The Hot-Jupiter exoplanet HIP 67522b revolves around its star, HIP 67522, frequently triggering flares from the star’s surface, which seem to heat and penetrate the planet’s atmosphere.
HIP 67522 is a G0 star located approximately 417 light-years away in the constellation Centaurus.
This star is part of the Scorpius-Centaurus Stellar Association and is also known as HD 120411, 2Mass J13500627-4050090, and TYC 7794-2268-1.
At about 17 million years old, HIP 67522 is home to two young exoplanets.
The inner planet, HIP 67522b, completes an orbit around the star every seven days and has a diameter roughly ten times that of Earth, making it similar in size to Jupiter.
Using five years of data from NASA’s TESS and ESA’s CHEOPS telescopes, astronomer Ekaterina Ilin and her team studied the HIP 67522 system in detail.
They uncovered that the planet and its host star share a powerful yet destructive connection.
Although not completely understood, the planet becomes ensnared in the star’s magnetic field, resulting in eruptions on the star’s surface that transfer energy back to the planet.
When combined with other high-energy radiation from the star, these flares appear to significantly enhance the rapid inflation of the planet’s atmosphere.
This indicates that the planet might not remain within the size range of Jupiter for much longer.
Continuous exposure to intense radiation can lead to atmospheric loss over time.
In about 100 million years, this could change the planet into a hot Neptune state or even result in more severe atmospheric reductions, with sub-Neptunes commonly observed in our galaxies, but lacking smaller planetary types than Neptune in our solar system.
“We found the first definitive evidence of the interaction between the flare star and the planet, demonstrating that the planet induces energy eruptions in the host star,” remarked Dr. Ilin, lead author of a paper published in the journal Nature.
“What is particularly thrilling is that this interaction persists for at least three years, allowing for in-depth study.”
“Such planetary interactions have long been anticipated, but these observations were made possible with this extensive spatial telescope dataset,” stated Dr. Katja Poppenhäger, an astronomer at Leibniz-Institut für Astrophysik Potsdam and Potsdam University.
“The planets are essentially subjected to intense bursts of radiation and particles from these induced flares,” explained Astron astronomer Dr. Harish Vedantum.
“The conditions in this self-inflicted environment are likely to expand the planet’s atmosphere and can significantly accelerate the rate at which the planet is losing its atmosphere.”
In a separate paper published in Astronomy and Astrophysics, astronomers confirmed that HIP 67522 is a magnetically active star emitting strong radio radiation along with a magnetic field.
They monitored the star at low radio frequencies for approximately 135 hours using the Australian Telescope Compact Array (ATCA), revealing it as a bright and explosive source of radio waves.
However, there were no indications of radio wave flares resulting from star-planet interactions.
“The lack of detection aligns with the notion that planet-driven flares may be too faint for ATCA to observe, corroborating the conclusions on magnetic star-planet interactions presented in our Nature paper,” they noted.
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Ekaterina Ilin et al. Nearby planets induce flares in their host star. Nature, published online July 2, 2025. doi:10.1038/s41586-025-09236-z
Ekaterina Ilin et al. 2025. Search for planetary-induced radio signals from the young exoplanet-host star HIP 67522. A&A, in press; doi: 10.1051/0004-6361/202554684
Source: www.sci.news
