Astronomers have taken a close look at the magnetic activity of a young star strikingly similar to our own sun—and discovered that it has a magnetic cycle running nearly ten times faster.
The star, called Iota Horologii (ι Hor), completes a full flip of its magnetic poles in just over two years, compared with the sun’s familiar 22-year cycle.
The findings come from scientists at the Leibniz Institute for Astrophysics Potsdam (AIP) as part of their “Far Beyond the Sun” campaign, which aims to understand how stars like the sun generate and evolve their magnetic fields.
The team used nearly three years of detailed observations collected with the HARPS polarimeter at the European Southern Observatory’s 3.6-meter telescope in Chile.
ι Hor is located about 56 light years from Earth in the southern constellation Horologium, the “pendulum clock.”
At just 600 million years old, it is much younger than our 4.6-billion-year-old sun. That youth makes it spin faster and behave more energetically, with intense magnetic activity compared to the relatively calm solar surface we are used to.
To study it, the researchers used a technique called Zeeman Doppler Imaging (ZDI). This method allowed them to turn 199 nights of spectropolarimetric data into 18 “maps” of the star’s magnetic field, covering about 140 full rotations.
These maps revealed how magnetic regions form, disappear, and even switch polarity, offering an inside look at the star’s powerful dynamo—the mechanism deep within its interior that generates magnetic fields.
One of the biggest surprises was the speed of ι Hor’s cycle. Its magnetic poles flip and reset every 773 days, producing a rapid “heartbeat” compared with the sun’s much slower pace.
To visualize this, the team also created the first magnetic “butterfly diagrams” for a star beyond our solar system. On the sun, these diagrams show how sunspots migrate across latitudes during each cycle. For ι Hor, the researchers found similar migrations, but at far faster speeds.
Magnetic regions on the star were seen drifting toward the poles at up to 78 meters per second, while other fields moved toward the equator at up to 19 meters per second.
For comparison, those speeds are like watching magnetic features travel as fast as a train or a car across the star’s surface. This is the first time such flows have been measured directly on a star other than the sun.
“These results give us a benchmark for how stellar dynamos work,” said Dr. Julian Alvarado Gómez, lead investigator at AIP. By comparing the rapid cycle of ι Hor with the sun’s slower rhythm, astronomers can better understand how age and rotation shape magnetic activity.
The implications extend beyond stellar physics. Magnetic activity drives stellar winds, flares, and bursts of radiation—phenomena that can dramatically affect the atmospheres and habitability of surrounding planets.
Since ι Hor is known to host at least one exoplanet, its magnetic fireworks may offer a glimpse of what young Earth-like worlds endure as their suns grow older and calmer.
Source: KSR.
