Context:
Astronomers may be closer to solving one of science’s oldest mysteries: how did water originate in the universe? A groundbreaking study published in Nature Astronomy on March 3 suggests that the universe’s earliest stars produced water through colossal supernova explosions, challenging existing theories and potentially reshaping our understanding of life’s earliest possibilities.
The Birth of the First Stars
- Water’s cosmic presence: Water is the third most abundant molecule in the universe after hydrogen and carbon monoxide, yet its origins have remained uncertain.
- The Big Bang aftermath: About 13.8 billion years ago, the Big Bang formed all matter, and the first stars emerged a few hundred million years later, composed solely of hydrogen and helium.
- Star evolution: These massive stars eventually exhausted their hydrogen fuel and exploded as supernovae, setting the stage for new star formations.
Star Populations Explained
- Population I stars: Youngest, metal-rich stars like our Sun.
- Population II stars: Older, with lower metallicity.
- Population III stars: The universe’s first generation of stars, massive and composed entirely of hydrogen and helium. According to the new study, these stars could have been the first creators of cosmic water.
3D Simulations and Key Discoveries
- Research approach: Led by astronomer D.H. Whalen from the University of Portsmouth, the team used advanced 3D simulations to study Population III supernovae.
- Findings: Conditions for water formation existed between 50 million and 1 billion years after the Big Bang. Supernovae from these gigantic stars expelled oxygen, which combined with hydrogen to form water — a vital ingredient for life.
The Infant Universe and Abundant Water
- Accelerated water formation: The research suggests that early supernovae produced more water than previously believed, implying that planets with water could have formed much earlier in cosmic history.
- Potential for early life: This discovery shifts the timeline for the possibility of life in the universe to billions of years earlier than assumed.
Addressing Limitations
- Observational challenges: Population III stars are too distant to be observed directly, relying on simulation models.
- Confidence in the model: Whalen stated that their models accurately reflect ionising UV radiation and gas dynamics based on well-established stellar evolution theories.
This study revolutionizes our understanding of water’s origins, suggesting that life-supporting conditions may have existed far earlier than previously imagined. If proven, it could drastically reshape theories on planetary formation and the timeline for life’s emergence in the cosmos.
Source: TH
