 kilometers in diameter, and its surface has analbedo of0.045±0.008,0.0415±0.013 and0.041±0.003, respectively.[6][8][7]
Another published measurement by the WISE team also gives a mean-diameters of45.117±0.091 km with corresponding albedo of0.045±0.005.[5][10] TheCollaborative Asteroid Lightcurve Link adopts the results from IRAS, that is, an albedo of 0.0415 and a diameter of 47.08 km based on anabsolute magnitude of 10.71.[10] Anasteroid occultation on 15 August 2006, gave a best-fit ellipse dimension of 47.0 × 47.0 kilometers.[5] These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is poorly rated.[5]
