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Fast Company
07-07-2025
- Science
- Fast Company
This planet is drawing huge flares from its young star
Scientists are tracking a large gas planet experiencing quite a quandary as it orbits extremely close to a young star – a predicament never previously observed. This exoplanet, as planets beyond our solar system are called, orbits its star so tightly that it appears to trigger flares from the stellar surface – larger than any observed from the sun – reaching several million miles (km) into space that over time may strip much of this unlucky world's atmosphere. The phenomenon appears to be caused by the planet's interaction with the star's magnetic field, according to the researchers. And this star is a kind known to flare, especially when young. 'A young star of this type is an angry beast, especially if you're sitting as close up as this planet does,' said Netherlands Institute for Radio Astronomy astrophysicist Ekaterina Ilin, lead author of the study published in the journal Nature. The star, called HIP 67522, is slightly more massive than the sun and is located about 407 light-years from Earth in the constellation Centaurus. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). This star and planet, as well as a second smaller gas planet also detected in this planetary system, are practically newborns. Whereas the sun and our solar system's planets are roughly 4.5 billion years old, this star is about 17 million years old, with its planets slightly younger. The planet, named HIP 67522 b, has a diameter almost the size of Jupiter, our solar system's largest planet, but with only 5% of Jupiter's mass. That makes it one of the puffiest exoplanets known, with a consistency reminiscent of cotton candy (candy floss). It orbits five times closer to its star than our solar system's innermost planet Mercury orbits the sun, needing only seven days to complete an orbit. A flare is an intense eruption of electromagnetic radiation emanating from the outermost part of a star's atmosphere, called the corona. So how does HIP 67522 b elicit huge flares from the star? As it orbits, it apparently interacts with the star's magnetic field – either through its own magnetic field or perhaps through the presence of conducting material such as iron in the planet's composition. 'We don't know for sure what the mechanism is. We think it is plausible that the planet moves within the star's magnetic field and whips up a wave that travels along magnetic field lines to the star. When the wave reaches the stellar corona, it triggers flares in large magnetic field loops that store energy, which is released by the wave,' Ilin said. 'As it moves through the field like a boat on a lake, it creates waves in its wake,' Ilin added. 'The flares these waves trigger when they crash into the star are a new phenomenon. This is important because it had never been observed before, especially at the intensity detected.' The researchers believe it is a specific type of wave called an Alfvén wave, named for 20th century Swedish physicist and Nobel Prize laureate Hannes Alfvén, that propagates due to the interaction of magnetic fields. The flares may heat up and inflate the planet's atmosphere, which is dominated by hydrogen and helium. Being lashed by these flares could blast away lighter elements from the atmosphere and reduce the planet's mass over perhaps hundreds of millions of years. 'At that time, it will have lost most if not all the light elements, and become what's called a sub-Neptune – a gas planet smaller than Neptune,' Ilin said, referring to the smallest of our solar system's gas planets. The researchers used observations by two space telescopes: NASA's TESS, short for Transiting Exoplanet Survey Satellite, and the European Space Agency's CHEOPS, short for CHaracterising ExOPlanet Satellite. The plight of HIP 67522 b illustrates the many circumstances under which exoplanets exist. 'It is certainly no sheltered youth for this planet. But I am not sad about it. I enjoy diversity in all things nature, and what this planet will eventually become – perhaps a sub-Neptune rich in heavy elements that did not evaporate – is no less fascinating than what we observe today.'
Yahoo
02-07-2025
- Science
- Yahoo
'A completely new phenomenon': Astronomers spot a planet causing its star to constantly explode
When you buy through links on our articles, Future and its syndication partners may earn a commission. Astronomers have captured the first evidence of a "planet with a death wish" — an alien world that's orbiting so close to its star and so fast that it's causing the star to cook it to death with stellar explosions. The planet, called HIP 67522 b, is a wispy, Jupiter-size planet bound on a tight, seven-day orbit around its host star, HIP 67522. But these orbits are disturbing the star's magnetic field, causing enormous stellar eruptions to blow back on the planet and make it shrink. This marks the first time a planet has been observed influencing its host star, the scientists reported in a study published July 2 in the journal Nature. "The planet seems to be triggering particularly energetic flares," study first-author Ekaterina Ilin, an astrophysicist at the Netherlands Institute for Radio Astronomy, said in a statement. "The waves it sends along the star's magnetic field lines kick off flares at specific moments. But the energy of the flares is much higher than the energy of the waves. We think that the waves are setting off explosions that are waiting to happen." Stars are gigantic balls of burning plasma whose charged particles, or ions, swirl over their surfaces to create powerful magnetic fields. Because magnetic-field lines cannot cross each other, sometimes these fields knot before suddenly snapping to launch bursts of radiation called solar flares, which are sometimes accompanied by enormous belches of surface plasma known as coronal mass ejections. Because many planets, including Earth, have magnetic fields, astronomers have long wondered whether planets with close orbits around their stars could disturb powerful stellar magnetic fields enough to trigger explosions. Related: James Webb telescope discovers its first planet — a Saturn-size 'shepherd' still glowing red hot from its formation To investigate this question, the astronomers conducted a broad sweep of stars using NASA's Transiting Exoplanet Survey Satellite (TESS), which finds exoplanets by detecting the characteristic dimming of stars' light as planets pass in front of them. After flagging HIP 67522 as worthy of interest, the astronomers used the European Space Agency's (ESA) Characterising Exoplanet Satellite (Cheops) to investigate further. "We quickly requested observing time with Cheops, which can target individual stars on demand, ultra precisely," Ilin said. "With Cheops we saw more flares, taking the total count to 15, almost all coming in our direction as the planet transited in front of the star as seen from Earth." A vital piece of evidence was that these flares occurred when the planet passed in front of the star. This suggested that the planet is gathering energy as it orbits and is using it to "whip" the star's magnetic-field lines like a rope. When this shock wave passes down the field to the star's surface, a powerful flare erupts. RELATED STORIES —Scientists discover rare planet at the edge of the Milky Way, using space-time phenomenon predicted by Einstein —'Eyeball' planet spied by James Webb telescope might be habitable —Our sun may be overdue for a 'superflare' stronger than billions of atomic bombs, new research warns These flares are slowly stripping away the planet's diffuse atmosphere, layer by layer. The researchers project that, although HIP 67522 b is as big as Jupiter now, it could shrink to the size of Neptune in the next 100 million years. To further investigate this first-of-its-kind phenomenon, the researchers plan to take more readings with TESS, Cheops, and other exoplanet telescopes, such as ESA's upcoming Plato space telescope, which is scheduled to launch in 2026. "I have a million questions because this is a completely new phenomenon, so the details are still not clear," Ilin said. "There are two things that I think are most important to do now. The first is to follow up in different wavelengths (Cheops covers visible to near-infrared wavelengths) to find out what kind of energy is being released in these flares — for example ultraviolet and X-rays are especially bad news for the exoplanet. "The second is to find and study other similar star-planet systems; by moving from a single case to a group of 10-100 systems, theoretical astronomers will have something to work with," she added.
