_Wasserburg.png) Shape model ofWasserburg from itslightcurve | |
| Discovery [1] | |
|---|---|
| Discovered by | C. Shoemaker |
| Discovery site | Palomar Obs. |
| Discovery date | 5 May 1986 |
| Designations | |
| (4765) Wasserburg | |
Named after | Gerald J. Wasserburg (American geologist)[2] |
| 1986 JN1 · 1983 EA1 1986 LF | |
| main-belt(inner) [1] · Hungaria [3][4] | |
| Orbital characteristics [1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 33.15 yr (12,108 days) |
| Aphelion | 2.0621AU |
| Perihelion | 1.8289 AU |
| 1.9455 AU | |
| Eccentricity | 0.0599 |
| 2.71yr (991 days) | |
| 237.52° | |
| 0° 21m 47.52s / day | |
| Inclination | 23.710° |
| 76.546° | |
| 108.33° | |
| Knownsatellites | 1(suspected)[5][6] |
| Physical characteristics | |
| 1.777±0.485 km[7][8] 3.82 km(calculated)[4] | |
| 3.6231±0.0005h[5] 3.625±0.001 h[9] 3.62532±0.00002 h[a] 3.626±0.005 h[b] 3.6260±0.0005 h[10] 3.6280±0.0005 h[11] 3.664±0.003 h[12] 3.67±0.02 h(dated)[13] | |
| 0.4(assumed)[4] 1.000±0.087[7][8] | |
| E [4] B–V =0.852±0.043[14] V–R =0.456±0.023[14] V–I =0.813±0.040[14] | |
| 13.7[1][4] · 14.1[7] | |
4765 Wasserburg (prov. designation:1986 JN1) is a brightHungaria asteroid, suspectedbinary system andasteroid pair from the innermost regions of theasteroid belt, approximately 3 kilometers (1.9 miles) in diameter. It was discovered on 5 May 1986, by American astronomerCarolyn Shoemaker atPalomar Observatory, and later named after geologistGerald J. Wasserburg.[2][3]
Wasserburg is a bright member of theHungaria family, which form the innermost dense concentration of asteroids in theSolar System. It orbits the Sun in theinner main-belt at a distance of 1.8–2.1 AU once every 2 years and 9 months (991 days). Its orbit has aneccentricity of 0.06 and aninclination of 24° with respect to theecliptic.[1] It was first identified as1983 EA1 at Palomar in 1983, extending the body'sobservation arc by 3 years prior to its official discovery observation.[3]
Wasserburg forms an asteroid pair with(350716) 2001 XO105, and was part ofPetr Pravec's sample studyFormation of asteroid pairs by rotational fission, published in the journalNature.[4][10]
Thisminor planet was named after AmericanGerald J. Wasserburg (1927–2016), who was a professor of geology and geophysics atCaltech in California. He was a pioneer ofradiometric dating methods used inisotope geochemistry and was prominent for his accurate age determination measurements ofMoon rocks, which were instrumental for reconstructing theorigin of the Moon and for the hypothesis of theLate Heavy Bombardment.[2] Wasserburg also carried out isotopic analyses ofmeteorites, developed a time scale for theformation and evolution of the Solar System, and contributed to the theory ofnucleosynthesis.[2] Theofficial naming citation was published on 27 June 1991 (M.P.C. 18464).[15]
According to preliminary results from the survey carried out by NASA'sWide-field Infrared Survey Explorer (WISE) with its subsequentNEOWISE mission,Wasserburg measures 1.777 kilometers in diameter and its surface has an outstandingly highalbedo of 1.000,[7][8] while theCollaborative Asteroid Lightcurve Link assumes it to be anE-type asteroid, with albedo of 0.40 – derived from434 Hungaria the family's namesake and most prominent member – and calculates a larger diameter of 3.82 kilometers with anabsolute magnitude of 13.7.[4]
Between 2006 and 2014, several rotationallightcurves ofWasserburg were obtained from photometric observations by astronomersBrian Warner at his Palmer Divide Observatory (716), Petr Pravec atOndřejov Observatory, and Julian Oey at Blue Mountains Observatory (E19). Best rated lightcurve analysis gave a well-definedrotation period between 3.6231 and 3.6280 hours with a brightness variation between 0.07 and 0.60magnitude (U=3/3/3/3-).[5][9][10][11][a][b][c] Due to the changing amplitude,Wasserburg is likely one of the more elongatedly shaped primary asteroids of all known smaller binaries with an diameter of less than 10 kilometers.[5]
After being already recognized as anasteroid pair, American astronomer Brian Warner observed faint mutual eclipsing andoccultation events in April 2013. After repeated lightcurve subtraction, he was able to show thatWasserburg is likely abinary system with aminor-planet moon orbiting it every 15.97 hours. Assuming a depth of 0.03 magnitude, he estimated a secondary-to-primary mean-diameter ratio of0.16±0.02.[5] The Johnston's archive derives a diameter of280±80 meters for the satellite, based on the primary diameter given by WISE.[6] Asemi-major axis of 2.9 kilometers is also estimated for the moons orbit.[6] However, photometric observations taken in 2015, could not detect the presence of a satellite andWasserburg remains only a suspected binary.[12]
