511_Davida

511 Davida

511 Davida

Large asteroid in the asteroid belt

Davida (minor planet designation: 511 Davida) is a large C-type asteroid. It is one of the largest asteroids; approximately tied for 7th place, to within measurement uncertainties, and the 5th or 6th most massive. It was discovered by R. S. Dugan in 1903. Davida is named after David Peck Todd, an astronomy professor at Amherst College.

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Physical characteristics

Asteroid 511 Davida (lower left at mag 12.5) near galaxy NGC 5792
3D model of Davida based on lightcurve modeling
Keck telescope image sequence of Davida showing its rotation

Davida is approximately 270–310 km in diameter and comprises an estimated 1.5% of the total mass of the asteroid belt.[9][10][lower-alpha 4] It is a C-type asteroid, which means that it is dark in colouring with a carbonaceous chondrite composition.

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."

Mass

In 2001, Michalak estimated Davida to have a mass of (6.64±0.56)×1019 kg.[11][lower-alpha 5] In 2007, Baer and Chesley estimated Davida to have a mass of (5.9±0.6)×1019 kg.[12] As of 2010, Baer suggests Davida has a mass of (3.84±0.20)×1019 kg.[9] This most recent estimate by Baer indicates that Davida is approximately tied with 704 Interamnia as the fifth-most-massive asteroid, though the error bars of Interamnia are large.[9]

Occultations

There have been 9 occultation events observed since 1987, many of which produced two or three chords.[13] Two examples shown here.

Occultations by 511 Davida: Left: Double chord occultation of TYC 5597-01223 on 5 August 2016, observed by two amateur astronomers in eastern Australia. Both observers noted step events, thereby detecting the star has two components. Right: Triple chord occultation of TYC 1964-00787, observed on 6 February 2009 by three astronomers in eastern United States.
511 Davida occulted TYC 5597-01223 on 5 August 2016. Two observers recorded the event and both observed step events. Shown here is the step recording by Dave Herald.

Notes

  1. 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).
  2. Flattening derived from the maximum aspect ratio (c/a): , where (c/a) = 0.70±0.06.[7]
  3. (18.96 ± 0.99) × 10−12 M☉
  4. "Baer Mass of 511 Davida" 0.220 / "Mass of Mbelt" 15 = 0.0146
  5. (3.34±0.28)×10−11 solar masses, per Michalak (2001), extended dynamic model.

References

  1. [1]
    John Daintith & William Gould, eds. (2006) The Facts On File Dictionary of Astronomy. 5th edition. Infobase Publishing.
  2. [2]
    "Asteroid 511 Davida – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved October 24, 2019.
  3. [3]
    "Davidian". Merriam-Webster.com Dictionary.
  4. [4]
    JPL data Retrieved 2021-09-29
  5. [5]
    James Baer, Steven Chesley & Robert Matson (2011) "Astrometric masses of 26 asteroids and observations on asteroid porosity." The Astronomical Journal, Volume 141, Number 5
  6. [6]
    Conrad (2007), as cited in Baer et al. (2011).[5]
  7. [7]
    P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
  8. [8]
    "Bright Minor Planets 2003". Minor Planet Center. Retrieved May 21, 2008.[permanent dead link]
  9. [9]
    Baer, James (2010). "Recent Asteroid Mass Determinations". Personal Website. Archived from the original on July 2, 2013. Retrieved February 13, 2011.
  10. [10]
    Pitjeva, E. V. (2005). "High-Precision Ephemerides of Planets—EPM and Determination of Some Astronomical Constants" (PDF). Solar System Research. 39 (3): 176. Bibcode:2005SoSyR..39..176P. doi:10.1007/s11208-005-0033-2. Archived from the original (PDF) on October 31, 2008.
  11. [11]
    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. Bibcode:2001A&A...374..703M. doi:10.1051/0004-6361:20010731. Archived from the original on December 4, 2012. Retrieved November 4, 2008.
  12. [12]
    Baer, James; Steven R. Chesley (2007). "Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris". Celestial Mechanics and Dynamical Astronomy. 100 (2008). Springer Science+Business Media B.V. 2007: 27–42. Bibcode:2008CeMDA.100...27B. doi:10.1007/s10569-007-9103-8. (2.98±0.30)×10−11 solar masses
  13. [13]
    "PDS Asteroid/Dust Subnode". sbn.psi.edu. Archived from the original on April 25, 2018. Retrieved April 27, 2018.
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