How magnetic field influences star formation

A new study has provided a deeper insight into how the magnetic field influences star formation on a variety of scales, from hundreds of light-years down to a fraction of a light-year.

Stars form when gravity pulls together material within giant clouds of gas and dust. But gravity isn't the only force at work. Both turbulence and magnetic fields battle gravity, either by stirring things up or by channeling and restricting gas flows, respectively.

The study probed the Cat's Paw Nebula, also known as NGC 6334. This nebula contained about 200,000 suns' worth of material that is coalescing to form new stars, some with up to 30 to 40 times as much mass as our sun. It's located 5,500 light-years from Earth in the constellation Scorpius.

Hua-bai Li (The Chinese University of Hong Kong) said that the magnetic field direction was quite well preserved from large to small scales, implying that self-gravity and cloud turbulence were not able to significantly alter the field direction.

The team observed polarized light coming from dust within the nebula using several facilities, including the Smithsonian's Submillimeter Array.

Because dust grains align themselves with the magnetic field, the researchers were able to use dust emission to measure the field's geometry. They found that the magnetic fields tended to line up in the same direction, even though the relative size scales they examined were different by orders of magnitude. The magnetic fields only became misaligned on the smallest scales in cases where strong feedback from newly formed stars created other motions.

This work represents the first time magnetic fields in a single region have been measured at so many different scales. It also has interesting implications for the history of Earth's galaxy.

The study is published in the journal Nature.