The most realistic three-dimensional simulator of the birth of stars has been released. Besides being useful for astrophysicists seeking to understand this crucial process, it's a treat for everyone to watch.
Star formation takes place so slowly the few decades since our telescopes could watch the process have seen insignificant change. “When we observe stars forming in any given region, all we see are star formation sites frozen in time,” Dr Michael Grudić of Northwestern University said in a statement. “Stars also form in clouds of dust, so they are mostly hidden.”
Instead, what we know comes from seeing many stars at different stages of the process. Simulations have operated either at low resolution or left out some factors we suspect are important.
STARFORGE (Star Formation in Gaseous Environments) aims to change that, simulating developing stars in a realistic context, rather than in isolation, but it's still not quick. Using one of the world's most powerful supercomputers, STARFORGE takes up to three months to run a single simulation.
Few stars form on their own, instead having their origins in clusters, which often include hundreds of other stars of similar ages. The largest of these evolve so fast they can become supernovas before the last stars in the cluster form, shaping their births. Even stars that don't get that far can still produce powerful stellar winds that influence everything around them.
“Other models have only been able to simulate a tiny patch of the cloud where stars form — not the entire cloud in high resolution. Without seeing the big picture, we miss a lot of factors that might influence the star’s outcome,” Grudić said.
Wait for the end credits
Besides the beautiful images, STARFORGE has already paid off scientifically. A paper published three months ago in the Monthly Notices of the Royal Astronomical Society reveals a previously unconfirmed role for protostellar jets in determining a star's starting mass. When these jets were left out of the simulation the team ended up with a distribution of stars that included far too many giants compared to what we actually see. The inclusion of the jets produced much more realistic outcomes. The effects are most noticeable when modeling smaller gas clouds.
“Jets disrupt the inflow of gas toward the star,”Grudić said. “They essentially blow away gas that would have ended up in the star and increased its mass. People have suspected this might be happening, but, by simulating the entire system, we have a robust understanding of how it works.”
Since initial mass is the most important factor in determining a star's fate, the discovery is an important insight into why stars are so different from each other. “Knowing the mass of a star tells us its brightness as well as what kinds of nuclear reactions are happening inside it,” said co-creator Dr Claude-André Faucher-Giguère. “With that, we can learn more about the elements that are synthesized in stars, like carbon and oxygen — elements that we are also made of.”
A description of how STARFORGE works and its potential has been published in Monthly Notices of the Royal Astronomical Society.