Asteroid 511 Davida imaged by the Keck Observatory, December 2002.
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Discovery
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| Discovered by | R. S. Dugan |
| Discovery date | May 30, 1903 |
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Designations
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| Alternate name | 1903 LU |
| Minor planet category |
Main belt |
| Epoch October 22, 2004 (JD 2453300.5) | |
| Aphelion | 561.538 Gm (3.754 AU) |
| Perihelion | 385.946 Gm (2.580 AU) |
| Semi-major axis | 473.742 Gm (3.167 AU) |
| Eccentricity | 0.185 |
| Orbital period | 2058.370 d (5.64 a) |
| Average orbital speed | 16.59 km/s |
| Mean anomaly | 124.997° |
| Inclination | 15.936° |
| Longitude of ascending node | 107.683° |
| Argument of perihelion | 338.694° |
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Physical characteristics
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| Dimensions | 289±21 km (357±2 × 294±2 × 231±50)[1] |
| Mass | 4.38 × 1019 kg[2] |
| Mean density | 3.45 ± 1.51 g/cm³[2] |
| Rotation period | 0.2137235 d (5.13 h) |
| Albedo | 0.054–0.066 2 |
| Temperature | ~160 K |
| Spectral type | C |
| Apparent magnitude | 9.50[3] to 12.98 |
| Absolute magnitude (H) | 6.22 |
511 Davida (pronounced /dəˈviːdə/ də-VEE-də) is a large main belt C-type asteroid. It was discovered by R. S. Dugan in 1903. It is thought to be one of the ten most massive asteroids. It is approximately 270–310 km in diameter and comprises an estimated 1.5% of the total mass of the asteroid belt.[2][4][5] It is a C-type asteroid, which means that it is dark in colouring with a carbonate composition.
Davida is one of the few main belt asteroids whose shape has been determined by ground-based visual observation. From 2002 to 2007, astronomers at the Keck Observatory used the Keck II telescope, which is fitted with adaptive optics, to photograph Davida. The asteroid is not a dwarf planet: There are at least two promontories and at least one flat facet with 15-km deviations from a best-fit ellipsoid. The facet is presumably a 150-km global-scale crater like the ones seen on 253 Mathilde. Conrad et al. (2007) show that craters of this size "can be expected from the impactor size distribution, without likelihood of catastrophic disruption of Davida."
Davida is named after David Peck Todd, an astronomy professor at Amherst College.
Mass
In 2001, Michalak estimated Davida to have a mass of (6.64±0.56) × 1019 kg[6][7] In 2007, Baer and Chesley estimated Davida to have a mass of (5.9±0.6) × 1019 kg[8] A more recent estimate by Baer suggests Davida has a mass of 1.18 × 1019 kg.[2] This most recent estimate by Baer suggests that Davida is more massive than 704 Interamnia.[2]
External links
- Time lapse photography of Davida
- Al Conrad's research page at Keck
- Orbital simulation from JPL (Java) / Horizons Ephemeris
References
- ^ Conrad (2007). Measurements of the short axis are less precise than the other two, but also involve a discrepancy between fitting the convolved and deconvolved images (241±40 km), and fitting the edges (191±114 km).
- ^ a b c d e Baer, James (2008). "Recent Asteroid Mass Determinations". Personal Website. http://home.earthlink.net/~jimbaer1/astmass.txt. Retrieved on 2008-11-29.
- ^ "Bright Minor Planets 2003". Minor Planet Center. http://www.cfa.harvard.edu/iau/Ephemerides/Bright/2003. Retrieved on 2008-05-21.
- ^ Pitjeva, E. V. (2005). "High-Precision Ephemerides of Planets—EPM and Determination of Some Astronomical Constants" (PDF). Solar System Research 39 (3): 176. doi:. http://iau-comm4.jpl.nasa.gov/EPM2004.pdf.
- ^ "Baer Mass of 511 Davida" 0.220 / "Mass of Mbelt" 15 = 0.0146
- ^ Michalak, G. (2001). "Determination of asteroid masses (6) Hebe, (10) Hygiea, (15) Eunomia, (52) Europa, (88) Thisbe, (444) Gyptis, (511) Davida and (704) Interamnia". Astronomy & Astrophysics 374: 703-711. doi:. http://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2001/29/aa10228/aa10228.html. Retrieved on 2008-11-04.
- ^ (3.34±0.28)×10−11 solar masses, per Michalak (2001), extended dynamic model.
- ^ Baer, James; Steven R. Chesley. "Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris" (PDF). Celestial Mechanics and Dynamical Astronomy (Springer Science+Business Media B.V. 2007) 100 (2008): 27-42. doi:. http://www.springerlink.com/content/h747307j43863228/fulltext.pdf. Retrieved on 2008-11-15.: = (2.98±0.30) × 10−11*solar masses
- A.R. Conrad et al. (2007). "Direct measurement of the size, shape, and pole of 511 Davida with Keck AO in a single night", Icarus, doi:10.1016/j.icarus.2007.05.004
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