|Discovered by||H. Goldschmidt|
|Discovery date||27 June 1857|
|Epoch November 26, 2005 (JD 2453701.5)|
|Aphelion||440.305 Gm (2.943 AU)|
|Perihelion||373.488 Gm (2.497 AU)|
|406.897 Gm (2.720 AU)|
|1638.462 d (4.49 a)|
Average orbital speed
S/2004 (45) 1
|Dimensions||305×220×145 km |
|107.3 ± 2.1 km |
|Mass||5.8 ± 0.2 ×1018 kg |
|1.1 ± 0.3 g/cm³ |
Equatorial surface gravity
Equatorial escape velocity
Sidereal rotation period
|0.2375 d (5.699 h) |
|117 ± 10°|
Pole ecliptic latitude
|-30 ± 10°|
Pole ecliptic longitude
|124 ± 10°|
|0.040 ± 0.002 |
Discovery[change | change source]
Eugenia was found in 1857 by Hermann Goldschmidt. It was named after Empress Eugenia di Montijo, the wife of Napoleon III, and was the first asteroid to be named after a real person, rather than a figure from classical legend (although there had been controversy about whether 12 Victoria was really named for the mythological figure or for Queen Victoria).
Physical characteristics[change | change source]
Eugenia is a big asteroid, with a diameter of 214 km. It is an F-type asteroid, which means that it is very dark in colouring (darker than soot) made up of carbonate. Like Mathilde, its density appears to be unusually low, indicating that it may be a loosely-packed rubble pile (an asteroid that has been broken apart by a collision and pulled back together by gravity).
Lightcurve analysis indicates that Eugenia's pole most likely points towards ecliptic coordinates (β, λ) = (-30°, 124°) with a 10° uncertainty, which gives it an axial tilt of 117°. Eugenia's rotation is then retrograde.
Moons[change | change source]
In November 1998, astronomers at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, found a small moon orbiting Eugenia. This was the first time a moon orbiting an asteroid had been found by a ground-based telescope. Eugenia's moon has been named (45) Eugenia I Petit-Prince, after Empress Eugenia's son, the Prince Imperial. The moon is much smaller than Eugenia, about 13 km in diameter, and takes five days to complete an orbit around it.
A second, smaller (estimated diameter of 6 km) moon that orbits closer to Eugenia than Petit-Prince has since been found and provisionally named S/2004 (45) 1. It was found by analyses of three images acquired in February 2004 from the 8.2 m VLT "Yepun" at the European Southern Observatory (ESO) Cerro Paranal, in Chile. The discovery was announced in IAUC 8817, on 7 March 2007 by Franck Marchis and his IMCCE collaborators.
Other websites[change | change source]
- Johnston Archive data
- Astronomical Picture of Day 14 October 1999
- SwRI Press Release
- Orbit of Petit-Prince, companion of Eugenia
- IAUC 8177
- Shape model derived from lightcurve (on page 17)
References[change | change source]
- Discovery Circumstances: Numbered Minor Planets, Minor Planet Centre Archived 20 June 2007 at WebCite
- ASTORB orbital elements database, Lowell Observatory
- Supplemental IRAS Minor Planet Survey Archived 17 January 2010 at WebCite
- M. Kaasalainen; et al. (2002). "Models of Twenty Asteroids from Photometric Data" (PDF). Icarus. 159: 369.
- synthesis of several observations, F. Marchis. Archived 17 January 2010 at WebCite
- F. Marchis; et al. (2004). "Fine Analysis of 121 Hermione, 45 Eugenia, and 90 Antiope Binary Asteroid Systems With AO Observations". Bulletin of the American Astronomical Society. 36: 1180.
- Uncertainty calculated from uncertainties in the orbit of Petit-Prince.
- On the extremities of the long axis.
- PDS lightcurve data Archived 17 January 2010 at WebCite
- Supplemental IRAS minor planet survey Archived 17 January 2010 at WebCite
- PDS node taxonomy database Archived 16 January 2010 at WebCite
- http://adsabs.harvard.edu/abs/2007IAUC.8817....1M IAUC 8817 Archived 25 June 2007 at WebCite
- IMCCÉ Breaking News Archived 20 March 2012 at WebCite