The bigger they come…
Using the Evryscope (left) and TESS (right), astronomers at UNC studied superflares from stars that could affect the development of life on distant world. Image credit: UNC (left) and NASA/GSFC (right)
Solar flares take place on our own Sun, but the vast majority of these are fairly small and well-contained. However, some stars produce superflares — stellar eruptions 10 to 1,000 larger than anything seen on the Sun. Such eruptions produce powerful outbursts of ultraviolet radiation capable of wiping out life on planets in orbit around the star.
The team observed target stars using the UNC-Chapel Hill Evryscope telescope array and NASA’s Transiting Exoplanet Survey Satellite (TESS), seeking to understand how superflares affect exoplanets.
Researchers found a relationship between the size of a superflare and its temperature. The amount of radiation released by superflares is dependent on temperature, connecting the size of the flare to the amount of energy released.
Superflares generally emit the majority of their energy over a short 15-minute period. Observations were taken by astronomers every two minutes, producing data throughout the events.
Superflares could supply most of the ultraviolet radiation affecting biological processes on alien worlds.
If such flares erupt at temperatures over 8,700 degrees Celsius (15,700 Fahrenheit), ultraviolet radiation could be 10 times greater than would be expected from studying just visible light from the events, the study found. This finding could potentially change our understanding of how superflares affect exoplanets.
“However, it is unknown for how long M-dwarf superflares reach temperatures above 9000 K. Only a handful of M-dwarf superflares have been recorded with multi-wavelength high-cadence observations,” researchers wrote in an article in the Astrophysical Journal detailing their study. The video below shows an interview with Scott Lambros, providing the latest updates for the James Webb Space Telescope.