Clingy planets can trigger own doom, suspect Cheops and TESS

Written by Copernical Team Wednesday, 02 July 2025 14:00

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Exoplanet HIP 67522 b triggers flares from its host star (artist’s impression)

Astronomers using the European Space Agency’s Cheops mission have caught an exoplanet that seems to be triggering flares of radiation from the star it orbits. These tremendous explosions are blasting away the planet’s wispy atmosphere, causing it to shrink every year.

This is the first-ever evidence for a ‘planet with a death wish’. Though it was theorised to be possible since the nineties, the flares seen in this research are around 100 times more energetic than expected.

This planet's star makes our Sun look sleepy

Exoplanet HIP 67522 b orbiting close to its host star

Thanks to telescopes like the NASA/ESA/CSA James Webb Space Telescope and NASA’s Transiting Exoplanet Survey Satellite (TESS), we already had some clues about this planet and the star it orbits.

The star, named HIP 67522, was known to be just slightly larger and cooler than our own host star, the Sun. But whilst the Sun is a middle-aged 4.5-billion-year-old, HIP 67522 is a fresh-faced 17-million-year-old. It bears two planets. The closer of the two – given the catchy name HIP 67522 b – takes just seven days to whip around its host star.

Because of its youth and size, scientists suspected that star HIP 67522 would churn and spin with lots of energy. This churning and spinning would turn the star into a powerful magnet.

Our much-older Sun has its own smaller and more peaceful magnetic field. From studying the Sun, we already knew that flares of energy can burst from magnetic stars when ‘twisted’ magnetic field lines are suddenly released. This energy can take the form of anything from gentle radio waves to visible light to aggressive gamma rays.

A la carte research with Cheops

Ever since the first exoplanet was discovered in the 1990s, astronomers have pondered whether some of them might be orbiting close enough to disturb their host stars’ magnetic fields. If so, they could be triggering flares.

A team led by Ekaterina Ilin at the Netherlands Institute for Radio Astronomy (ASTRON) figured that with our current space telescopes, it was time to investigate this question further.

“We hadn’t seen any systems like HIP 67522 before; when the planet was found it was the youngest planet known to be orbiting its host star in less than 10 days,” says Ekaterina.

The team was using TESS to do a broad sweep of stars that might be flaring because of an interaction with their planets. When TESS turned its eyes to HIP 67522, the team thought they could be on to something. To be sure, they called upon ESA’s sensitive CHaracterising ExOPlanet Satellite, Cheops.