_Kirkwood.png) Shape model ofKirkwood from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | Indiana University (Indiana Asteroid Program) |
| Discovery site | Goethe Link Obs. |
| Discovery date | 10 January 1951 |
| Designations | |
| (1578) Kirkwood | |
Named after | Daniel Kirkwood[2] (American astronomer) |
| 1951 AT · 1944 DF 1949 TF · 1952 FK | |
| main-belt · (outer)[1] Hilda[3][4][5] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 73.37 yr (26,797 days) |
| Aphelion | 4.8617AU |
| Perihelion | 2.9855 AU |
| 3.9236 AU | |
| Eccentricity | 0.2391 |
| 7.77yr (2,839 days) | |
| 195.23° | |
| 0° 7m 36.48s / day | |
| Inclination | 0.8085° |
| 74.002° | |
| 1.7729° | |
| Jupiter MOID | 0.4366 AU |
| Physical characteristics | |
| Dimensions | 47.077±0.315 km[6] 51.88±1.8 km[4][7] 57.14±1.27 km[8] |
| 12.518±0.002h[9] 17.9±0.1 h[a] | |
| 0.044±0.002[8] 0.0517±0.004[4][7] 0.063±0.005[6] | |
| Tholen =D[1] · D[4][10] B–V = 0.788[1] U–B = 0.276[1] | |
| 10.26[1][4][7][8] · 10.41±0.50[10] | |
1578 Kirkwood, provisional designation1951 AT, is aHilda asteroid from the outermost regions of theasteroid belt, approximately 52 kilometers in diameter. It was discovered on 10 January 1951, by astronomers of theIndiana Asteroid Program atGoethe Link Observatory in Indiana, United States.[3] The asteroid was named after American astronomerDaniel Kirkwood.[2]
Kirkwood belongs to the orbitalHilda group, which is locatedoutermost part of the main belt.[4] Asteroids in this dynamical group havesemi-major axis between 3.7 and 4.2 AU and stay in a 3:2resonance with the gas giantJupiter.Kirkwood, however, is a background asteroid and not a member of the (collisional)Hilda family (101).[5]
It orbits the Sun at a distance of 3.0–4.9 AU once every 7 years and 9 months (2,839 days). Its orbit has aneccentricity of 0.24 and aninclination of 1° with respect to theecliptic.[1]
The asteroid was first observed as1944 DF atTurku Observatory in February 1944. The body'sobservation arc begins with its observation as1949 TF atHeidelberg Observatory in October 1949, fifteen months prior to its official discovery observation at Goethe Link.[3]
In theTholen classification,Kirkwood is a darkD-type asteroid.[1] It is also characterized as a D-type byPanSTARRS photometric survey.[10]
In October 2012, a rotationallightcurve ofKirkwood was obtained from photometric observations at the Etscorn Campus Observatory (719) in New Mexico, United States. Lightcurve analysis gave arotation period of 12.518 hours with a brightness variation of 0.05magnitude (U=2). Another lightcurve gave a period of 17.9 hours and an amplitude of 0.22 magnitude (U=2).[a]
According to the surveys carried out by the JapaneseAkari satellite, theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer and the Infrared Astronomical SatelliteIRAS,Kirkwood measures between 47.077 and 57.14 kilometers in diameter and its surface has analbedo between 0.044 and 0.063.[6][7][8]
TheCollaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0517 and a diameter of 51.88 kilometers based on anabsolute magnitude of 10.26.[4]
Thisminor planet was named in memory of American astronomerDaniel Kirkwood (1814–1895), long-time professor of mathematics atIndiana University. He discovered theKirkwood gaps, which are gaps in the distribution of the mean distances of the minor planets in the asteroid belt.Kirkwood was theIndiana Asteroid Program's first numbered discovery.[2][b] The officialnaming citation was published by theMinor Planet Center in March 1952 (M.P.C. 738).[11] The lunar craterKirkwood was also named in the astronomer's honor.[2]
