Based on the observations made with the James Webb space telescope of one of the best-known and closest star-forming regions to Earth, a research group from the European Space Agency (ESA) has identified dozens of rogue planets, not tied to any star, and forming double systems.
Although the existence of these planets was already known, the finding that these worlds can form pairs is surprising, since there is currently no sufficiently satisfactory explanation for this fact.
The Orion Nebula is a huge star-maternity that, in relatively recent times, has given birth to a large number of suns of all kinds, including Sun-like stars.
On the other hand, rogue planets seem to be very abundant in the universe. In fact, a study carried out by NASA and the University of Osaka in Japan suggests that these planets could even be more numerous, in our galaxy, than those that are bound to star systems.
Now, a study focused on the observations made by James Webb between September 26 and October 2, 2022 and which have totaled 34.9 hours of data capture in the area of the Orion Trapezium region, has found 540 rogue planet candidates.
In general, when astronomers classify celestial bodies that form multiple systems (composed of two or more objects bound by gravity and orbiting a common center of mass that is not a star), they conclude that the probability of existence of these systems decreases with the mass of the objects. For massive stars most are found to form pairs, while the proportion of binary systems drops to 50% for solar-type stars, and down to only 8% for brown dwarfs. In Orion, the stars have small masses.
However, among the population of 540 vagrant planets detected in Orion, 40 binary systems and two triple systems have been found, a surprisingly high result that cannot be explained by existing theoretical models.
To explain the existence of vagrant planets, astronomers resort to two scenarios. The first is based on the fragmentation and gravitational collapse of disks of material. The alternative scenario is based on the possibility that some planets, formed in stellar systems, are ejected into space due to gravitational interactions with other planets or with neighboring stars. This assumption would be plausible in the Trapezi area due to the high density of stars in the region.
However, the probability that one of these ejected planets would find a companion in similar conditions and form a linked system is minimal. Likewise, the mechanism that would make it possible for two planets to be ejected at the same time and remain bound is also not clear, as the authors point out in their study.
