The study found that how big a star eventually grows does not depend on the size of its initial core, but is determined by how much resources it can absorb in competition with nearby objects as it develops.
This finding was unexpected by most astronomers. Scientists generally believe that a star’s original core came from at least two scenarios: one formed by the continuous clumping together of gas, or the remnants of another dead star. These cores are like the “seeds” of a new star, and they grow slowly. The larger the initial core, the larger the star that eventually grows.
But the study, published March 22 in the journal The Astrophysical Journal Letters, finds that it appears that competition with other objects as the star grows has a greater effect on the final size of the star.
The study, led by the National Astronomical Observatory of Japan (NAOJ), took a close look at the newly grown stars inside the Orion Nebula Cluster and compared them with stars that have not yet grown into new stars and have just formed cores from gas clumped together.
It turns out that the mass of the core has little effect on the size and mass of the final star, which means that how the star competes for cosmic gas resources as it grows plays a more important role in the final mass of the star.
The researchers say the next step is for them to look at data from other regions of the universe to find out if this is unique to the Orion Nebula region, or if it is a pattern commonly followed in the universe for stellar growth. If the latter is the case, it will rewrite scientists’ knowledge of the mechanisms of star birth and the interactions between stars.
In any case, the researchers also said, the study shows that future models of stellar evolution should not model them as independent individuals in a vacuum, but as part of a surrounding “community” where the cosmic environment plays an important role in influencing them.
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