Newly Identified Exoplanet HIP 67522b Causes Flares on Host Star

In a groundbreaking discovery, astronomers have observed that the newly identified exoplanet HIP 67522b triggers frequent flares on its parent star, HIP 67522, due to its close orbit. This phenomenon, detailed in a study published in the journal *Nature* on July 2, 2025, marks the first clear evidence of star-planet interaction leading to energetic eruptions from the star’s surface. The findings stem from data collected by NASA’s Transiting Exoplanet Survey Satellite (TESS) and the European Space Agency's CHaracterising ExoPlanets Telescope (CHEOPS).

HIP 67522 is a G0-type star located approximately 417 light-years away in the Centaurus constellation. The star is relatively young at about 17 million years old and is part of the Scorpius-Centaurus stellar association. It is host to at least two exoplanets, with HIP 67522b being a hot Jupiter that completes an orbit every seven days and is approximately ten times the diameter of Earth.

Astronomer Dr. Ekaterina Ilin from ASTRON, the Netherlands Institute for Radio Astronomy, led the research team. According to Dr. Ilin, the interaction between HIP 67522b and its star creates a strong bond that, while fascinating, is likely destructive. "The planet hooks into the star’s magnetic field, triggering flares that send energy back to HIP 67522b," Dr. Ilin stated. This energy influx causes heating and inflation of the planet’s atmosphere, raising concerns about its long-term stability.

Dr. Harish Vedantham, another astronomer at ASTRON, noted, "The planet is essentially subjecting itself to an intense bombardment of radiation and particles from these induced flares. This self-inflicted space weather likely causes the planet's atmosphere to puff up and may dramatically accelerate the rate at which the planet is losing its atmosphere."

The implications of these findings are significant. The continuous exposure to flares may lead to atmospheric loss, potentially reducing HIP 67522b's size over millions of years. Future projections suggest that it could transform into a hot Neptune or even a smaller sub-Neptune, a type of planet commonly found in our Galaxy but absent in our Solar System.

Dr. Katja Poppenhäger from the Leibniz-Institut für Astrophysik Potsdam emphasized the importance of this discovery, stating, "This type of star-planet interaction has been expected for a long time, but obtaining the observational evidence was only possible with this large space telescope dataset."

Additionally, the researchers conducted radio wave observations of HIP 67522 using the Australian Telescope Compact Array (ATCA) for approximately 135 hours. They confirmed that the star exhibits strong radio wave emissions powered by its magnetic field, although no radio wave flares attributable to the planet-induced activity were detected.

The research not only expands our understanding of exoplanetary atmospheres but also raises questions regarding the long-term evolution of such planets under intense stellar bombardment. As Dr. Ilin concluded, "We've found the first clear evidence of flaring star-planet interaction, where a planet triggers energetic eruptions on its host star."

This discovery could pave the way for further studies on exoplanet interactions and their atmospheres, contributing to the broader field of astrophysics and our understanding of planetary systems beyond our own.