First Rocky Planets May Have Formed 100 Million Years After Big Bang
- According to new computer simulations reported on August 19, in Astrophysical Journal Letters, the universe may have begun building rocky planets as early as 100 million years after...
- For a long time, scientists assumed that rocky planets could not exist in the early universe because the primitive expanse was dominated mostly by hydrogen and helium.
- The simulations specifically tracked a powerful type of stellar explosion known as a pair instability supernova.
According to new computer simulations reported on August 19, in Astrophysical Journal Letters, the universe may have begun building rocky planets as early as 100 million years after the Big Bang. Researchers found that debris fields from the explosive deaths of the cosmos’s first massive stars created isolated pockets of space rich enough in heavy elements to form Earth-sized worlds.
Early Planet Formation in the Primitive Cosmos
For a long time, scientists assumed that rocky planets could not exist in the early universe because the primitive expanse was dominated mostly by hydrogen and helium. Building planets requires heavier elements like iron, carbon, and silicon, which must be forged inside stars and scattered across space when those stars die. Earlier attempts to understand the timing of planetary origins used large-scale simulations to ask when the universe as a whole had accumulated enough heavy elements. However, a research team led by astronomer Daniel Whalen of the University of Portsmouth in England decided to examine the most element-enriched regions of the early cosmos. The team focused on the debris fields left behind after the universe’s first giant stars exploded. These regions possessed much higher concentrations of heavy elements than the global average, acting similarly to ash-rich clearings left by forest fires where nutrients are suddenly concentrated.
The Role of Pair Instability Supernovas
The simulations specifically tracked a powerful type of stellar explosion known as a pair instability supernova. These cataclysms mark the death throes of extremely massive stars that can create a hundred times the mass of the sun in heavy elements alone. Whalen and his colleagues monitored the evolution of this debris as it expanded, cooled, and mixed with surrounding gas in the early universe. Over time, gravity pulled portions of that material together, causing it to collapse into a small new star surrounded by a swirling, dusty disk. Within that disk, the computer simulation revealed the formation of planetesimals—small rocky bodies ranging from a few meters to a few kilometers across that serve as the embryonic seeds of planets.
Habitable Zones and Water in the Early Universe
The findings indicate that these debris fields produced enough rocky material to potentially build several Earth-sized worlds. Furthermore, the simulation showed that water was available in the young stellar system and could have reached a planet later on. Some of these planetesimals even formed at distances from their young star capable of supporting liquid water on their surfaces. This region, known as the habitable zone, provides conditions where temperatures are neither too hot nor too cold for liquid water to exist, pushing the potential timeline for planetary habitability far earlier than previously thought possible.