Most people point toward Earth’s rocky surface, the presence of water, and its unique atmosphere when asked what led to the first appearance of life on Earth nearly four billion years ago.
While this is true, a new study has now revealed a lesser-known necessary ingredient that also played an important role in its evolution; the presence of a protective magnetic field.
The new study, published in The Astrophysical Journal Letters, focuses on a young sun-like star called Kappa Ceti, that shows that a magnetic field plays a key role in making a planet conducive to life.
Lead author Jose-Dias Do Nascimento of the Harvard-Smithsonian Center for Astrophysics (CfA) and University of Rio G. do Norte (UFRN), Brazil, said in a statement:
“To be habitable, a planet needs warmth, water, and it needs to be sheltered from a young, violent sun.”
Kappa Ceti is situated 30 light-years away in the constellation Cetus, and is extraordinarily similar to our sun, although it is much younger.
The team has calculated its age to be only 400-600 million years old, and this matches its age that was estimated using its rotation period (a technique pioneered by CfA astronomer Soren Meibom).
This age corresponds to around the same time as when life first appeared on Earth. It is because of this researchers believe that Kappa Ceti could reveal insights into the early history of our solar system.
Being very magnetically active, Kappa Ceti is similar to other stars its age. Its surface has many giant starspots — similar to sunspots — however they are larger, and more numerous.
During their observations the team also discovered Kappa Ceti releases a steady stream of plasma, or ionized gases, out into space, and that the stellar winds are 50 times stronger than our own sun’s solar wind.
According to a Harvard-Smithsonian Center for Astrophysics statement:
“Such a fierce stellar wind would batter the atmosphere of any planet in the habitable zone, unless that planet was shielded by a magnetic field.
“At the extreme, a planet without a magnetic field could lose most of its atmosphere. In our solar system, the planet Mars, suffered this fate and turned from a world warm enough for briny oceans to a cold, dry desert.”
The researchers then modeled how Kappa Ceti’s strong stellar winds would have affected a young Earth. The magnetic field of early Earth is predicted to have been around the same strength as it is today, or possibly slightly weaker.
Depending on the assumed strength, the researchers found that the resulting protected region, or magnetosphere, of Earth would be about one-third to one-half as large as it is today, according to the study.
Do Nascimento explained:
“The early Earth didn’t have as much protection as it does now, but it had enough.”
There is also evidence that Kappa Ceti is capable of producing “superflares,” these are massive eruptions releasing 10 to 100 million times more energy than the largest flares we have observed from our own sun. Superflares are also capable of striping a planet’s atmosphere.
The researchers are hoping by studying Kappa Ceti they can gain insight into how frequently it produces superflares, which would then give a better understanding on how often our sun may have erupted in its youth.