4217 Engelhardt
Asteroid
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4217 Engelhardt, provisional designation 1988 BO2, is a stony Phocean asteroid and a potentially binary system from the inner regions of the asteroid belt, approximately 9 kilometers in diameter. It was discovered on 24 January 1988, by American astronomer Carolyn Shoemaker at Palomar Observatory in California, and later named after German mineralogist Wolf von Engelhardt.[12]
| Discovery[1] | |
|---|---|
| Discovered by | C. Shoemaker |
| Discovery site | Palomar Obs. |
| Discovery date | 24 January 1988 |
| Designations | |
| (4217) Engelhardt | |
Named after | Wolf von Engelhardt (German mineralogist)[2] |
| 1988 BO2 · 1944 RL 1951 RY1 · 1970 AA | |
| main-belt · Phocaea[3][4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 72.73 yr (26,563 days) |
| Aphelion | 2.8045 AU |
| Perihelion | 1.8246 AU |
| 2.3145 AU | |
| Eccentricity | 0.2117 |
| 3.52 yr (1,286 days) | |
| 272.23° | |
| 0° 16m 47.64s / day | |
| Inclination | 23.129° |
| 355.44° | |
| 348.79° | |
| Known satellites | 1 (P: 36.03 h)[5][a] |
| Physical characteristics | |
| Dimensions | 7.34±1.36 km[6] 8.742±0.356 km[7][8] 9.16±1.0 km[9] 9.24 km (derived)[3] |
| 3.066±0.001 h[10] 3.0661±0.0002 h[5][a] | |
| 0.2108±0.052[9] 0.231±0.046[7][8] 0.2489 (derived)[3] 0.37±0.17[6] | |
| S[3][11] | |
| 12.10±0.67[11] · 12.20[6] · 12.3[1][3] · 12.50[7][9] | |
Classification and orbit
Engelhardt is a stony S-type asteroid and a member of the Phocaea family (701).[4] It orbits the Sun in the inner main-belt at a distance of 1.8–2.8 AU once every 3 years and 6 months (1,286 days). Its orbit has an eccentricity of 0.21 and an inclination of 23° with respect to the ecliptic.[1]
It was first identified as 1944 RL at Turku Observatory in 1944, extending the body's observation arc by 44 years prior to its official discovery observation at Palomar.[12] It will pass about 0.0017 AU (250,000 km) from Earth threatening asteroid (29075) 1950 DA in 2736.[13]
Physical characteristics
Lightcurves
In November 2004, a rotational lightcurve of Engelhardt was obtained from photometric observations by American astronomer Brian Warner at this Palmer Divide Observatory in Colorado.[a] Lightcurve analysis gave a well-defined rotation period of 3.066 hours with a brightness amplitude of 0.16 magnitude (U=3).[10]
In December 2011, a follow-up observation by Warner gave a period of 3.0661 hours with 0.18 amplitude (U=3).[5] Due to a couple of supposed occultation and eclipsing events, Warner also suspects that Engelhardt might by a binary system with a minor-planet moon orbiting it every 36.03 hours. The result, however, is far from conclusive.[a]
Diameter and albedo
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Engelhardt measures between 7.34 and 9.16 kilometers in diameter and its surface has an albedo between and 0.231 and 0.37.[7] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.2489 and a diameter of 9.24 kilometers with on an absolute magnitude of 12.3.[3]
Naming
Baltic German geologist and mineralogist Wolf von Engelhardt (1910–2008), expert on impact craters and related mineral metamorphism. He was a professor at the University of Tübingen and a longtime director of its Institute of Mineralogy and Petrography.[2] The approved naming citation was published by the Minor Planet Center on 27 June 1991 (M.P.C. 18456).[14]
Notes
- Lightcurve plot of (4217) Engelhardt, at the Palmer Divide Observatory, by B. D. Warner (2011). The first plot gives a rotation period of 3.0661 hours. The second plot has that period subtracted and gives a possible orbital period of 36.03 hours for the presumed satellite.
