Red dwarf stars can produce stellar flares emitting far-ultraviolet (far-UV) radiation at levels much higher than previously believed
This discovery suggests that the intense UV radiation from these flares could significantly impact the habitability of planets orbiting red dwarf stars.
The research, led by current and former astronomers from the University of Hawaii Institute for Astronomy (IfA), was recently published in the Monthly Notices of the Royal Astronomical Society.
“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 conducted the study while participating in the Research Experiences for Undergraduates program at IfA, an initiative supported by the National Science Foundation. Berger and her team used archival data from the GALEX space telescope to search for flares among 300,000 nearby stars.
GALEX, a now-decommissioned NASA mission, observed most of the sky at near-and far-UV wavelengths from 2003 to 2013. With new computational techniques, the team revealed new insights from the data.
“Combining modern computer power with gigabytes of decades-old observations allowed us to search for flares on thousands and thousands of nearby stars,” said Michael Tucker, a PhD graduate of IfA and now a postdoctoral fellow at Ohio State University.
The double-edged sword of UV radiation
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, showing 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.
“A change of three is the same as the difference in UV in the summer from Anchorage, Alaska to Honolulu, where unprotected skin can get a sunburn in less than 10 minutes,” explained Benjamin J. Shappee, an Associate Astronomer at IfA who mentored Berger.
Uncovering the hidden causes
The exact cause of this stronger far-UV emission remains unclear. The team believes that flare radiation might be 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 flares,” said Jason Hinkle, a PhD candidate at IfA who co-authored the study.
According to Berger, now a Churchill Scholar at the University of Cambridge, more data from space telescopes is needed to study the UV light from stars, which is crucial for understanding the source of this emission. This research paves the way for future studies to explore the habitability of exoplanets around red dwarf stars and the role of UV radiation in the development of life.
Conclusion
This discovery not only challenges our understanding of stellar flares but also raises new questions about the potential for life on planets orbiting red dwarf stars. With more advanced space telescopes and continued research, scientists hope to uncover the mysteries of these distant worlds and the stars they orbit.
