A groundbreaking study has revealed that red dwarf stars can produce stellar flares that carry far-ultraviolet (far-UV) radiation levels much higher than previously believed.
This discovery suggests that the intense UV radiation from stellar flares could significantly impact whether planets around red dwarf stars can be habitable.
“Few stars have been thought to generate enough UV radiation through flares to impact planet habitability. Our findings show that many more stars may have this capability,” said astronomer Vera Berger, who led the study.
Led by current and former astronomers from the University of Hawaiʻi Institute for Astronomy (IfA), the research was recently published in Monthly Notices of the Royal Astronomical Society.
UV from stellar flares presents a double-edged sword
Berger and her team used archival data from the GALEX space telescope to search for stellar flares among 300,000 nearby stars.
“Combining modern computer power with gigabytes of decades-old observations allowed us to search for flares on thousands and thousands of nearby stars,” explained Michael Tucker, a PhD graduate of IfA and now a postdoctoral fellow at Ohio State University.
According to researchers, UV radiation from stellar flares can either erode planetary atmospheres, threatening their potential to support life or contribute to the formation of RNA building blocks, which are essential for the creation of life.
This study challenges existing models of stellar flares and exoplanet habitability. It shows that far-UV emission from flares is, on average, three times more energetic than typically assumed and can reach up to twelve times the expected energy levels.
Benjamin Shappee, an Associate Astronomer at IfA, commented: “A change of three is the same as the difference in UV in the summer from Anchorage to Honolulu, where unprotected skin can get a sunburn in less than ten minutes.”
Hidden causes of stronger UV emissions
The exact cause of this stronger far-UV emission remains unclear. The team believes it might be that flare radiation is concentrated at specific wavelengths, indicating the presence of atoms like carbon and nitrogen.
“This study has changed the picture of the environments around stars less massive than our Sun, which emit very little UV light outside of stellar flares,” concluded Jason Hinkle, a PhD candidate at IfA who co-authored the study.
The researchers said that more data from space telescopes is needed to study the UV light from stars, which is crucial for understanding the source of this emission.
