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This finding comes from a study published in Science Advances, led by researchers at The University of Texas at Austin.

Using data from the composition of Martian meteorites, the researchers ran more than 40 computer simulations with varied temperatures, concentrations, and chemistry to estimate how much carbon, nitrogen, and sulfide gases may have been emitted on early Mars.

Instead of the high concentrations of sulfur dioxide (SO2) that previous Mars climate models predicted, their research shows volcanic activity on Mars around 3-4 billion years ago may have led to high concentrations of a range of chemically “reduced” forms of sulfur – which are highly reactive. This includes sodium sulfide (H2S), disulfur (S2) and possibly sulfur hexafluoride (SF₆) – an extremely potent greenhouse gas.

According to lead author Lucia Bellino, a doctoral student at the UT Jackson School of Geosciences, this may have made for a unique Martian environment – one that may have been hospitable to certain forms of life.

“The presence of reduced sulfur may have induced a hazy environment which led to the formation of greenhouse gases, such as SF_6, that trap heat and liquid water,” said Bellino. “The degassed sulfur species and redox conditions are also found in hydrothermal systems on Earth that sustain diverse microbial life.”

Previous Mars studies have researched how the release of gases at the surface, often through volcanic eruptions, may have impacted the planet’s atmosphere. In contrast, this study simulated how sulfur changed as it moved throughout geologic processes, including how it separated from other minerals as it was incorporated into magma layers below the planet’s crust. This is important because it gives a more realistic sense of the chemical state of the gas before it’s released at the surface where it can shape the early climate conditions of Mars.

The study also revealed that sulfur may have been frequently changing forms. While Martian meteorites have high concentrations of reduced sulfur, the Martian surface contains sulfur that’s chemically bonded to oxygen.

“This indicates that sulfur cycling – the transition of sulfur to different forms – may have been a dominant process occurring on early Mars,” said Bellino.

Last year, while the team was in the midst of its research, NASA made a discovery that seemed to back their findings. NASA’s Curiosity Mars rover rolled over and cracked open a rock, revealing elemental sulfur. While Mars is known for being rich in sulfurous minerals, it was the first time the mineral had been found in pure form, unbound to oxygen.

“We were very excited to see the news from NASA and a large outcrop of elemental sulfur,” said Chenguang Sun, Bellino’s advisor and an assistant professor at the Jackson School’s Department of Earth and Planetary Sciences. “One of the key takeaways from our research is that as S2 was emitted, it would precipitate as elemental sulfur. When we started working on this project, there were no such known observations.”

As the team moves forward, they will use their computer simulations to investigate other processes that would have been essential to sustain life on Mars, including the source of water on early Mars, and whether volcanic activity could have provided a large reservoir of water on the planet’s surface. They also seek to understand whether the reduced forms of sulfur may have served as a food source for microbes in an early climate that resembled Earth’s hydrothermal systems.

Mars is far from the Sun, and today, it’s typically cold with an average temperature of -80 degrees Fahrenheit. Bellino hopes that climate modeling experts can use her team’s research to predict how warm the early Mars climate might have been, and, if microbes were present, how long they could have existed in a warmer atmosphere.

The research was funded by The University of Texas at Austin Center for Planetary Systems Habitability, the National Science Foundation, and the Heising-Simons Foundation

Stars may look calm and peaceful in the night sky, but deep inside, they are chaotic powerhouses headed for disaster. One of the best examples of this cosmic violence is a star exploding about 11,300 years ago. Its light reached Earth in the 1660s, and what it left behind is still illuminating scientists’ understanding of how stars die.

Cassiopeia A, (Cas A) is a supernova remnant – basically, the glowing wreckage of a once-massive star. New X-ray observations with NASA’s Chandra telescope are uncovering never-before-seen secrets about the final hours before it blew apart.

Peeking inside a dying star

Before Cas A exploded, it was huge – about 15 to 20 times the mass of our Sun, maybe even more. Most likely, it was a red supergiant. But some researchers think it may have gone through a late phase as a Wolf-Rayet star, an extremely hot type of star that blows off its outer layers.

All stars eventually run out of fuel. For massive stars, this ending isn’t quiet. They go through a process called core collapse. At their center, they begin building heavier and heavier elements – first hydrogen, then helium, carbon, oxygen, and so on – until they reach iron. That’s where everything falls apart.

Iron is the dead end of a star’s fusion life. Fusing iron doesn’t produce energy – it eats it up. So once iron builds up in the core, gravity takes over. The core collapses. The outer layers crash in, then rebound in a huge explosion: a supernova.

Chandra captures star’s last moments

Over the years, scientists have studied Cas A using different types of light – radio, infrared, visible, and X-ray. But Chandra’s latest data gave researchers something brand new.

“It seems like each time we closely look at Chandra data of Cas A, we learn something new and exciting,” said lead author Toshiki Sato of Meiji University in Japan. “Now we’ve taken that invaluable X-ray data, combined it with powerful computer models, and found something extraordinary.”

That “something extraordinary” was what happened inside the star just hours before it exploded.

“We know the explosion marks the beginning of our intense observations, but what about the moments right before that?” Sato and his team wanted answers to a question few could even ask until recently.

Layers collide in an exploding star

Stars like Cas A have layers, much like an onion. The outermost layers are made of hydrogen, with heavier elements such as helium, carbon, neon, oxygen, and silicon in deeper shells. In its final hours, something dramatic happened inside Cas A.

“Our research shows that just before the star in Cas A collapsed, part of an inner layer with large amounts of silicon traveled outward and broke into a neighboring layer rich in neon,” said study co-author Kai Matsunaga. “This is a violent event in which the barrier between these two layers disappears.”

Normally, the layers stay separate. But in Cas A, silicon and neon collided. Silicon pushed outward while neon was drawn inward. The two mixed, though not completely. Instead, they formed small neighboring patches – one enriched with silicon, the other with neon.

This event is called a shell merger. It is like the star’s final gasp – its last effort to balance itself – before everything came apart.

“In the violent convective layer created by the shell merger, neon, which is abundant in the stellar oxygen-rich layer, is burned as it is pulled inward, while silicon, which is synthesized inside, is transported outward,” the researchers wrote.

The new data showed that silicon and neon did not mix with other elements either before or immediately after the explosion. The mix was uneven, creating what scientists call an “asymmetry” inside the star.

A lopsided blast reshapes science

For years, people thought exploding stars were in neat, symmetrical blasts. It made sense – gravity pulls everything in evenly, so it should collapse and explode the same way. But Chandra’s view of Cas A says otherwise.

“The coexistence of compact ejecta regions in both the ‘O-/Ne-rich’ and ‘O-/Si-rich’ regimes implies that the merger did not fully homogenize the O-rich layer prior to collapse, leaving behind multiscale compositional inhomogeneities and asymmetric velocity fields,” said the researchers.

This lopsided explosion could explain a few mysteries. For one, it may help us understand why neutron stars – the dense leftovers from supernovae – sometimes get blasted away from the explosion at high speeds. It might also show how the explosion gets triggered in the first place.

“Perhaps the most important effect of this change in the star’s structure is that it may have helped trigger the explosion itself,” said study co-author Hiroyuki Uchida. “Such final internal activity of a star may change its fate – whether it will shine as a supernova or not.”

Final chaos leaves lasting lessons

We’ve never caught a star in the act of collapsing and exploding. They’re too far, and it happens too fast. But Cas A’s wreckage is helping scientists reverse-engineer what happened.

“For a long time in the history of astronomy, it has been a dream to study the internal structure of stars,” the experts wrote.

By combining high-resolution X-ray images with powerful computer simulations, they did just that. The findings show that a star’s final moments aren’t just a calm fade-out. They’re full of chaos – burning shells crashing into each other, layers tearing apart, and violent flows of material.

“This moment not only has a significant impact on the fate of a star, but also creates a more asymmetric supernova explosion,” they wrote.

Cassiopeia A may have exploded over three centuries ago, but it’s still teaching us about the brutal beauty of stellar death. And thanks to telescopes like Chandra, we’re finally seeing what’s behind the curtain.

The full study was published in the journal The Astrophysical Journal.

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