First Detection of Magnetism in Massive Stars Beyond Our Galaxy

Magnetic fields have been detected for the first time in three massive stars in the Large and Small Magellanic Clouds. This discovery is significant as it offers insights into the role of magnetism in star formation and evolution, particularly in galaxies with young stellar populations. Credit: SciTechDaily.com

New findings reveal magnetic fields in three massive stars in the Magellanic Clouds, shedding light on the influence of magnetism on stellar evolution and the formation of neutron stars and black holes. The use of advanced spectropolarimetry techniques was crucial to overcome past observational challenges.

Magnetic fields have been discovered in three massive, hot stars within our neighboring galaxies, the Large and Small Magellanic Clouds, for the first time. Although magnetic fields in massive stars are not new to our own galaxy, their detection in the Magellanic Clouds is particularly significant due to the abundance of young, massive stars in these galaxies. This discovery offers a rare chance to investigate actively forming stars and explore the maximum mass a star can achieve while maintaining stability.

Impact of Magnetism on Star Evolution

Notably, magnetism is considered to be a key component in massive star evolution, with a far-reaching impact on their ultimate fate. It’s the massive stars with initially more than eight solar masses that leave behind neutron stars and black holes by the end of their evolution. Spectacular merging events of such compact remnant systems have been observed by gravitational wave observatories. Furthermore, theoretical studies propose a magnetic mechanism for the explosion of massive stars, relevant for gamma-ray bursts, x-ray flashes and supernovae.

“Studies of magnetic fields in massive stars in galaxies with young stellar populations provide crucial information on the role of magnetic fields in star formation in the early Universe with star-forming gas not polluted by metals,” says Dr. Swetlana Hubrig, from the Leibniz Institute for Astrophysics Potsdam (AIP) and first author of the study.

Most massive star-forming region NGC346 in the Small Magellanic Cloud in the constellation Toucan in the southern starry sky located some 200,000 light years away from Earth. Credit: NASA, ESA, Andi James (STScI)

Challenges in Measuring Stellar Magnetism

Stellar magnetic fields are measured using spectropolarimetry. For this circularly polarised starlight is recorded and the smallest changes in spectral lines are investigated. However, in order to achieve the necessary