.png) A three-dimensional model of 54 Alexandra based on itslight curve | |
| 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 Gm (3.245AU) |
| Perihelion | 326.043 Gm (2.179 AU) |
| 405.763 Gm (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] |
Meandensity | 3.50±2.11 g/cm3[3] |
| 18.14h[4] | |
| 155°±4°[5] | |
| 17°±3°[5] | |
| 0.056[1][6] | |
| Tholen =C [1] SMASS =C [1] | |
| 7.66[1] | |
54 Alexandra is acarbonaceousasteroid from the intermediateasteroid belt, approximately 155 kilometers in diameter. It was discovered by German-French astronomerHermann Goldschmidt on 10 September 1858, and named after the German explorerAlexander von Humboldt; it was the first asteroid to be named after a male.[7]
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 theU.S. andMexico. As a result, asilhouette 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 mutuallyperturbing effects of other bodies, yielding an estimate of(6.16±3.50)×1018 kg.[3]
Photometric observations of this asteroid during 1990–92 gave alight curve with a period of 18.14 ± 0.04 hours and a brightness variation of 0.10 inmagnitude.[4] Alexandra has been studied byradar.[9] It was the namesake and largest member of the former Alexandraasteroid family; a dynamic group ofC-type asteroids that share similarorbital elements. Other members included70 Panopaea and145 Adeona.[10] 145 Adeona was subsequently assigned to theAdeona family, with Alexandra and Panopaea being dropped.[11]
In the Swedish filmAniara (2018) 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.
