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Magnetic fields play an important role in the places where most massive stars are born. This illustration shows the surroundings of a forming massive star, and the bright regions where radio signals from methanol can be found. The bright spots represent methanol masers -- natural lasers that are common in the dense environments where massive stars form -- and the curved lines represent the magnetic field. Thanks to new calculations by astrochemists, astronomers can now start to investigate magnetic fields in space by measuring the radio signals from methanol molecules in these bright sources. Credit: Wolfgang Steffen/Boy Lankhaar et al. (molecules: Wikimedia Commons/Ben Mills)

The secrets of the magnetic fields where massive stars are usually born may soon be revealed.

A team of scientists have developed a new method to measure magnetic fields in space using methanol, giving astronomers a way to investigate how massive stars are born.

Scientists have discovered many molecules in space over the last 50 years using radio telescopes to investigate what happens in the dark and dense clouds where new stars and planets are born.

Researchers can measure temperature, pressure and gas motions when they study the signature of the molecules they detect. However, it is difficult to measure magnetic fields where the most massive stars are born.

“When the biggest and heaviest stars are born, we know that magnetic fields play an important role,” Boy Lankhaar, of Chalmers University of Technology, who led the project, said in a statement. “But just how magnetic fields affect the process is a subject of debate among researchers.

“So we need ways of measuring magnetic fields, and that's a real challenge,” he added. “Now, thanks to our new calculations, we finally know how to do it with methanol.”

Methanol molecules shine brightly as natural microwave lasers (masers) on the dense gas surrounding many newborn stars. The signals measured from methanol masers are both strong and emitted at very specific frequencies.

“The maser signals also come from the regions where magnetic fields have the most to tell us about how stars form,” Wouter Vlemmings, a team member from Chalmers, said in a statement. “With our new understanding of how methanol is affected by magnetic fields, we can finally start to interpret what we see.”

Researchers have previously attempted to measure the magnetic properties of methanol in laboratory conditions, but in the new study, the scientists built a theoretical model to make sure it was consistent both with previous theory and with the laboratory measurements.

“We developed a model of how methanol behaves in magnetic fields, starting from the principles of quantum mechanics,” Lankhaar said. “Soon, we found good agreement between the theoretical calculations and the experimental data that was available.

“That gave us the confidence to extrapolate to conditions we expect in space,” he added.

However, it became a challenge to make the new calculations, while correcting previous work.

“Since methanol is a relatively simple molecule, we thought at first that the project would be easy,” theoretical chemist Ad van der Avoird of Radboud University in the Netherlands, said in a statement. “Instead, it turned out to be very complicated because we had to compute the properties of methanol in great detail.”

The results open up new possibilities for understanding magnetic fields in the universe and also show how problems can be solved in astrochemistry.

The study was published in Nature Astronomy.     

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