A new study by NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton highlights the challenges planets face when orbiting red dwarf stars, the most common type of star in the universe.
The research focuses on the intense X-rays and ultraviolet (UV) radiation these stars emit and how they might affect planets around them.
The star Wolf 359, a red dwarf located just 7.8 light-years from Earth, was the focus of this study.
Red dwarfs are smaller and cooler than our Sun, but they are extremely long-lived, giving life plenty of time to develop.
Wolf 359 is one of the closest stars to our solar system, making it an excellent candidate for studying the potential for life on planets orbiting red dwarfs.
“Wolf 359 helps us understand how stars like it can impact habitability,” said Scott Wolk, the study’s lead author from the Center for Astrophysics | Harvard & Smithsonian (CfA). “It’s close to Earth and belongs to the most common class of stars, making it a great case study.”
Although scientists haven’t confirmed planets around Wolf 359, there is evidence of two possible planets orbiting the star.
However, neither of these planets lies in the “habitable zone,” the region where liquid water could exist on the surface. One planet appears too close to the star, while the other is too far away.
The study explored what it would take for a planet in the habitable zone of Wolf 359 to support life. The researchers found that intense radiation from the star poses a significant challenge.
A planet would need a strong greenhouse gas layer, similar to Earth’s atmosphere with carbon dioxide, to protect itself and trap heat.
Additionally, it would need to be at the outer edge of the habitable zone to minimize the effects of harmful radiation.
“The steady radiation alone could strip away a planet’s atmosphere in a million years if it’s too close to the star,” said co-author Ignazio Pillitteri of CfA and Italy’s National Institute for Astrophysics. “Only planets with specific conditions could sustain an atmosphere long enough for life to develop.”
Another threat comes from X-ray flares—intense bursts of radiation from the star. Over 3.5 days of observation, 18 X-ray flares were detected on Wolf 359.
More powerful flares likely occur over longer periods, making the environment even harsher for planets.
The team concluded that only planets at the outer edge of the habitable zone, with strong greenhouse gases, could retain their atmospheres long enough for complex life to develop. Even then, it would be a tough environment for life as we know it.
These findings were shared at the American Astronomical Society’s meeting and will be published in an academic journal. They underline the challenges of finding habitable planets around red dwarfs, despite these stars being the most common in the universe.
Source:NASA.
