An exoplanet orbiting three stars has been discovered – for the first time in history
Only one sun can be seen in the sky on the bodies of the solar system, and in this respect, it is a bit not to be distinguished. Most Milky Way stars have at least one gravitationally bound star companion, which means that there must be quite a few two-star planets as well.
Stellar systems are often limited to a maximum of two stars, but systems have also been found in which up to seven stars are grouped together and engaged in a complex orbital dance. Scientists have just discovered a system that they believe is the first for astronomy: an exoplanet orbiting a three-star system.
To make it clearer, it is necessary to clarify – exoplanets have already been found in such three systems, but there the planet moves around only one star in the system. If the new discovery is confirmed, it turns out that this exoplanet orbits all three stars, a thing we have never seen before.
Typically, stars in the Milky Way are not born in isolation. Their birthplace is massive molecular clouds, where dense clumps of gas collapse under their own gravity.
When these clusters begin to rotate, the matter in the cloud takes the form of a disk, which gradually flows into the star in the process of formation. If this disk is split, another star or several stars will start to form in the same place. Once star formation is complete, planets are formed from the subdued matter of the disk.
Scientists estimate that 40-50 percent of stars have a pair (binary) companion, and about 20 percent are represented in systems consisting of three or more stars.
These systems have to be gravitationally quite complex, which makes the movement of small objects around them quite difficult; Nevertheless, astronomers estimate that about 2.5 percent of exoplanets must be in such a large number of systems as three or more stars.
About 32 exoplanets in the three systems have been confirmed so far. GW Orionis has now joined their ranks.
GW Orion is about 1,300 light-years from us and has caught the attention of astronomers because it is surrounded by a huge, misplaced protoplanetary disk orbiting three stars.
Using Atacama’s most powerful millimeter / submillimeter telescope (ALMA), astronomers have proven something strange about this system: There is an obvious crack in the protoplanetary disk.
According to our models of planetary formation, the reason for the existence of cracks in protoplanetary disks must have been the formation of planets. As they move around the star, such planets scatter gas and dust in an orbital path, clearing the path and leaving a fissure.
However, not everything is so clear at GW Orion. Because these three stars must generate a complex gravitational field, there is a chance that any strange characteristic in the disk will be generated by the stars themselves.
Previous analyzes have indicated that this should not have been the case; The gravitational interaction between the stars alone is not enough to fix the fissure in this disk, and therefore the exoplanet remains the probable explanation for its existence.
Under the leadership of astronomer Jeremy Smallwood, they restored a model of the GW Orion system, incorporating N-body simulation and three-dimensional hydrodynamic simulations.
It was found that, as previously suggested, the stinging force of the stars alone was not enough to eject a protoplanetary disk.
The culprit must be a Jupiter-like gas giant planet in the process of formation; Several gas giants were not ruled out either. Astronomers have not seen the exoplanet itself, which means that doubts still remain, but the agreement between two groups of researchers independent of each other points in favor of the young exoplanet.
This means that the process of formation of the planet can withstand even more extreme conditions than we thought, for example, a difficult environment such as a triple star.
“It’s really exciting because it makes the theory of planet formation so strong. “It could mean that the formation of the planet is much more active than we thought,” said Smallwood.
The team of researchers hopes that in future observations of the GW Orion system, they will also see the exoplanet or exoplanets themselves.
The research was published in the Monthly Notices of the Royal Astronomical Society.