Astrophysicists have found that the presence of a planet of the right size orbiting its mother fast enough appears to slow the star’s aging process.
Specifically, a gas giant in close orbit could transfer angular momentum to the star’s rotation, counteracting the gradual loss of rotation caused by the braking effect of the star’s magnetic field.
It is somewhat difficult to study the influence of exoplanets on the rotation of their host stars. And if you are looking at a star and a planet, you have no way of knowing if the speed of rotation has affected the planet.
However, many stars in the universe are found in multi-star systems, and binary stars are generally stellar twins, born in the same nebula, of the same mass of dust and gas.
As such, their properties are often very similar and have the same color, size, brightness and, yes, rotation, according to the study cited by Science Alert, citing the Royal Astronomical Society’s Monthly Notice.
Therefore, to closely examine the influence of planets on the rotation and activity of stars, a team of astronomers led by Nicoletta Elick of the Leibniz Institute for Astrophysics in Potsdam (AIP) in Germany conducted the equivalent of a study in double star.
They looked for binary star systems where a star has exoplanets in its orbit and there aren’t any. They then used the planetless star as a control to look for changes that could occur from the planet orbiting the other star.
But a single star system would not be enough to create a model; In their study, the team closely examined 34 couples.
“In medicine, you need a lot of patients enrolled in a study to see if the effects are real or a little weird,” Elick says. … The same may be true in astronomy, and this study gives us the certainty that these hot Jupiters do. The stars that revolve around it are smaller than they actually are. “
Hot Jupiters are strange spheres … They are gas giants, like Jupiter, but they are incredibly close to their host stars – with orbital periods of days or even hours. And in this proximity they are warmed by the star, which earns them the nickname.
Elek and his colleagues studied X-ray data on 34 binary systems, acquired by NASA’s Chandra Observatory. And because faster-spinning stars exhibit greater X-ray activity than slower spinning stars, they were able to find a distinct spin speed difference between the two stars in their binary pairs.
Actually, the fastest stars were those with hot Jupiters; The giants orbiting farther from their star have had no observable effects.
As the rotation of stars gradually slows down over time, younger stars tend to rotate faster than older stars with similar characteristics. This suggests that hot Jupiters are like the wrinkled cream of the stars. The interaction between the star and the exoplanet results in a transfer of rotation from an exoplanet to the star which improves the rotation of the latter.
The exact details of this interaction are currently somewhat of a mystery. The researchers speculated, or for their analysis, that the tides depend on the gravity between the two objects, but magnetic forces could play a role and further investigations could help to know the finer details.
“In the previous cases there were some very interesting suggestions, but now we have statistical evidence that some planets really affect their stars and make them act young,” says AIP astronomer Marzia Hosseini. they’ll help reveal more ways to better understand this effect. “
