Simulations reveal two families of exocomets in the Beta Pictoris system

Star system: Beta Pictoris | Distance from the Sun: 64 light years

The Beta Pictoris system is famous for its young star, two giant planets, and a large disk of dust and gas. Recent studies have found many comet-like bodies orbiting the star (exocomets). To understand how these exocomets form and evolve, researchers simulated the system with over 100,000 test particles, tracking their paths for 25 million years.

The simulations show that most material is quickly cleared out by the planets, except for two main regions: one inside the orbit of the inner planet Beta Pic c, and another between 20 and 25 astronomical units from the star. Exocomets from the inner region are shaped by gravitational resonance with Beta Pic c, leading to a narrow range of speeds, matching what is seen in observations. In contrast, exocomets from the outer region are scattered by the two giant planets, resulting in a wider range of speeds and more chaotic orbits. These two groups likely have different chemical makeups, as they spend different amounts of time close to the star where ices can vaporize.

Key findings
- Two main families of exocomets form in the simulations of Beta Pictoris system
- Inner family is shaped by resonance with Beta Pic c, producing a narrow range of velocities
- Outer family is scattered by both giant planets, leading to chaotic orbits and a wide range of velocities
- The two families likely have different volatile contents due to their different paths near the star
- Simulations match spectroscopic observations of exocomet speeds in the system

Scientific study

Exocomets of Beta Pictoris II: Two dynamical families of exocomets simulated with REBOUND (external link)