216 Kleopatra
U–B = 0.238[4] | |
7.30[4][9][11][10][14] 7.35±0.02[5][15][17] · 7.45[13] | |
216 Kleopatra is a large
Orbit and classification
Kleopatra is a non-
Physical characteristics
Size and shape
Kleopatra is a relatively large asteroid, with a mean (volume-equivalent) diameter of 120±2 km[8][20] and an unusually elongate shape.
The initial mapping of its elongated shape was indicated by stellar occultation observations from eight distinct locations on 19 January 1991.[21] Subsequent observations with the ESO 3.6 m Telescope at La Silla, run by the European Southern Observatory, were interpreted to show a double source with two distinct lobes of similar size.[22] These results were disputed when radar observations at the Arecibo Observatory showed that the two lobes of the asteroid are connected, resembling the shape of a ham-bone. The radar observations provided a detailed shape model that appeared on the cover of Science Magazine.[18] Later models suggested that Kleopatra was more elongate and the most recent models using radar delay-Doppler imaging, adaptive optics, and stellar occultations provide dimensions of 267 × 61 × 48 km.[23][8][20]
Satellites
In 1988 a search for satellites or dust orbiting this asteroid was performed using the
Mass, density, and composition
The presence of two moons provides a way to estimate Kleopatra's mass, although its irregular shape makes the orbital modeling a challenge.[26] The most recent adaptive-optics observations and modeling provides a mass of Kleopatra of (1.49±0.16)×10−12 M⊙, or (2.97±0.32)×1018 kg, which is significantly lower than previously thought.[12] When combined with the best volume estimate for Kleopatra, this indicates a bulk density of 3.38±0.50 g/cm3.[20]
These recent bulk density results call into question the canonical view of Kleopatra as a pure metallic object.[18] Kleopatra's radar albedo suggests a high metal content in the southern hemisphere, but is similar to the more common S- and C-class asteroids along the equator.[8] One way to reconcile these observations is to hypothesize that Kleopatra is a rubble-pile asteroid with significant porosity in dynamic equilibrium.[20]
Origin
One possible origin that explains Kleopatra's shape, rotation, and moons is that it was created by an oblique impact perhaps 100 million years ago. The increased rotation would have elongated the asteroid and caused Alexhelios to split off. Cleoselene may have split off later, around 10 million years ago. Kleopatra is a
See also
References
- ^ a b c d e "216 Kleopatra". Minor Planet Center. Retrieved 22 April 2017.
- ^ "Cleopatra". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 26 January 2020.
- ISBN 978-3-540-00238-3.
- ^ a b c d e f g h "JPL Small-Body Database Browser: 216 Kleopatra" (2016-09-20 last obs.). Jet Propulsion Laboratory. Archived from the original on 23 April 2017. Retrieved 22 April 2017.
- ^ a b "LCDB Data for (216) Kleopatra". Asteroid Lightcurve Database (LCDB). Retrieved 22 April 2017.
- ^ a b "Asteroid 216 Kleopatra". Small Bodies Data Ferret. Retrieved 24 October 2019.
- ^ a b c d e P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
- ^ a b c d e f g h i Shepard et al (2018) A revised shape model of asteroid (216) Kleopatra, Icarus 311, 197-209
- ^ S2CID 46350317. Retrieved 22 April 2017.
- ^ .
- ^ Bibcode:2004PDSS...12.....T. Retrieved 22 October 2019.
- ^ S2CID 119286272.
- ^ . Retrieved 22 April 2017.
- ^ S2CID 35447010.
- ^ . Retrieved 22 April 2017.
- . Retrieved 22 April 2017.
- ISSN 0019-1035. Retrieved 22 April 2017.
- ^ PMID 10797000. Retrieved 21 March 2018.
- ^
Descamps, P. (2015). "Dumb-bell-shaped equilibrium figures for fiducial contact binary asteroids and EKBOs". Icarus. 245: 64–79. S2CID 119272485.
- ^ S2CID 237091036. Retrieved 13 October 2021.
- Bibcode:1991LPICo.765...54D. Retrieved 13 October 2021.
- ^ Marchis, F. (13 November 1999). "(216) Kleopatra". Central Bureau for Astronomical Telegrams. Retrieved 21 March 2018.
- ^
Hanuš, J.; et al. (2017). "Volumes and bulk densities of forty asteroids from ADAM shape modeling". Astronomy and Astrophysics. 601: 41. S2CID 119432730.
- Bibcode:1988LPI....19..405G. Retrieved 21 March 2018.
- ^ Marchis, Franck (2 October 2008). "Two Companions Found Near Dog-bone Asteroid". Space.com. Retrieved 20 March 2018.
- ^ S2CID 234777860. Retrieved 13 October 2021.
External links
- Lightcurve plot of 216 Kleopatra, Palmer Divide Observatory, B. D. Warner (2006)
- Triplicity and physical characteristics of Asteroid (216) Kleopatra
- Astronomers Catch Images of Giant Metal Dog Bone Asteroid – NASA article, May 2000 (archived)
- An Asteroid for the Dogs, August 2000 (archived)
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- 216 Kleopatra at AstDyS-2, Asteroids—Dynamic Site
- 216 Kleopatra at the JPL Small-Body Database