Planets can force their host stars to behave younger than normal for their age. This is shown by a new study of multiple systems by scientists at the Leibniz Institute for Astrophysics Potsdam (AIP) using NASA’s Chandra X-ray Observatory. This may be the best evidence yet that some planets are slowing the aging process of their host stars. Press release from the Leibniz Institute for Astrophysics Potsdam (AIP).
Source: AIP 2 November 2022.
November 2, 2022 — While the “anti-aging effect” of hot Jupiters, that is, giant gaseous exoplanets orbiting a star on or near Mercury, has been observed before, new observations now systematically document the effect and become the first The times thus provide the strongest evidence for this exotic phenomenon to date.
“In medicine, you need a lot of people participating in the study to know whether the effects are real or some sort of outlier,” says Nicoletta Ilic, PhD student in the Department of Stellar Physics and Exoplanet. AIP and first author of the study. “The same thing happens sometimes in astronomy, and this study leads us to believe that these hot Jupiters actually make the stars that orbit them look smaller than they are.”
A hot Jupiter can affect its host star through tidal forces, causing the star to spin faster than if it had no such planet. This rapid rotation may make the host star more active and produce more X-rays, which may indicate a younger age for the star.
However, as with humans, there are many factors that can determine the vitality of a star. As we age, all stars slow down their rotation and activity and experience fewer explosions. Since it is difficult to accurately determine the age of most stars, astronomers have previously found it difficult to determine whether a star is unusually active because it is being affected by a nearby planet that makes it appear younger than it. , or because he’s really young.
The researchers tackled this problem by studying binary systems in which stars are widely separated but only one of them is orbited by a hot Jupiter. Astronomers know that stars form together in binary star systems, like human twins. The distance between the stars is too great for them to affect each other or for a hot Jupiter to affect another star. This means they can use the planet-free star in the system as a “control subject”.
“It’s almost like using twins in a study where one twin lives in a completely different environment that affects their health,” said co-author Prof. Doctor. Katja Poppenhager, Head of the Department of Stellar Physics and Exoplanets AIP, “Comparing a star to a nearby planet without one of its twins, we can examine differences in the behavior of stars of the same age.”
The team observed X-rays emitted by stars using the Chandra and XMM-Newton Space Telescopes to determine how ‘young’ a star is. They looked for signs of the effects of their planets on stars by studying about three dozen systems in X-ray light. They found that stars with hot Jupiters are brighter in X-ray light and thus more active than their non-hot Jupiter peers.
“Previous cases have yielded some very intriguing clues, but now we finally have statistical evidence that some planets are actually influencing their stars and keeping them young,” said co-author Marzih Hosseini AIP– researcher. “We hope that future studies will help find more systems to better understand this effect.”
Tidal star–planet interactions and its effect on stellar activity in planet-hosting wide binary systems were observed. N. Ilick, K. Poppenhager, S. Marzih Hosseini, 2022, MNRAS, 513, 3, 4380, doi.org/10.1093/mnras/stac861, https://academic.oup.com/mnras/article-abstract/513/3/4380/6564186, https://arxiv.org/abs/2203.13637PDF: https://arxiv.org/pdf/2203.13637.pdf,
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