Jocelyne LeBlanc September 12, 2021
New photos taken of the incredibly unique Kleopatra asteroid that is shaped like a dog bone have revealed very interesting details. Kleopatra is located in the Asteroid Belt that’s located between Mars and Jupiter. It has two lobe shapes on either end with a long “neck” in between them – basically it looks like a dog bone. Additionally, it has two tiny moons that have been named AlexHelios and CleoSelene after the Egyptian Pharaoh Cleopatra’s kids.
Even though Kleopatra was discovered back in 1880, scientists have only known about its size as well as the moons for approximately twenty years, but the new photos showing different angles have helped them even more, like calculating the its measurements, the moons’ orbits, and how they were formed. They did this with observations from the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in Chile.
They concluded that Kleopatra measures about 270 kilometers in length (168 miles); that one of the lobe shapes is larger than the other; and that its “neck” is actually quite thick. A different team of researchers then calculated the orbits of the two moons in order to figure out the mass of the asteroid. They determined that Kleopatra’s mass is 2.97 x 1018 kilograms which is quite a bit less than previous estimates that had it at 4.64 x 1018 kilograms.
The researchers were then able to calculate the density and based on the assumption that the asteroid is rich in metals, the number was rather low. Since Kleopatra has low density, it would indicate that it is quite porous with a lot of loose rock that is hardly secure on the asteroid. This also suggests that the “rubble pile” may have happened when a bunch of debris was thrown off of a parent body when a large impact occurred. Furthermore, if there is material that is being ejected from the asteroid, that could explain how the two moons were formed.
Unfortunately for Kleopatra, its very fast rotation could make it fall apart pretty easily if it is porous. In fact, it rotates once every 5.4 hours and if it were to pick up even a slight amount of speed, it would tear apart.
But for now, it is quickly rotating through space and the new images have certainly helped with learning more about this very odd-looking “dog bone” asteroid. Astronomer Franck Marchis from the SETI Institute and the Laboratoire d’Astrophysique de Marseille in France said it best when he stated, “Kleopatra is truly a unique body in our Solar System.” More pictures of the Kleopatra asteroid can be seen here.
Two studies about the asteroid have been published in Astronomy & Astrophysics and they can be read here https://www.aanda.org/articles/aa/full_html/2021/09/aa40874-21/aa40874-21.html and here https://www.aanda.org/articles/aa/full_html/2021/09/aa40901-21/aa40901-21.html