54 Alexandra
Main-belt asteroid
From Wikipedia, the free encyclopedia
54 Alexandra is a carbonaceous asteroid from the intermediate asteroid belt, approximately 155 kilometers in diameter. It was discovered by German-French astronomer Hermann Goldschmidt on 10 September 1858, and named after the German explorer Alexander von Humboldt; it was the first asteroid to be named after a male.[7]
A three-dimensional model of 54 Alexandra based on its light curve (top) and images of the asteroid (bottom) | |
| Discovery[1] | |
|---|---|
| Discovered by | H. Goldschmidt |
| Discovery date | 10 September 1858 |
| Designations | |
| (54) Alexandra | |
| Pronunciation | /ˌælɪɡˈzændrə, -ˈzɑːn-/ AL-ig-ZA(H)N-drə[2] |
Named after | Alexander von Humboldt (German explorer) |
| Main belt | |
| Adjectives | Alexandrian |
| Orbital characteristics | |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 485.483 million km (3.245 AU) |
| Perihelion | 326.043 million km (2.179 AU) |
| 405.763 million km (2.712 AU) | |
| Eccentricity | 0.196 |
| 1,631.620 d (4.47 a) | |
| 103.809° | |
| Inclination | 11.804° |
| 313.446° | |
| 345.594° | |
| Physical characteristics | |
| Dimensions | 160 × 135 km (± 1 km) |
| 154.137 km[1] | |
| Mass | (6.16±3.50)×1018 kg[3] |
Mean density | 3.50±2.11 g/cm3[3] |
| 18.14 h[4] | |
Pole ecliptic longitude | 17°±3°[5] |
Pole ecliptic latitude | 155°±4°[5] |
| 0.056[1][6] | |
| Tholen = C[1] SMASS = C[1] | |
| 7.66[1] | |
Description
On May 17, 2005, this asteroid occulted a faint star (magnitude 8.5) and the event was observed and timed in a number of locations within the U.S. and Mexico. As a result, a silhouette profile was produced, yielding a roughly oval cross-section with dimensions of 160 × 135 km (± 1 km).[8] The mass of the asteroid can be estimated based upon the mutually perturbing effects of other bodies, yielding an estimate of (6.16±3.50)×1018 kg.[3]
Photometric observations of this asteroid during 1990–92 gave a light curve with a period of 18.14 ± 0.04 hours and a brightness variation of 0.10 in magnitude.[4] Alexandra has been studied by radar.[9] It was the namesake and largest member of the former Alexandra asteroid family; a dynamic group of C-type asteroids that share similar orbital elements. Other members included 70 Panopaea and 145 Adeona.[10] 145 Adeona was subsequently assigned to the Adeona family, with Alexandra and Panopaea being dropped.[11]
In popular culture
In the Swedish film Aniara, it is mentioned that 54 Alexandra is the closest celestial body which the off-course and out-of-control spacecraft will approach before it leaves the Solar System.
