A planet that could resemble a smaller version of our own Neptune has been discovered orbiting one of two Sun-like stars that also orbit each other.
The planet, named TOI 4633 cy and detected by transiting in front of its star through NASA’s TESS (Transiting Exoplanet Survey Satellite) mission, completes an orbit every 272 days in the habitable zone, the distance of a star that could allow it to be form liquid water on a planetary surface.
But that is almost certainly not the case; It most likely has a large, dense atmosphere, perhaps similar to that of Neptune, which would exclude the existence of surface water, according to NASA.
On the other hand, measurements made with a second detection method revealed a possible sister planet with a 34-day orbit. This one, from Earth’s perspective, does not cross the face of its star, so its potential presence was revealed by “radial velocity.” Light from a star shifts slightly back and forth as the gravity of an orbiting planet pulls it in one direction and then another; Follow-up investigations will be needed to confirm that the sister planet, suggested by radial velocity measurements, is really there.
Further investigation of this system could also prove important for understanding binary star systems, or pairs of stars that orbit each other. In this case, a companion star orbits the primary star in just 230 years, allowing them to get closer to each other by interstellar standards.
The stars’ mutual oval-shaped orbit and close approach, along with a transiting planet in a long orbit around one of the stars, make this a standout system, one that will allow scientists to test their ideas about how form planetary systems and whether such unusual orbital configurations can manage to remain stable for billions of years.
The findings have been published in The Astronomical Journal by an international team led by astrophysicist Nora L. Eisner of the Flatiron Institute in New York.
