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Astronomers discover star with a powerful magnetic field and an activity cycle 10 times faster than our Sun’s

The intricate magnetic lifecycle of Iota Horologii (ι Hor), a 600-million-year-old Sun-like star, was successfully mapped by scientists at the Leibniz Institute for Astrophysics Potsdam.

BY RAJ NAIK

PUBLISHED OCT 13, 2025

This artist's concept illustrates a young, red dwarf star surrounded by three planets. Such stars are dimmer and smaller than yellow stars like our sun (Representative Cover Image Source: NASA/JPL-Caltech)

A star remarkably similar to our Sun but far younger has revealed an extremely rapid magnetic reversal cycle, completing a full switch of its magnetic poles in less than three years, a rate nearly ten times faster than the Sun's 22-year rhythm, according to Leibniz Institute for Astrophysics Potsdam.

The varying magnetic field of the star Iota Horologii at three different times, showing a double polarity reversal (magnetic cycle) (Image Source: Leibniz Institute for Astrophysics Potsdam)

Scientists at the Leibniz Institute for Astrophysics Potsdam (AIP) have successfully charted the magnetic lifecycle of Iota Horologii (ι Hor), a 600-million-year-old star located about 56 light-years away. The full findings were published in the journal Astronomy & Astrophysics. The star, which spins and flares with significantly greater vigor than our 4.6-billion-year-old Sun, provides an unprecedented window into the evolution of stellar magnetic dynamos. Using the HARPS polarimeter at the European Southern Observatory’s La Silla Observatory in Chile, researchers amassed data over six observing seasons. An advanced mapping technique, Zeeman Doppler Imaging (ZDI), converted these observations into 18 detailed magnetic field maps across 140 stellar rotations.

The very successful HARPS spectrograph, attached to ESO’s 3.6-metre telescope at La Silla, Chile, has been enhanced with a new capability: the most precise polarimeter in the world (Image Source: ESO) — The very successful HARPS spectrograph, attached to ESO’s 3.6-metre telescope at La Silla, Chile, has been enhanced with a new capability: the most precise polarimeter in the world (Image Source: ESO | F. Snik)

The most striking revelation is ι Hor's rapid magnetic heartbeat: its north and south magnetic poles completely reverse polarity and return in just 773 days (a little over two years). This hyper-fast cycle dramatically contrasts with the Sun's more sedate, decades-long reversal. Furthermore, the team created the first-ever "magnetic butterfly diagrams" for a star other than the Sun. These diagrams, which on the Sun track the migration of sunspots, for ι Hor map the movement of its magnetic regions, demonstrating how they drift poleward and equatorward during the cycle.

via GIPHY

These diagrams allowed scientists to measure the colossal surface flows driving the magnetic activity. The magnetic field regions are migrating at speeds comparable to high-speed trains (15–78 m/s) toward the poles and at average car speeds (9–19 m/s) toward the equator, flows substantially quicker than those observed on the Sun. This marks the first direct measurement of such flows on an external star.

Illustration of an extrasolar planet, a planet orbiting a star other than the Sun that is somewhat like the Earth. (Representative Photo by MARK GARLICK / SCIENCE PHOTO LIBRARY / Getty Images) — Illustration of an extrasolar planet, a planet orbiting a star other than the Sun that is somewhat like the Earth. (Representative Image Source: Getty | MARK GARLICK / SCIENCE PHOTO LIBRARY)

"These results offer a critical benchmark," stated lead investigator Dr. Julian Alvarado Gómez. “By comparing ι Hor’s rapid magnetic cycle and strong activity to the Sun’s more leisurely 22-year rhythm, we gain deeper insight into how factors like rotation rate and age influence magnetic evolution.” The star’s magnetic activity governs phenomena like powerful flares and stellar winds, which can dramatically influence the atmosphere and surface conditions of orbiting planets. Given that ι Hor hosts at least one known exoplanet, the findings are vital for assessing the habitability of worlds around young, Sun-like stars.

Artist’s impression of the closest black hole to Earth and its Sun-like companion star (Cover Image Source: International Gemini Observatory) — Artist’s impression of the closest black hole to Earth and its Sun-like companion star (Representative Image Source: International Gemini Observatory)

The search for life beyond our solar system has received a significant boost. New analysis of data from NASA's retired Kepler space telescope suggests that roughly half of all stars with temperatures similar to the Sun could host a rocky planet capable of maintaining liquid water on its surface, as mentioned on NASA's official site. This finding brings humanity one step closer to answering the long-standing question of how many of the confirmed exoplanets, planets outside our solar system, might harbor life.