(ORDO NEWS) — Astronomers have developed a new model for a cluster of young stars. A comparison with a well-known real-life example of the Orion Nebula shows that its displaced bubble of ionized gas was caused by a massive star that was ejected from the newborn cluster but is now falling back.
Groups of stars often form together in clouds of cold hydrogen gas. The brightest and most massive stars ionize the surrounding gas, making it too hot for new stars to form.
Thus, massive stars act as a feedback loop, blocking the formation of new stars. The role of these massive stars is important for understanding the overall process of star formation.
But in many cases, such as in the Orion Nebula, the ionized bubble is not concentrated on the most massive stars in the cluster.
To form such off-center bubbles, ionizing light from massive stars in a cluster must overcome the dense molecular gas at the center of the cluster and reach its outskirts.
There is a possibility that scattered massive stars can punch a hole in the dense molecular gas in the central region to help the generation of dislodged ionized bubbles.
A team of researchers led by Michiko Fujii at the University of Tokyo spent two years developing a simulation code that could accurately reproduce the movements of individual stars.
They then simulated an Orion Nebula-like phenomenon using ATERUI II at the National Astronomical Observatory of Japan (NAOJ), the world‘s most powerful astronomical simulation supercomputer.
“The stellar velocity distribution in the simulations matches the observations,” explains Yoshito Shimajiri, a member of the research team at NAOJ.
“The simulations show that massive, bright, young stars can be ejected from the cluster as a result of gravitational interactions with other stars.”
Kouhei Hattori, who also worked for NAOJ and did some of the analysis, continues, “Some of these discarded stars run away, never to return. In other cases, as seen in the Orion Nebula, a massive star can be ejected away from the cluster, where it initiates an ionized bubble and then falls back into the cluster.”
Fujii comments on the future potential of the study: “This simulation is not the limit of our simulation code. If we use more processors, it will be able to handle even more massive star clusters.
Next, we want to do the first simulation of the formation of globular clusters that are 100 times more massive than the stellar cluster we modeled in this study.”
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