A new analysis suggests the Sun has the potential to capture interstellar objects much larger than those observed so far.
Writing in the journal Celestial Mechanics and Dynamical Astronomy, two American astrophysicists, Edward Belbruno of Yeshiva University and former NASA Chief Scientist James Green, outlined how the Sun could become a formidable “cosmic captor.”
In recent years, humanity has detected two interstellar objects: ‘Oumuamua and 2I/Borisov. While some speculative theories suggest they might have been sent by extraterrestrial civilizations, most scientists believe these objects are wanderers temporarily captured by the Sun’s gravitational influence.
Belbruno and Green developed a new model to explore the Sun’s ability to capture interstellar objects, analyzing the phase space of the solar system—a mathematical framework that describes the states of dynamic systems like our star system.
Two Types of Gravitational Capture
The researchers identified two types of gravitational capture within the solar system’s phase space:
- Weak Capture: Objects like ‘Oumuamua and 2I/Borisov likely fall into this category, where they enter a region allowing temporary, semi-stable orbits. These regions are typically located at the outer edges of gravitational boundaries.
- Permanent Capture: In this case, an object is pulled into the solar system and remains bound to the Sun indefinitely or for extraordinarily long periods.
Could the Sun Capture a Planet?
The study shows that not only small interstellar objects but even entire planets could be captured by the Sun under specific conditions.
Within a radius of 6 parsecs (~20 light-years) around the Sun, there are 131 known stars and brown dwarfs, some of which have been ejected from their own systems due to catastrophic collisions. Among them, at least six stars are predicted to pass close to the solar system within the next 50,000 years.
These stellar encounters could disturb the Oort Cloud, a vast region of icy objects surrounding the solar system. Some objects might be pushed into the inner solar system, potentially including rogue planets lingering in the vicinity.
“Phase Space Holes” and the Risk of Intrusion
The researchers also identified possible “holes” in the solar system’s phase space, which could facilitate the intrusion of interstellar objects. These holes are located approximately 3.81 light-years from the Sun, either towards or away from the galactic center.
In a worst-case scenario, the entry of an entire rogue planet into the solar system could disrupt the orbits of existing planets, potentially altering Earth’s environment and the course of life. However, such events are extremely unlikely and would only occur over exceedingly long timescales.
Implications for Future Research
This discovery enhances our understanding of the Sun’s gravitational influence and its potential to capture interstellar objects. It also provides valuable insights for observatories to identify interstellar visitors. Studying such objects could offer unprecedented opportunities to analyze materials from distant star systems, enriching our knowledge of the universe.
