(ORDO NEWS) — The gas giant GJ 896Ab orbits one of the stars in a close pair of red dwarfs, while moving in the opposite direction.
Of the thousands of exoplanets known today, only a few have been found using astrometry – ultra-precise changes in the position of their parent stars.
The attraction of a sufficiently massive body orbiting a star causes it to oscillate slightly, although the deviations are so small that the method can hardly be called productive.
However, recently it was astrometry that helped not only to notice a new exoplanet, but also for the first time to determine the three-dimensional structure of its orbit.
Scientists from Mexico, Germany and the United States observed the binary system GJ 896AB, which is only 20 light years away.
It includes a pair of small and dim red dwarfs with a mass of 44 and 17 percent of the mass of the Sun.
They are separated by approximately the same distance as Neptune – from the Sun, a complete revolution around the center of the star is done in 229 Earth years.
For a new study of the system, astronomers used an array of radio telescopes VLBA, as well as archival observational data in the optical range.
Weak fluctuations in the movement of the larger star of this tandem showed that an exoplanet was orbiting around it.
Scientists have calculated that this gas giant is 2.3 times heavier than Jupiter, making an annual revolution in 284 of our days.
The orbit of GJ 896Ab is slightly smaller than that of Venus, and thanks to the VLBA it was possible to determine it in all three dimensions.
It turned out that the plane of the orbit of this exoplanet is inclined by 148 degrees relative to the orbit of the binary system itself: in fact, it moves around its star in the opposite direction relative to the “younger” star rotating further. There is nothing like it in the solar system.
The authors of the work note that red dwarfs are the most common type of stars in the Galaxy, most of them are in binary systems.
Therefore, our knowledge of them is in its own way even more significant than anything that can be found out within the solar system.
They allow clarifying the existing ideas about the formation and evolution of most planets, which clearly need to be clarified.
“In particular, models predict that such a large planet is unlikely to be a neighbor of such a small star.
So, perhaps these models should be reconsidered,” summed up (Joel Sanchez-Bermudez), one of the authors of the study.
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