Coherent magnetic field discovered in the interstellar medium

(ORDO NEWS) — Magnetic fields are important, but often “secret” ingredients of the interstellar medium and elements of star formation. The veil of secrecy surrounding the magnetic fields maintained in interstellar space stems from a lack of experimental probes.

And although we know from Faraday’s experiments that the connection between electric and magnetic fields can be detected using a coil of current, astronomers cannot launch such coils into space at a distance of several light years from us.

In the new work, astronomers led by Dr. Li Di (LI Di) of the National Astronomical Observatories of the Chinese Academy of Sciences were able to accurately measure the magnitude of the magnetic field intensity in the molecular cloud L1544 – the region of space where the interstellar medium is ready to form new stars.

The team used the HI Narrow Self-Absorption (HINSA) method developed by Dr. Dee and colleagues in 2003. The high sensitivity of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) they are using in their new work has recorded the significant Zeeman effect in according to the HINSA method. As a result, the authors were able to come to the conclusion that such molecular clouds reach a supercritical state, that is, a state of complete readiness for collapse, earlier than expected in standard models.

The Zeeman effect – the splitting of spectral lines into several frequency components in the presence of a magnetic field – is the only known effect that allows one to directly measure the intensity of the magnetic field in the interstellar medium.

However, for magnetic fields maintained in the space between stars, the Zeeman effect is very small in magnitude. The frequency shift of spectral lines in observations of molecular clouds is only a few billionths of the original frequency of the splitting lines.

In 2003, scientists discovered, while observing molecular clouds, lines associated with atomic hydrogen and called HINSA. This set of lines is formed when atomic hydrogen is cooled by collisions with hydrogen molecules. The HINSA lines have an intensity 5-10 times higher than the lines of molecular hydrogen, so they can effectively detect the Zeeman effect in the case of molecular clouds and determine the intensity of the magnetic field with its help. According to measurements by Dee and his team, the average magnetic flux density of L1544 was about 4 microgauss, that is, this magnetic field is 6 million times weaker than the Earth’s magnetic field. Moreover,


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