Molecular clouds prolong their lives by constantly reassembling themselves
(ORDO NEWS) — Astronomers recently discovered that giant clouds of molecular hydrogen, the birthplace of stars, can live for tens of millions of years as individual molecules are constantly being broken down and reassembled.
This new research helps to make an important contribution to understanding the big picture of how stars are born.
To create stars, you first need giant clouds of molecular hydrogen gas. These are reservoirs that can undergo a catastrophic collapse. In this case, dozens and even hundreds of stars can appear at once.
Stars cannot be created without reservoirs of gas, so astronomers are especially interested in how these clouds behave.
The evolution of clouds in the galactic environment can tell about the history of star formation in the galaxy.
Recent observations have shown that when new stars appear inside a giant molecular cloud, they quickly blow out the surrounding molecules.
Due to the reduced density of molecules surrounding these stars, the remaining molecules are bombarded with ionizing radiation, causing molecular hydrogen to become ionized.
But other observations have shown that giant clouds exist for an incredibly long time. So what if the newborn stars are constantly tearing apart the parent clouds?
The research team turned to sophisticated computer simulations to answer this question. They modeled part of a galaxy and examined the behavior of molecular clouds as stars form within them.
They found that their simulations are consistent with observations: newborn stars can easily tear apart a molecular cloud. But they also found a balancing factor.
Giant molecular clouds are constantly consuming any ambient hydrogen that randomly roams the galaxy. This accumulation action replenishes the hydrogen in the cloud.
The researchers found that individual molecular clouds can live up to almost 100 million years. But any single hydrogen molecule will only exist in this cloud for up to four million years before it dissociates.
But for every molecule that evaporates, a new one enters the cloud, keeping everything in balance. As long as the cloud can accumulate material, it will continue to live.
These results explain how giant molecular clouds can live for so long despite their individual molecules disappearing.
And since giant molecular clouds are the birthplace of stars, this research helps paint a picture of how galaxies can continue to produce stars for billions of years.
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