Bunburra Rockhole found in Australia
A new analysis of the Bunburra Rockhole meteorite indicates that the rock emerged from a previously unknown parent asteroid, which allows you to take a fresh look at the geology of the main body.
It is believed that the asteroid was originally large. It was divided into the core, the mantle and the crust, and the shape was rather spherical. The study of a new asteroid is an important step in understanding the process of the formation of similar objects in our system. Most of the bodies in the asteroid belt are already known, so a meteorite appeared from a destroyed object or there is another large asteroid.
Bunburra Rockhole was the first meteorite rebuilt using the Desert Fireball Network - a network of Australian cameras watching asteroids entering the atmosphere. The orbital path of the body lies within the innermost line of the asteroid belt.
Oxygen isotopes are used as an identifying footprint. It is believed that the HED group comes from West. Initially, Bunburra Rockhole was attributed to eukrites, but its composition was significantly different from HED. The new study conducted a more detailed analysis.
The results show that all the fragments have abnormal oxygen compounds, which means the initial analysis was correct. To explain the situation, brought out three options. Perhaps the rock was polluted by another material, could have come from a previously unidentified part of West, or the parent body just wasn’t fixed yet.
The main asteroid belt resides between Mars and Jupiter.
All data indicate that the third option is most likely. The chemical composition tells a lot about the history of thermal and water changes of the object. The Bunburra Rockhole is a basalt type indicating that melting happened in the original body when differentiation began.
By volume composition, Bunburra Rockhole and Vesta converge, so they could form in one part of our system.
Most likely, the parent body of Bunburra Rockhole is less than Vesta.
All large bodies in the asteroid belt and near-Earth space are classifiable. Perhaps the missing asteroid has changed due to cosmic weathering and collisions. He could be like Vesta, but inferior in size.
Interestingly, in terms of oxygen and chromium isotopes, another strange meteorite, Asuka 881394, is very similar to the object. They may have appeared at the same time and place, but they have different parent bodies.