.png) Lightcurve-based 3D-model ofBetulia | |
| Discovery[1] | |
|---|---|
| Discovered by | E. L. Johnson |
| Discovery site | Johannesburg Obs. |
| Discovery date | 22 May 1950 |
| Designations | |
| (1580) Betulia | |
| Pronunciation | /bɛˈtjuːliə/ |
Named after | Betulia Toro Herrick (wife of astronomerS. Herrick)[2] |
| 1950 KA | |
| NEO · Amor[1][3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 66.64 yr (24,342 days) |
| Aphelion | 3.2684AU |
| Perihelion | 1.1258 AU |
| 2.1971 AU | |
| Eccentricity | 0.4876 |
| 3.26yr (1,190 days) | |
| 252.41° | |
| 0° 18m 9.36s / day | |
| Inclination | 52.096° |
| 62.291° | |
| 159.50° | |
| Earth MOID | 0.1365 AU · 53.2LD |
| Physical characteristics | |
| Dimensions | 3.82 km[4] 3.9 km[5] 4.2 km(CALL-LCDB)[6] 4.57 km[7] 5.37±0.04 km[8] 5.39±0.54 km[9] 5.8 km(Gehrels 1994)[1] 8.55±5.23 km[10] |
| 6.130h[11] 6.1324±0.0002 h[12] 6.134 h[13] 6.135±0.005 h[14] 6.13836 h[9][15] 6.156 h[16] 6.48 h[17] | |
| 0.04±0.08[10] 0.05[18] 0.07±0.01[8] 0.077[7] 0.08(Gehrels 1994)[1] 0.09(CALL-LCDB)[6] 0.11[4] 0.17[5] | |
| Tholen =C[1][6] · B[19] B–V = 0.656[1] U–B = 0.249[1] | |
| 14.00[19] · 14.5[10] · 14.53[7] · 14.58[5] · 14.8[1] · 14.8±0.3[12] · 14.90[8] · 15.1[4][6] | |
1580 Betulia, provisional designation1950 KA, is an eccentric, carbonaceousasteroid, classified asnear-Earth object of theAmor group, approximately 4.2 kilometers in diameter. It was discovered on 22 May 1950, by South African astronomerErnest Johnson at theUnion Observatory in Johannesburg.[3] The asteroid was named for Betulia Toro, wife of astronomerSamuel Herrick.[2]
Betulia orbits the Sun at a distance of 1.1–3.3 AU once every 3 years and 3 months (1,190 days). Its orbit has aneccentricity of 0.49 and aninclination of 52° with respect to theecliptic.[1] The body'sobservation arc begins with its official discovery observation at Johannesburg in 1950.[3]
Betulia is anear-Earth asteroid with anEarthminimum orbital intersection distance of 0.1365 AU (20,400,000 km), which corresponds to 53.2lunar distances.[1] As anAmor asteroid, and contrary to theApollo andAten asteroids, it approaches Earth's orbit from beyond but does not cross it.Betulia is also aMars-crosser due to its eccentric orbit.[1]
In theTholen classification,Betulia is an unusualC-type asteroid, as near-Earth objects are typically of stony rather than carbonaceous composition.[1] Based on images taken by theSloan Digital Sky Survey, the asteroid has also been characterized as a carbonaceous but "brighter"B-type asteroid.[19]
Several rotationallightcurves ofBetulia were obtained from photometric observations since the 1970s. Analysis of the best-rated lightcurve gave arotation period of 6.1324 hours with a brightness variation of 0.70magnitude (U=3), indicating that the body has a non-spheroidal shape.[12] Other observations gave a period between 6.130 and 6.48 hours.[11][13][14][17]
Photometric and radiometric observations ofBetulia were also used to model the asteroid's lightcurve. It gave a concurring period of 6.13836 hours as well as a spin axis of (133.0°, 22.0°) and (136.0°, 22.0°) inecliptic coordinates (λ, β), respectively.[9][15] The results supersede previously determined rotational poles(also see LCDB summary).[6][11][16]
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer, Radar observations at theArecibo Observatory in Puerto Rico,Tom Gehrels estimate from theHazards due to Comets and Asteroids, and observations by Alan W. Harris using theNASA Infrared Telescope Facility on Mauna Kea, Hawaii,Betulia measures between 3.82 and 8.55 kilometers in diameter and its surface has analbedo between 0.04 and 0.17.[1][4][5][8][9][10][18]
TheCollaborative Asteroid Lightcurve Link takes an albedo of 0.09 and a diameter of 4.2 kilometers as best estimates and adopts anabsolute magnitude of 15.1.[6]
Thisminor planet was named after Betulia Toro Herrick, wife ofSamuel Herrick (1911–1974), an American astronomer who specialized incelestial mechanics. Herrick had studied the asteroid's orbit, and requested the name, along with that of1685 Toro.[2][20] The officialnaming citation was published by theMinor Planet Center in May 1952 (M.P.C. 768).[21]
