Low-albedo asteroids preserve a record of the solar system’s original planetesimals and the conditions in which the solar nebula was active. However, the origin and evolution of these asteroids need to be more contained.

In a new study, an international research team, including geoscientists from Heidelberg University, has successfully measured a hitherto unknown class of asteroids. The infrared range measurements could lead to the identification of a hitherto unknown class of asteroids.

Like the dwarf planet Ceres, they are rich in water and are located in the asteroid belt between Mars and Jupiter. Computer simulations suggest that complicated dynamical processes moved these asteroids from the outer solar system to the current asteroid belt shortly after their formation.

The dwarf planet Ceres is the largest asteroid between Mars and Jupiter, with an equatorial diameter of about 900 kilometers. This area is also home to many other minor planets.

prof. Dr. Mario Trieloff of the Institute of Earth Sciences at Heidelberg University said: “These are the remains of the building materials from which the planets of our solar system formed four and a half billion years ago. In these small bodies and their fragments, the meteorites, we find numerous remains that point directly to the process of planet formation.”

“The current study shows that the small astronomical bodies originated from all regions of the early solar system. Through small bodies from the outer solar system, water could have reached the still-growing Earth in the form of asteroids, because the building blocks of the planets in the inner solar system tended to be dry.”

Dr. Driss Takir of the NASA Infrared Telescope facility at the Mauna Kea Observatory in Hawaii, USA, said: “The astronomical measurements allow the identification of Ceres-like asteroids as small as 100 kilometers in diameter, currently located in a restricted region between Mars and Jupiter near Ceres’ orbit.”

“At the same time, the infrared spectra support conclusions about the chemical and mineralogical composition of the bodies. Like Ceres, there are minerals on the surface of the discovered asteroids that were created by interaction with liquid water.”

Dr. Wladimir Neumann, a member of Prof. Trieloff’s team, said: “Shortly after the formation of the asteroids, temperatures were not high enough to convert them into a compact rock structure; they retained the porous and primitive character typical of the outer ice planets far from the sun.”

These Ceres-like objects may have first formed in a cold region at the edge of our solar system, depending on the objects’ characteristics and their location in a relatively small region of the outer asteroid belt.

Gravitational perturbations altered the trajectories of these asteroids into the orbits of massive planets such as Jupiter and Saturn, otherwise known as “giant planetary instability,” causing the asteroids to become “implanted” in today’s asteroid belt. The scientists’ computer estimates of orbital developments in the early solar system were used to illustrate this.

Magazine reference:

  1. Takir, D., Neumann, W., Raymond, S. N. et al. Late accretion of Ceres-like asteroids and their implantation in the outer main belt. Wet Astron (2023). DOI: 10.1038/s41550-023-01898-x