Solar flares are so destructive, why can humans still survive? Saved by the Earth itself

Stellar flares are sudden flashes of magnetic images. On Earth, solar flares sometimes damage satellites and disrupt radio communications. Elsewhere in the universe, powerful stellar flares also have the ability to deplete and destroy atmospheric gases such as ozone. Without ozone, harmful levels of ultraviolet (UV) radiation could penetrate a planet's atmosphere, reducing the chances of life on its surface. A new study from Northwest University shows that despite their power and unpredictability, stellar flares emitted by planetary hosts do not necessarily prevent the formation and birth of life.

By combining 3D atmospheric chemistry and climate modeling with observed data on distant stellar flares, a Northwestern University research team found that stellar flares may play an important role in the long-term evolution of planetary atmospheres and habitability . "We compared the atmospheric chemistry of planets that experience frequent flares with those of planets that don't," said Howard Chen of Northwestern University and lead author of the study. The long-term atmospheric chemistry is very different. Continuous flares actually push the composition of a planet's atmosphere toward a new chemical equilibrium. Daniel Horton, senior author of the study, added:

We found that stellar flares may not rule out the presence of life, and in some cases the flares do not eat away all of the atmosphere Ozone, surface life may still have a chance to survive or be born. Their study, published in the journal Nature Astronomy, was led by researchers from Northwestern University, the University of Colorado Boulder, the University of Chicago, MIT and NASA's Center for Science Research on Exoplanetary Systems (NExSS)*** The result of joint efforts. Horton is an assistant professor of Earth and planetary sciences in Northwestern's Weinberg College of Arts and Sciences, and Chen is a doctoral student in Horton's climate change research group and a future NASA researcher.

All stars (including our sun) produce flares, or random releases of stored energy. Fortunately for life on Earth, solar flares usually have minimal impact on Earth. "The sun is more like a gentle giant," said study co-author Alison Youngblood, an astronomer at the University of Colorado. "It's older and not as active as younger, smaller stars. Earth also has a strong The magnetic field can deflect the sun's destructive solar wind. Unfortunately, most potentially habitable exoplanets are not so lucky.

For a planet to potentially harbor life, it must be close enough to the star that the water does not freeze (like Uranus), but not so close that the water evaporates (like Mercury) . Astronomers studied planets orbiting within the habitable zones of M and K dwarf stars, the most common stars in the universe. The habitable zone is narrow around these stars because these stars are smaller and weaker than stars like the Sun. M and K dwarfs, on the other hand, are thought to have more frequent flare activity than the Sun, and they are tidally locked planets that are less likely to have magnetic fields to help deflect stellar winds.

Astronomers have previously studied long-term climate averages of M dwarf star systems. However, flares occur on time scales of hours or even days. While these brief timescales can be difficult to simulate, incorporating the effects of flares is important in forming a more complete picture of exoplanet atmospheres. The researchers achieved this by incorporating into their simulations data from flares observed by TESS, NASA's transiting exoplanet satellite launched in 2018.

If life existed on these M and K dwarf planets, previous research hypothesized that stellar flares might make it easier to detect. Stellar flares, for example, can increase the abundance of life-indicating gases such as nitrogen dioxide, nitrous oxide and nitric acid from imperceptible levels to detectable levels. Space weather events are often thought of as a detriment to habitability, but research shows quantitatively that some space weather can actually help us detect important gas signatures that may represent biological processes.

The study involved researchers from a wide range of backgrounds and expertise, including climatologists, exoplanet scientists, astronomers, theorists and observers. Eric T. Wolf, a planetary scientist at the University of Colorado Boulder (CU Boulder) and co-author of the study, said: This project is the result of an outstanding team collaboration in the study of extrasolar planets. conditions, research efforts highlight the benefits of interdisciplinary efforts.