Researchers have made significant strides in uncovering the mystery of asteroids with moons, thanks to insights from the Gaia mission. Utilizing data from Gaia’s third data release, scientists have identified 3,038 binary asteroid candidates, shedding light on a previously unexplored population of celestial pairs consisting of an asteroid and a smaller moonlet. This groundbreaking discovery showcases the potential for new findings in the realm of small and intermediate-sized objects within our solar system.
The Gaia spacecraft, launched by the European Space Agency (ESA) in 2013, has played a pivotal role in revolutionizing astronomy. By providing precise measurements of the positions, distances, and motions of over a billion stars in the Milky Way, Gaia has offered unprecedented insights into the cosmos. In addition to stars, Gaia has also observed thousands of asteroids in our solar system, allowing astronomers to track their movements with exceptional accuracy.
Binary asteroids, characterized by two asteroids gravitationally bound to each other, offer a unique window into the collisional and dynamic processes that have shaped our solar system. These systems typically feature a larger primary body with a smaller moonlet orbiting around it. Despite their significance, binary asteroids have proven challenging to detect due to their small size and distance from Earth. While astronomers anticipated that nearly one-sixth of asteroids would have a companion, only 500 out of the million known asteroids have been identified as part of binary systems.
Lead author of the new study, Luana Liberato of Observatoire de la Côte d’Azur in France, highlights the potential for many more asteroid moons to be discovered, emphasizing the vast opportunities for further exploration in this area. The identification of 3,038 binary asteroid candidates through the Gaia mission signals a major breakthrough in our understanding of these celestial bodies.
Before the era of the Gaia mission, the discovery of binary asteroids relied on various techniques, each with its own limitations. High-resolution imaging from ground-based or space telescopes could detect widely separated asteroid companions, while photometry was effective in identifying variations in the light curve of asteroids with compact systems. Radar ranging also provided valuable data on near-Earth asteroids. However, these methods were constrained by factors such as asteroid size, separation between components, and brightness, underscoring the need for a more comprehensive approach.
Astrometry, the precise measurement of the positions and motions of celestial objects, emerged as a powerful tool in identifying binary asteroids. By detecting periodic variations in an asteroid’s position that indicate the presence of a companion, researchers developed a sophisticated method to uncover these elusive systems. This approach, which leverages Gaia’s astrometric data, filters out noise and spurious signals to pinpoint promising binary candidates.
Applying this method to a sample of 30,030 asteroids observed by Gaia, researchers identified 3,038 binary asteroid candidates, surpassing the current population of known binary asteroids. The success of this approach underscores the significant impact of Gaia’s data on advancing our knowledge of asteroids and their moons.
Timo Prusti, Project Scientist for Gaia at ESA, commends the mission for its outstanding contributions to asteroid exploration, emphasizing the continuous advancements in data quality with each release. The findings from the study not only highlight Gaia’s role in unlocking new scientific discoveries but also prompt further investigation into the formation mechanisms of binary asteroids.
The prevalence of binary systems among small and intermediate asteroids challenges existing theories on their origins, suggesting alternative formation scenarios such as rotational fission or gravitational interactions within asteroid families. To unravel this mystery, additional research is essential, with the European Space Agency’s upcoming Hera mission poised to delve deeper into the dynamics of binary asteroids. Hera’s mission, following NASA’s DART mission, aims to investigate the impact of a collision with a moonlet orbiting an asteroid, offering valuable insights into these complex systems.
As the study “Binary asteroid candidates in Gaia DR3 astrometry” is published in Astronomy & Astrophysics, the scientific community looks forward to further discoveries and revelations from ongoing missions and research efforts. The Gaia mission continues to push the boundaries of our understanding of the solar system and beyond, paving the way for groundbreaking insights into the mysteries of asteroids with moons.
