Red dwarfs, also known as M-class stars, have long intrigued astronomers and astrobiologists due to their stability and abundance in our galaxy.
Cool and small compared to our Sun, these stars burn their hydrogen fuel slowly, granting them extensive lifespans.
Remarkably, they make up about 70% of the stars in the Milky Way, providing ample opportunities for finding Earth-like planets within their orbit that could potentially support life.
However, there’s a hitch: these stars are notorious for emitting frequent stellar flares, which could pose significant hazards to surrounding planets.
Recently published research in the Monthly Notices of the Royal Astronomical Society sheds new light on the potential dangers posed by red dwarf stellar flares.
Analyzing a decade of data from the decommissioned GALEX space telescope, authors studied 182 particularly intense flares originating from M-class systems.
While earlier studies primarily focused on optical wavelength emissions, this research examined the ultraviolet (UV) radiation released during these events, particularly near UV (175–275 nm) and far UV (135–175 nm) ranges.
Stellar flares emitting high-energy photons can catalyze the formation of complex molecules necessary for life in some scenarios.
However, in excessive amounts, these photons could strip a planet of its atmosphere, including its life-protecting ozone layer.
Alarmingly, this new research suggests that previous estimates of UV radiation from these flares might have been underestimated.
Scientists typically model the electromagnetic radiation of flares following a blackbody distribution, assuming a temperature of approximately 8,727 degrees Celsius – a considerable jump from the cooler red dwarf surface temperatures, which range from about 1,727°C to 3,227°C.
However, the study indicates that flares from red dwarfs might not adhere to this distribution, as evidenced by 98% of the flares showing greater UV output than anticipated.
This finding indicates a need for new models to accurately predict the UV emissions these stellar phenomena produce.
The implications are significant: planets orbiting within red dwarf systems could be more hostile to life than previously believed.
Although they might sit within the habitable zone, their viability for life may be compromised by these unexpected bursts of UV radiation.
This means that astronomers may need to reassess the habitability of worlds around the galaxy’s most common stars.
The curiosity about whether extraterrestrial life could thrive within the reach of such ubiquitous stars has taken a backseat with these recent findings, urging scientists to re-evaluate the red dwarf systems previously considered prime candidates in the search for life beyond Earth.