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New study shows how the smallest galaxies produce stars

The Phoenix dwarf galaxy is one of the few dwarf galaxies capable of generating new stars. Photo by European Southern Observatory
The Phoenix dwarf galaxy is one of the few dwarf galaxies capable of generating new stars. Photo by European Southern Observatory

Aug. 12 (UPI) -- Astronomers finally have an explanation for how some of the cosmos' smallest galaxies make new stars.

Dwarf galaxies don't typically host as many stars as larger galaxies like the Milky Way, but they're no lightweights either -- some have outsized stellar populations.

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Now, a study published Wednesday in the Monthly Notices of the Royal Astronomical Society suggests a few of the universe's smallest galaxies are able to resume stellar production after billions of years of dormancy.

"It is estimated that these dwarf galaxies stopped forming stars around 12 billion years ago," lead researcher Martin Rey, an astrophysicist at Lund University in Sweden, said in a news release. "Our study shows that this can be a temporary hiatus."

New high-resolution computer models suggest heating and ionization triggered by the energy of newborn stars halts stellar production inside dwarf galaxies.

The simulations, however, also showed that star formation can resume after a prolonged hiatus.

"Our simulations show that dwarf galaxies are able to accumulate fuel in the form of gas, which eventually condenses and gives birth to stars," Rey said. "This explains the observed star formation in existing faint dwarf galaxies, which has long puzzled astronomers."

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The new research was time-consuming and energy-intensive, researchers said, with each simulation running on 40 laptops for up to two months.

The modeling effort showed that while most dwarf galaxies remain permanently dormant, a few are able to accumulate enough mass to reignite star formation.

"By deepening our understanding of this subject, we gain new insights into the modeling of astrophysical processes such as star explosions, as well as the heating and cooling of cosmic gas," Rey said.

"In addition, further work is underway to predict how many such star-forming dwarfs exist in our Universe, and could be discovered by astronomical telescopes," he said.

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