In a study soon to be published in The Astrophysical Journal Letters, researchers report new findings on the star's behavior — and what that blustery weather might be able to tell us about the evolution of life on Earth and beyond.
"To be habitable, a planet needs warmth, water, and it needs to be sheltered from a young, violent Sun," lead author Jose-Dias Do Nascimento of the Harvard-Smithsonian Center for Astrophysics and University of Rio G. do Norte said in a statement.
The researchers figure that Kappa Ceti, being quite sun-like, could provide a good approximation for the kind of violence our own planet had to endure just as life began.
And by figuring that out, scientists can start to determine how "normal" our solar system is. How many Earth-like planets have the kind of protection our own planet did, during these rough and rowdy adolescent years? Knowing that will help answer the enduring question of how likely life is to evolve on other planets — and it will help us know what signs to look for when we're trying to track down planets as resilient as our own.
Right now, the roughly 500-million-year-old Kappa Ceti is spewing out solar winds some 50 times stronger than those ejected from our own sun. It also has occasional superflares that emit 10 to 100 million times more energy than the largest flares ever observed in our own solar system.
Stellar winds aren't much of a problem for Earth today: Between the decreased activity of our middle-aged sun and our planet's robust magnetic field, most of the energetic particles break through only at the planet's poles. These sometimes cause electrical issues, but mostly just give us stunning stellar light shows in the form of aurorae. And because of our planet's strong magnetic field, even long-ago superflares wouldn't have kept life from evolving.
"As it turns out, our magnetic field would have been enough, even if our sun was once as active as Kappa Ceti," University of Queensland researchers Jonti Horner and"The Earth’s shield, the magnetosphere, would have been compressed, shrunk to about one-third its current size. But it would have endured, protecting Earth and allowing our planet to remain habitable."
Mars serves as an excellent example of what happens when that protection isn't in place: Scientists believe that the planet is barren because it lacked Earth's strong magnetic field, leaving it vulnerable to the young sun's intense solar winds. The planet now has very little atmosphere to speak of, and it continues to be stripped away by high-energy particles from the sun.
So how typical is it for a planet orbiting a star like ours to end up as an Earth instead of a Mars? That's the million-dollar question that planetary scientists keep coming back to. When it comes to planetary habitability, we don't want to be special: The more normal we are, the more likely we are to find life somewhere else.