Stars have an antiaging trick that humans cannot even imagine: their families.
Astronomers discovered that the presence a right-sized planet orbiting its parent at a fast enough speed seems to slow down the star’s age process. A closely orbiting gas giant can transfer the star’s angular momentum to its spin, countering the slow loss of rotation caused by the star’s magnetic field’s braking effect.
It is difficult to determine the impact of exoplanets upon the rotation of host star stars. You can’t see the effect of a planet on the speed of the planet’s rotation if you only look at one star.
Many stars are found in multi-star systems, however. Binary stars are typically stellar twins. They are born in the exact same nebula from the same cluster of dust or gas. Because they are so similar, their properties can often be very similar. They share a similar color and size as well as brightness and rotation.
A team of astronomers, led by Nikoleta Illic from the Leibniz Institute for Astrophysics Potsdam, conducted the equivalent to a twin study for stars.
They searched binary star systems in which one star had exoplanets orbiting it and the other didn’t. They used the star without a planet as a control star to examine the potential changes caused by the orbit of the other star.
However, a single star system is not enough to create a pattern. The team carefully examined 34 binaries during their study.
“In medicine, it is necessary to have a large number of patients in a study before you can determine if the results are real or outliers.” Ilic says. “The same is true in astronomy. This study gives us confidence that hot Jupiters are making stars orbiting them appear younger than they really are.”
Hot Jupiters are strange. They’re gas giants. Jupiter, but they hang out incredibly close to their host stars – with orbital periods of days or even hours. They are then superheated by the star and earn their title.
Ilic and her coworkers studied X-ray data from their 34 binary systems. This data was obtained from NASA’s Chandra observatory. They were able to identify a significant difference in the rotation rates of binary stars, as stars that spin faster have more X-ray activity.
The fastest stars had hot Jupiters. Giants that orbited farther from their star did not have any observable effects. This excludes our Sun (sorry Sun).
Because star rotation slows with time, stars younger than others tend to spin more quickly than those older stars that have similar properties. This means that hot Jupiters act as wrinkle cream for star stars. The star and exoplanet interact, resulting in spin being transferred to the star. This boosts the spin of both the former.
The details of the interaction are still a mystery. Ffor the sake or their analysis.The researchers believed it was tidal due to the gravitational attraction of the two bodies. However, magnetic forces may play a part. Further research could reveal the details.
“In past cases, there were many intriguing hints. However, now we have statistical proof that some planets influence their stars and keep them young.” says astronomer Marzieh HosseiniAIP.
“Hope future studies will uncover more systems to better understand the effect.”
The results of the research were published in Monthly Notices of The Royal Astronomical Society.
