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Without a magnetic field around Earth, life wouldn’t exist. Plain and simple. The evidence of this is right around us. Earth? It has a magnetic field and plenty of life. Mars? It used to have a major magnetic field, but it is far weaker today. A quick look at Mars tells us everything we need to know about life on the red planet. It doesn’t exist. At least, not today. We’re still looking for signs of life in its ancient past.
A new study is out from the Harvard-Smithsonian Center for Astrophysics, and it looks at a star much younger than the Sun. 30 light-years away in the constellation Cetus sits a star that is a lot like ours, but much younger. A team of scientists estimates Kappa Ceti is just 400-600 million years old. About the same age as the Sun when life first formed on Earth.
By studying Kappa Ceti, the scientists hoped to learn more about what the early solar system looked like. Specifically, the solar activity from the early Sun and its impacts on Earth.
Kappa Ceti is active. Very active. Sunspots the size of Earth are common on the Sun. And those are the small ones. Kappa Ceti’s starspots (sunspots, but on different stars) are even bigger, and there are a whole lot more of them.
All of Kappa Ceti’s solar activity is stronger. A steady stream of plasma, or ionized gas, pours into the surrounding space from the active star. The team of scientists says this solar wind is 50 times stronger than our Sun’s. This strong of a solar wind would test any planet within the habitable zone.
Kappa Ceti’s magnetic field
“To be habitable, a planet needs warmth, water, and it needs to be sheltered from a young, violent Sun,” says lead author Jose-Dias Do Nascimento of the Harvard-Smithsonian Center for Astrophysics (CfA) and University of Rio G. do Norte (UFRN), Brazil.
Some planets, like Earth, can take the beating. Others, like Mars, succumb to the stellar onslaught and lose their atmosphere. Mars was once warm enough to host oceans but today, it’s a cold, arid world.
Using computer models, scientists wanted to see how the early Earth could hold up against Kappa Ceti’s fierce solar wind. Earth’s magnetic field is believed to be around the same strength back then as it is today. Maybe slightly weaker. If Earth was orbiting Kappa Ceit, the magnetosphere would be about one-third to one-half as large as it is today. Life would have pulled through, though.
“The early Earth didn’t have as much protection as it does now, but it had enough,” says Do Nascimento.
Observations of Kappa Ceti also hint at ‘superflares.’ Take the largest flare ever observed on our Sun and multiply it by 10 to 100 million times. Scientists will keep an eye on Kappa Ceti to hopefully learn how frequently these stellar eruptions happen. And how frequently they may have occured on the early Sun.
Are we alone in the Universe?
It’s the biggest question in all of science. And studying stars like Kappa Ceti helps. As the next generation of telescopes come online, astronomers need to figure out ways to narrow the search. Finding the most suitable stars for life is a good place to start.
Kappa Ceti shows planets with a similar magnetic field to Earth can survive the intense solar activity of young stars. As we improve our understanding of how stars and planets interact – we’ll be able to find exoplanets, study their stars and determine if they are good candidates for additional study.