First 3D Model of Exoplanet Orbiting Its Star Offers Clues on How Planets in Binary Systems Form

Astronomers have studied exoplanets for decades and have confirmed 5,084 exoplanets in 3,811 planetary systems. The discovery of each planet and system has helped them learn what is in the Universe. They used indirect methods, such as Transit Photometry and Radial Velocity Method, and other various means to find these cosmic bodies.

In the study, titled "3D Orbital Architecture of a Dwarf Binary System and Its Planetary Companion," published in The Astronomical Journal, a team of international astronomers used the Very Long Baseline Array (VLBA) network of the National Science Foundation (NSF) to detect a Jupiter-like planet orbiting the binary system GJ 896AB that is 20 light-years away from Earth and created a 3D model.

Detecting Binary Systems

The team detected the planet in a binary system using a method known as Astrometry. They detected the "wobble" that the planet makes as it orbits around the larger system's stars, Universe Today reported.

Astrometry allowed them to create the first 3D architecture of a binary system and a planet that orbits one of its stars. Researchers noted that the two stars are separated by a distance equivalent to twice the distance between Neptune and the Sun, which is approximately 30 astronomical units (AUs) and have an orbital period of 229 years.

Researcher Salvador Curiel Ramirez from the National Autonomous University of Mexico's (UNAM) Institute of Astronomy explained in a press release via the National Radio Astronomy Observatory (NRAO) that the 3D mapping could not be possible with other methods used in discovering other exoplanets.

He explained that understanding systems would help understand planet formation, especially since most stars are in binary or multiple systems. Additionally, M-type or red dwarf stars are the most common in the universe, wherein it accounts for 75% of the Milky Way alone.

ALSO READ : Exoplanet Larger Than Giant Planet Jupiter Detected Intact Under Binary System; Parent Stars Bigger and Hotter Than the Sun

3D Models Offers Insight in the Formation of Binary Star Systems

Creating the 3D model allows astronomers to interpret binary systems in which they found that the plane the planet orbits is misaligned by 148 degrees relative to the plane of the orbit of the two stars. Astronomer Gisela Ortiz-León said in the NRAO press release that this "means that the planet moves around the main star in the opposite direction to that of the secondary star around the main star."

Although binary systems are common in the universe, only 4% of known exoplanets are in binary star systems. Space.com reports that this is because it is trickier to detect planets in these systems and because previous models suggest that the existence of a companion star can destabilize a planet-forming disk.

Current models suggest that the planet-forming disk in a binary system survives for less than 1 million years before gravitational tides from its companion star accrete all their gas. The case of GJ 896AB is unique because both of its stars are red dwarfs, and it has one gas giant planet.

Scientists said that red dwarfs lack the necessary raw material to form gas giant planets, but their presence in this binary star system suggests it is possible. Additional studies on these systems will give important insights into how planets are formed in binary systems.