red dwarf star and planets

Red Dwarf Flares: Stars’ Volatile Nature May See Exoplanets Not So Habitable After All

There has been a considerable discussion concerning red dwarf stars and the chances that their planetary trains may be the best places to look when searching for alien life. However, some researchers are now questioning that this may be so, given that red dwarfs are extremely volatile at an early stage in their development, perhaps even so volatile — in the manifestation of stellar flares — that living organisms are not given the chance to gain a foothold on their respective exoplanets.

With the detection of seven Earth-size exoplanets — three of which were found to be within the star’s habitable zone — orbiting TRAPPIST-1 in February, astronomers began to think that the discovery might be an indication that red dwarf stars, due to their being the Milky Way galaxy’s most plentiful and long-lived stars, should be the go-to stars in the search for habitable exoplanets and, by extension, the possibility of life on said worlds. But researchers at Space Telescope Science Institute (STScI) in Baltimore, Cosmos magazine reports, questioned that, since red dwarfs are prone to intense flares (not unlike those emitted by the Sun) at a young age, the cool stars might not be as hospitable to life on their planets after all.

“What if planets are constantly bathed by these smaller, but still significant, flares?” asks Scott Fleming of STScI.

“There could be a cumulative effect.”

barren planet under red dwarf star
A number of flares from red dwarf stars may be as effective at stripping the worlds of their atmospheres, potentially rendering them lifeless, as a few intense flares. [Image by manjik/Shutterstock]

To answer the question, the team, led by Chase Million, reprocessed, through the gPhoton project, more than 100 terabytes of NASA’s GALEX (Galaxy Evolution Explorer) data stored in the Mikulski Archive for Space Telescopes (MAST), located at STScI. Analysis of the data was conducted through software created by Million and Clara Brasseur (also from STScI) to study hundreds of red dwarfs. What they found was that dozens of flares occurred in relatively short periods of time.

“We have found dwarf star flares in the whole range that we expected GALEX to be sensitive to, from itty bitty baby flares that last a few seconds, to monster flares that make a star hundreds of times brighter for a few minutes,” said Million.

As an earlier NASA report explained, the smaller flares, which are relatively dim in ultraviolet light from the red dwarfs, “although individually less energetic and therefore less hostile to life, smaller flares might be much more frequent and add up over time to create an inhospitable environment.”

Of course, large flares can also cause problems, stripping away a planet’s atmosphere. Both the intense flares and the persistent, less-intense flares can then penetrate to a planet’s surface and potentially damage prebiotic substances and living organisms, thereby preventing life from arising on red dwarf exoplanets.

Red dwarf star irradiates planet
Flares from a red dwarf star may make them less habitable than previously thought. [Image by Maxal Tamor/Shutterstock]

In fact, this outcome, that red dwarf stars may not produce a treasure trove of habitable exoplanets, was offered up by astrophysicist Neil DeGrasse Tyson shortly after the TRAPPIST-1 planets made headlines. He noted that red dwarfs, especially those in their younger stages, where highly volatile and their flares could possibly render any potentially habitable exoplanet into a barren, irradiated world not in the least hospitable to life as we know it.

[Featured Image by Jurik Peter/Shutterstock]