A planetary system 897 light-years away from Earth consists of two planets that orbit a star, rotating backwards.
It used to be presumed that the equator of a spinning star needs to line up with the orbital plane of its planets due to the fact that the stars and planets are both ultimately growing from the same spinning molecular cloud.
As a result, the star needs to spin in the same direction that the planets are orbiting. However, the K2-290 system is not following this rule. Specifically, the K2-290 system comprises three stars, and it has a pair of planets that orbit the main star, identified as K2-290 A.
According to Denmark-based Aarhus University's Simon Albrecht, together with his colleagues, determined that, the rotational axis of K2-290, compared with orbits of the planets, is tilted by roughly 124 degrees.
This means that, the New Scientist reported that the star is actually spinning in approximately the opposite direction to its planets that orbit.
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Planets Orbiting a Similar Direction as the Sun is Rotating
By comparison, in the solar system, the spin axis of the sun is tilted only around six degrees compared with the planetary orbits, which means the planets are orbiting in approximately the same direction as the rotation of the sun.
Such a misalignment observed in K2-290 has been observed in the past in other planetary systems. The notion is that the turbulence during formation of the stars could lead to misalignments between a star and its planets.
Albrecht explained, whatever it is that can be produced by nature, it appears "to be produced somewhere. However, K2-290 is extraordinary in that both planets orbit in a similar plane.
This indicates that something extraordinary happened early in the history of planetary system, after the spinning molecular cloud had developed to become a star with a protoplanetary dis around it, from which the two planets were absolutely growing.
Misalignment Between a Star and Its Planets
According to the United Kingdom-based Queen's University Belfast's Chris Watson, the fact that these planets seem to be coplanar means that maybe it was not a vigorously violent mechanism that led them to migrate, probably it was the disc.
Therefore, he said, there is a need to look at "how did you end up with the star and the planet-forming disk tilted in the first planet."
Albrecht and his team believed that the entire system turned out to be misaligned due to the fact that the presence of an accompanying star, probably the K2-290 B, that could have utilized gravitational forces which moved the disc.
On the other hand, Watson said, a lot of the way they are interpreting the spin-orbit misalignment is assuming that the actual and exact planetary disc was "aligned with the whole star, in the first place."
In November last year, it was reported that, in an astronomical first, astronomers may have directly detected a star forming simultaneously as a world orbiting it, proving a long-held principle about planet formation.
Essentially, planets are believed to have formed in a disk of gas and dust earlier identified as "protoplanetary disc," that surrounds a host star.
Theoretical frameworks propose planets need to start taking shape while the host star remains growing although now, experts have only observed active evidence of the formation of planets after the star itself had gone through formation.
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