Watch Baby Stars Blow Bubbles From Their Cosmic Nursery In This Stellar Simulation

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The world's most powerful supercomputer dedicated to astronomy simulations was recently used to simulate the formation of a cluster of baby stars. Astronomers at the National Astronomical Observatory of Japan (NAOJ) developed the new code in order to accurately simulate how clusters of baby stars form and evolve, aiding in understanding how bubbles of ionized gas are created away from the center of a galaxy.

A team of researchers at NAOJ spent two years creating a code that can accurately reproduce the motions of individual stars. The team, led by Michiko Fujii at the University of Tokyo, then simulated a comparison with the well-known Orion Nebula utilizing the supercomputer ATERUI II operated by the NAOJ. The comparison shows that its off-center bubble of ionized gas was created by an enormous star that was pushed out of the newborn cluster, but is now falling back in.

As groups of stars form together in clouds of cold hydrogen gas, the brightest and most massive stars will ionize the surrounding gas. This makes it too hot in order to form new stars. The role of these massive stars are important for understanding the overall process of star formation, according to a post on the NAOJ website.

However, in cases such as the Orion Nebula, the ionized bubble is not centered on the largest stars in the cluster. For this to occur, ionizing light from the colossal stars in the cluster must surmount the dense molecular gas in the cluster center and reach the edge of the cluster. One thought of how this happens is that scattered massive stars can "punch a hole in the dense molecular gas in the central region to help off-center ionized bubbles get started."

"The velocity of distribution of the stars in the simulation matches the result from observations," remarked Yoshito Shimajiri, a research member at NAOJ. He continued, "The simulation shows that massive, bright, young stars can be ejected from the cluster through gravitational interactions with other stars."

Once these massive stars are kicked out of their nursery cluster, they can then punch through the dense molecular cloud, while only partially ionizing the gas and still allowing for star formation to continue. It all comes down to how big of a kick the star receives.

"Some of these ejected stars run away, never to return," commented Kohei Hattori, another NAOJ researcher who helped with the project. "In other cases, like what is observed in the Orion Nebula, a massive star can be thrown a distance from the cluster, where it initiates an ionized bubble, and then fall back into the cluster."

The researchers believe the bubble-blowing ejection for the Orion Nebula likely occurred around 100,000 to 200,000 years ago.

"This simulation is not the limit of our simulation code," added Fujii. "Next we want to undertake the first star-by-star-cluster formation simulation of globular clusters, which are 100 times more massive than the star cluster we simulated in this study."

Top Image Credit: Michiko Fujii, Takaaki Takeda, 4D2U Project, NAOJ