How violent flares from the young Sun changed Earth forever

An international team of astronomers has witnessed a dramatic, multi-layered burst of magnetized plasma from EK Draconis, a young star often seen as a twin of our early Sun.

The hottest material raced at up to 550 kilometers per second, tracked by Hubble and synchronized telescopes in Japan and Korea.

Solar storms shape planets

Kosuke Namekata of Kyoto University led the coordinated observing campaign using both space- and ground-based telescopes.

Coronal mass ejections (CMEs) – massive bursts of magnetized plasma launched from a star – have the power to reshape the environments of surrounding planets.

“What inspired us most was the long standing mystery of how the young Sun’s violent activity influenced the nascent Earth,” said Namekata.

The Sun’s twin star

EK Draconis is a solar analogue, a star similar to the Sun in mass and temperature. Its youth and activity offer a window into how our own star behaved more than four billion years ago.

CMEs inject energy and particles into space weather that sometimes shake Earth’s magnetosphere, the region dominated by Earth’s magnetic field.

The same physics, scaled up on a younger star, can push atmospheres around and change their chemistry.

How scientists tracked the eruption

The team used far-ultraviolet light -wavelengths shorter than 200 nanometers – to observe the star’s scorching hot gas.

At the same time, ground-based spectrographs monitored the hydrogen-alpha line, revealing cooler material moving in the eruption.

We can see motion by measuring a Doppler shift, a wavelength change caused by motion along our line of sight. In these spectra, material moving toward us shows up as a slight blue shift that grows with speed.

By synchronizing a spacecraft with three ground observatories, the team was able to track the outflow continuously during the crucial minutes of the eruption.

This approach minimized interference from other flare-related motions that could have obscured the true ejection signal.

With both wavelength bands available, the researchers could clearly distinguish the hot and cool layers instead of relying on a single spectral line for inference. This distinction forms the basis for their conclusions about the structure of the ejected material.

The complex eruption of EK Draconis

Just before and during a bright flare, gas heated to about 100,000 kelvin blasted outward at speeds between 300 and 550 kilometers per second.

These velocities were detected through blueshifted far-ultraviolet lines that trace the star’s upper atmospheric gas.

Roughly ten minutes later, a cooler filament around 10,000 kelvin drifted outward at 70 kilometers per second. A filament, a cool dense strand held aloft by magnetic fields, leaves a blue-shaded bite in the hydrogen alpha line.

The cool absorption persisted for nearly two hours while the hot signature faded quickly from the ultraviolet lines. The timing and different speeds argue that the two signals came from different layers of the same event.

Overall, the observations reveal an ejection with multiple temperature layers, not a single uniform blob merely slowing as it ascends.

This layered structure aligns with how solar scientists describe coronal mass ejections – dense cores surrounded by faster, hotter outer shells.

Hot layers powered the blast

Hot layers usually move faster and carry more kinetic energy than cool layers. That imbalance helps drive shocks and energetic particles that can change the tops of atmospheres.

Earlier work on this same star caught only a cool filament after a superflare. Adding far ultraviolet data fills in the missing warm component, which explains the energy carried away.

The patterns here fit two possibilities: a layered CME or a chain of linked eruptions called a sympathetic sequence. A sympathetic eruption, an event triggered by a nearby eruption through magnetic links, could explain the short delay.

In either case, the warmer material likely provided most of the driving force, while the cooler filament represented the denser core of the ejection.

This distinction is crucial, since both atmospheric chemistry and escape depend on the energy and timing of the incoming material.

Solar storms build atmospheres

When shocks from frequent CMEs accelerate high energy particles, they can make greenhouse gases and precursors of life’s building blocks.

Prebiotic chemistry, reactions that create biological molecules before life exists, is one probable outcome in such conditions.

Those particles can also compress a planet’s magnetosphere, the bubble controlled by its magnetic field, and open wider polar caps. That expansion gives particles easier access to thicker air where they can trigger more reactions.

Energy from a violent young Sun

In thicker air, ionization can help produce nitrous oxide and hydrogen cyanide, both central to temperature control and molecular assembly.

Models imply that a stormy young Sun could have supplied enough particle energy to sustain these pathways.

For exoplanets around active Sun-like stars, this mechanism is a double-edged factor for habitability. It can erode unprotected air but may also create molecules that make surfaces warmer and more chemically ready.

Future studies of EK Draconis

Catching both hot and cool layers required tight timing that few campaigns have achieved. Repeating these synchronized observations will reveal whether layered CMEs are the rule rather than the exception.

Future ultraviolet missions and existing ground spectrographs can build catalogs of eruptions across ages and stellar types. Those catalogs will test how often minor flares carry ejections that matter for planets.

Refined measurements of these rates and energies feed directly into climate models for early Earth and for the exoplanets scientists are just beginning to explore.

They also guide where and how to search for atmospheric biosignatures around young, Sun-like stars.

For now, EK Draconis offers a vivid glimpse of how a restless young star can sculpt the worlds around it – a glimpse that brings us closer to understanding how our own solar system evolved as life was taking its first steps.

The study is published in the journal Nature Astronomy.

Image Credit: NAOJ

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