NASA researchers have come out with a model that provides a closer look at a nearby star thought to resemble our young Sun.
The work allows scientists to better understand what our Sun may have been like when it was young, and how it may have shaped the atmosphere of our planet and the development of life on Earth.
At 4.65 billion years old, our Sun is a middle-aged star. Scientists are often curious to learn exactly what properties enabled our Sun, in its younger years, to support life on nearby Earth.
Without a time machine to transport scientists back billions of years, retracing our star's early activity may seem an impossible feat. Luckily, in the Milky Way galaxy of ours, there are more than 100 billion stars and one in ten share characteristics with our Sun, many of them in the early stages of development.
Vladimir Airapetian, senior astrophysicist in the Heliophysics Division at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and first author on the new study said the scientists are "looking at characteristics of a young star similar to ours, to better understand what our own star was like in its youth, and what allowed it to foster life on one of its nearby planets."
Kappa 1 Ceti is one such solar analogue. Located about 30 light-years away and estimated to be between 600 to 750 million years old, it was around the same age our Sun was when life developed on Earth.
It also has a similar mass and surface temperature to our Sun, said the study's second author, Meng Jin, a heliophysicist with the SETI Institute and the Lockheed Martin Solar and Astrophysics Laboratory in California. All of those factors make Kappa 1 Ceti a "twin" of our young Sun at the time when life arose on Earth, and an important target for study.
Airapetian, Jin, and several colleagues have adapted an existing solar model to predict some of Kappa 1 Ceti's most important, yet difficult to measure, characteristics. The model relies on data input from a variety of space missions and the study was published in The Astrophysical Journal.
Stellar Wind
Stellar wind can have a significant impact on planets at any stage of life. But the strong, highly dense stellar winds of young stars can compress the protective magnetic shields of surrounding planets, making them even more susceptible to the effects of the charged particles.
Our Sun is a perfect example. Compared to now, in its toddlerhood, our Sun likely rotated three times faster, had a stronger magnetic field, and shot out more intense high-energy radiation and particles.
These days, for lucky spectators, the impact of these particles is sometimes visible near the planet's poles as aurora, or the Northern and Southern Lights. About 4 billion years ago, considering the impact of our Sun's wind at that time, these tremendous lights were likely often visible from many more places around the globe, said NASA researchers.
That high level of activity in our Sun's nascence may have pushed back Earth's protective magnetosphere, and provided the planet – not close enough to be torched like Venus, nor distant enough to be neglected like Mars – with the right atmospheric chemistry for the formation of biological molecules. Similar processes could be unfolding in stellar systems across our galaxy and universe.
