A Nearby Star’s Eruption Could Spell Bad News For the Future of Life on Earth

A Rundown on The Sun:

Our Sun is classified as a main-sequence yellow dwarf (G2V) star. It’s currently about halfway through its estimated 10 billion-year lifespan, which means it is roughly 4.6 billion years old, and as far as stars go, it’s pretty boring and predictable. It’s not a red dwarf — a type of star with so little mass and burns so slowly that it might outlive the universe itself — or a hypergiant — the most significant, energetic, and unpredictable type of star. It’s right in between, which is a good thing for us, as it means stars like ours are stable enough for planets in the so-called Goldilocks zone where temperatures are not too hot or cold for the evolution of human-like life to occur. 

Inside the Sun’s core, it is extremely hot, roughly believed to reach temperatures exceeding  27,000,000 degrees Fahrenheit (or 15,000,000 degrees Celsius). The temperatures are hot enough, and the Sun is massive enough to sustain the process of nuclear fusion within the core. Therefore, it fuses lighter elements, such as hydrogen, into heavier elements, up to and including oxygen — a critical element that plays a singular role in our continued existence here on Earth. 

As previously reported, “The energy produced in the core powers the Sun and produces the heat, light, and radiation the Sun emits. This energy is also important in keeping the balance between the Sun and the intense gravitational pull exerted in the Sun’s core. One day, there won’t be enough energy to counteract the gravitational pull, so the Sun will eventually contract — increasing both the pressure and temperature of the Sun’s core. As the amount of helium builds up in the core, the temperature of the fusion reactions will increase to counteract the increasing density, which is the beginning of the end.”

“This extra energy will result in the Sun first growing brighter, and then the outer layers will swell up, whereby the Sun’s atmosphere will increase to something like 200 times its current size, creating a red giant and putting it right in Earth’s path.”

In the middle of all that gas shed off into space will be an object roughly the size of Earth but with approximately half the Sun’s mass, known as a white dwarf. These objects are extremely luminous and compact but not conducive to enabling life on nearby planets… at least not in the inner solar system. For a brief time, the frozen wastelands in the outer solar system — such as Europa and Titan — may become habitable, but life on Earth, if Earth isn’t already swallowed up by the expanding Sun, that is, would be toast. 

Ch-Ch-Ch Changes

We know it will be a long time until the Sun swallows Earth, but that doesn’t mean Earth won’t be affected by the Sun’s behavior as the star ages. One star scientists are studying to glimpse our Sun’s past, present, and future is a star located approximately 111 light-years from Earth, known as EK Draconis (after the Draco constellation it resides on the border of). It’s a G-type yellow dwarf star, just like the Sun. Estimations of its age vary. While some estimates suggest it’s older than the Sun, most put it between 50 and 150 million years old — which, if true would give us a glimpse at how the Sun may have looked 4.5 billion years ago. Despite the age discrepancy, it checks off all the boxes for being considered a Sun-like star. Looking back through time and peering at the star allows us to see how the Sun might have behaved when it was still in its infancy. 

A new paper suggests main-sequence stars like our Sun and EK Draconis may not be as stable as we previously thought. The report describes what an international team of astronomers observed coming from EK Draconis: a substantial coronal mass ejection significantly bigger than anything our Sun has ever been known to churn out. 

What are coronal mass ejections (CMEs), you might be asking? They are incredibly energetic bursts of highly magnetized plasma and radiation that occur due to instabilities in the Sun’s massive magnetic field. They are capable of ejecting “flares” that release what would be equivalent energy to 20 million nuclear bombs within moments. 

When one occurs, it’s believed that scorching gases, known as plasma, bubble up and become all twisted out of shape when the Sun’s magnetic field gets “kinks” in it. Ultimately, these superheated gases, which contain massive amounts of charged particles, are shed in the billions of tons from the surface of the Sun. Additionally, the bubbles of gaseous material can travel at speeds as slow as 250 kilometers per second (km/s) to as fast as nearly 3000 km/s. Sometimes this phenomenon can occur several times a day; sometimes — when the Sun isn’t exhibiting much activity — one forms every 5 days. 

It’s semi-rare for a stream of charged particles to hit Earth head-on, but when it does actually happen, it can ignite geomagnetic storms that affect our space-based instruments and tools. According to EarthSky, “The shock wave of charged particles compresses the Earth’s dayside magnetic field while the nightside gets stretched out. Like an elongated rubber band, the terrestrial magnetic field eventually snaps back with the same energy as a lightning bolt.”

“The onslaught of charged particles and the temporary restructuring of the Earth’s magnetic field has observable effects. Auroral lights, usually only seen near the poles, can drift to lower latitudes and become more brilliant. The disturbance of the magnetic field can also expose Earth to deadly cosmic rays. The atmosphere still provides enough protection for everyone on the ground. But astronauts in space may receive lethal doses of radiation. During a solar storm in 1989, cosmonauts aboard the Mir space station received their maximum yearly radiation dose in just a few hours!”

So What Was Observed on EK Draconis? 

The paper, published in the December 9 issue of the journal Nature Astronomy, is the culmination of more than 32 nights of observation between the winter and spring of 2020. Astronomers from the University of Colorado aimed two satellites — NASA’s Transiting Exoplanet Survey Satellite (TESS) and Kyoto University’s SEIMEI Telescope — at the star system in hopes of witnessing a CME and witnessing a CME; they did!

On April 5th of, 2020, the star was noted as having generated a superflare. Just half an hour later, a genuinely spectacular CME was spotted spewing from the star’s surface at speeds exceeding 994,194 miles (1.6 million kilometers) an hour, making it roughly ten times larger and more potent than any CME we’ve ever seen come from a Sun-like star ever before.

The press release notes, “Recent research, however, has suggested that this sequence of events on the sun may be relatively sedate, at least so far as scientists have observed. In 2019, for example, Notsu and his colleagues published a study that showed that young sun-like stars around the galaxy seem to experience frequent superflares — like our own solar flares but tens or even hundreds of times more powerful.”

“Such a superflare could, theoretically, also happen on Earth’s sun but not very often, maybe once every several thousand years. Still, it got Notsu’s team curious: Could a superflare also lead to an equally super coronal mass ejection?”

“Superflares are much bigger than the flares that we see from the sun,” Notsu said. “So we suspect that they would also produce much bigger mass ejections. But until recently, that was just conjecture.”

“It may also not bode well for life on Earth: The team’s findings hint that the sun could also be capable of such violent extremes. But don’t hold your breath — like superflares, super coronal mass ejections are probably rare around our getting-on-in-years sun.”

“Still, Notsu noted that huge mass ejections may have been much more common in the early years of the solar system. Gigantic coronal mass ejections, in other words, could have helped to shape planets like Earth and Mars into what they look like today.”

“The atmosphere of present-day Mars is very thin compared to Earth’s,” Notsu said. “In the past, we think that Mars had a much thicker atmosphere. Coronal mass ejections may help us to understand what happened to the planet over billions of years.”