News Flash! Sun-Like Stars Are Sun-like

Breaking news: the Sun is a solar-type star!

Now, this might seem obvious, since “solar” is defined as being Sun-like, but up until now astronomers hadn’t actually confirmed that stars we call “Sun-like” or “solar-type” had consistent magnetic cycles like our very own Sun. A paper published today in Science, however, shows that many stars have magnetic activity predictably similar to the Sun.

Scientists from France, Canada, and the United States helped bring this revelation to light by creating 3D simulations revealing consistent similarities between the Sun and similar types of stars. To understand the premise behind their studies, we first have to understand something about the Sun. Our star goes through a regular, 11-year cycle, tied to magnetic field oscillations and cycles of more intense solar storms. We’ve known about this cycle since the 1800s, but the mechanism behind the cycles is complex and hard to define, and astronomers weren’t able to predict similar cycles in other stars.

The international collaboration of astronomers devised a computer simulation to model the interiors of stars similar to the Sun—a critical step because activity inside the stars helps explain how their magnetic fields behave. These types of models are very helpful when we study stars outside our Solar System, since direct observations of magnetic fields can only be done for stars close to us, or more precisely, one star close to us—the Sun.

Through the development of their 3D simulation, the astronomers revealed a precise connection between the magnetic field of a star and its internal motion. This means that by tracking the internal rotation of a star, they can also determine how the magnetic field will behave. They simulated the rotation and flow of material for multiple Sun-like stars and created “internal rotation profiles”—how the insides of the stars move and convect—revealing an inverse relationship between the rotation period and the magnetic cycle period. In short, the faster the star rotates, the shorter its magnetic cycle.

Many observation programs have already provided data on Sun-type stars, so astronomers will be able to refine this model even more by applying it to this library of existing observations. Having a clearly defined relationship to work with can help in future spacecraft missions as well, by helping predict magnetic behavior, including the ESA’s Cosmic Vision Solar Orbiter and PLATO, both set to launch within the next decade.