Young sun-like star shows a magnetic field was critical for life on the early Earth
Kappa Ceti, located 30 light-years away in the constellation Cetus, the Whale, is remarkably similar to our Sun but younger. The team calculates an age of only 400-600 million years old, which agrees with the age estimated from its rotation period (a technique pioneered by CfA astronomer Soren Meibom). This age roughly corresponds to the time when life first appeared on Earth. As a result, studying Kappa Ceti can give us insights into the early history of our solar system.
|Observations taken with the 2.0-meter Bernard Lyot Telescope at Pic du Midi Observatory|
in France show that Kappa Ceti is a Sun-like star with an age of 400 - 600 million years
[Credit: Jose-Dias Do Nascimento]
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 early Earth didn't have as much protection as it does now, but it had enough," says Do Nascimento.
Kappa Ceti also shows evidence of "superflares" -- enormous eruptions that release 10 to 100 million times more energy than the largest flares ever observed on our Sun. Flares that energetic can strip a planet's atmosphere. By studying Kappa Ceti, researchers hope to learn how frequently it produces superflares, and therefore how often our Sun might have erupted in its youth.
This research has been accepted for publication in The Astrophysical Journal Letters and is available online.
Source: Harvard-Smithsonian Center for Astrophysics [March 16, 2016]