Molecular clouds prolong their lives by constantly reassembling themselves
(ORDO NEWS) — Astronomers have recently discovered that giant clouds of molecular hydrogen can exist for tens of millions of years, despite the fact that individual molecules are constantly being broken down and reassembled.
This new research helps make important contributions to our overall picture of how stars are born.
Recent observations have shown that when new stars emerge inside a giant molecular cloud, they rapidly blow out the bubbles surrounding them.
The remaining molecules are bombarded with ionizing radiation, which splits molecular hydrogen into an ionized state.
But according to other studies, these giant clouds have been around for an incredibly long time. So how can this be if newborn stars are constantly tearing apart their parent clouds?
The research team turned to sophisticated computer simulations to answer this question. The scientists modeled part of the galaxy and studied the behavior of molecular clouds as stars formed in them.
They found that the simulations are consistent with observations: newborn stars can easily break apart a molecular cloud. But the researchers also found a balancing factor.
Giant molecular clouds are constantly evacuating any surrounding hydrogen that wanders randomly through the galaxy. This accumulation action replenishes the hydrogen in the cloud.
Scientists have found that individual molecular clouds can live up to almost 100 million years. But any single hydrogen molecule will only last up to four million years in this cloud before it separates.
However, in place of each evaporating molecule, a new one comes into the cloud, maintaining the balance. As long as the cloud can continue to accumulate material, it will live.
These results explain how giant molecular clouds can exist for so long despite the disappearance of individual molecules.
And because these giant molecular clouds are the birthplaces of stars, this research helps paint a picture of how galaxies can continue to produce stars for billions of years.
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