When researchers discovered an exoplanet around our nearest star four years ago, it seemed the perfect object where a research mission could begin in hopes of finding life. But then further research showed that Proxima b was exposed to regular ejections of radiation from a nearby star in the form of stellar flashes, shattering hopes that the planet could be habitable.
But now a new study by scientists from Northwestern University says that star flares aren’t really that bad a thing and could play an important role in the long-term development of the planet’s atmosphere and habitability.
With a huge human population dependent on satellites on a daily basis, stellar flashes from Earth’s perspective are not so bright.
They may seem beautiful if viewed from afar, but the very high-energy particles emitted by the Sun can affect electrical networks, bathe aircraft on high flights, disrupt satellites, and even cause them to crash.
There are also dangerous solar storms in space. If an unarmored astronaut receives large enough doses of radiation, it can have fatal consequences for the unfortunate recipient.
The situation is not improving elsewhere in space either, as robust star torches have the ability to deplete and destroy atmospheric gases, such as ozone (O3).
Ozone is a key molecule on Earth because it helps block harmful levels of ultraviolet (UV) radiation from reaching the ground. If it is allowed to penetrate unhindered through the atmosphere of our planet, it could have a detrimental effect on surface life.
But despite the damage these unpredictable and often violent stellar torches can do, it may not all be doom and gloom.
After extensively studying the planets orbiting the inhabited zones of dwarf M and K stars – the most common stars in space – the research team used a combination of 3D atmospheric chemistry and climate modeling to see what effects rockets have on exoplanet habitat.
“The habitable zones around these stars are narrower because stars are smaller and less powerful than stars like our sun. On the other hand, dwarf stars M and K are thought to have more frequent flaming activities than our sun, and their planets are tidal locked are unlikely that magnetic fields will help deter their stellar winds, ”says Daniel Horton, assistant professor of Earth and Planetary Sciences at the Weinberg College of Arts and Sciences and senior author of the study.
Their study was by no means an easy task as torches can last for hours or days and as such these short time frames can be difficult to simulate.
To create a more complete picture of the exoplanet’s atmospheres, the researchers incorporated flare data from NASA’s Transiting Exoplanet Satellite Survey, launched in 2018, into their model simulations.
The team, made up of scientists from Northwestern, the University of Colorado at Boulder, the University of Chicago, the Massachusetts Institute of Technology and NASA’s Nexus Exoplanet Science (NExSS), found that surprising, stellar torches emitted by a host planet do not necessarily prevent the creation of life.
“We compared the atmospheric chemistry of planets that experience frequent torches and planets that do not have torches. Long-term atmospheric chemistry is very different,” said Howard Chen of Northwestern, the study’s first author. “Continuous torches actually lead the planet’s atmospheric composition to a new chemical equilibrium.”
“We discovered that star torches may not prevent the existence of life,” Horton added. “In some cases, flames don’t corrode all the atmospheric ozone. Surface life may still have a chance to fight.”
Moreover, stellar torches can make it easier to detect life if it has been established. This is because stellar flares can increase the abundance of life-giving gases such as nitrous dioxide, nitric oxide, and nitric acid, from barely being there to observable levels.
“Space weather events are usually considered damage to habitability,” Chen said. “But our study quantitatively shows that some spacetime can actually help us discover the signatures of important gases that could denote biological processes.”
The team’s study, “Persistence of Atmospheric Chemistry Powered by Torches in Rocky Habitats,” was published this week in the journal Nature Astronomy.