For the first time, magnetic fields have been discovered in three massive hot stars in neighboring galaxies – the large and small Magellanic clouds. Previously, magnetic massive stars had been found in our galaxy, but the detection of magnetic fields in the Magellanic clouds is significant as these galaxies are home to numerous young massive stars. This presents a unique opportunity for studying the formation of stars and the mass limit at which a star remains stable.
Magnetic fields play a crucial role in the evolution of massive stars, greatly influencing their ultimate fate. Stars with an initial mass of more than eight solar masses typically leave behind neutron stars and black holes at the end of their lifecycle.
The dramatic events of mergers involving such compact objects have been observed by gravitational wave observatories. Theoretical studies also suggest that magnetic mechanisms can trigger explosions of massive stars, leading to phenomena such as gamma-ray bursts, X-ray flashes, and supernovae.
“Research on magnetic fields in massive stars within galaxies with young star populations provides valuable insights into the role of magnetic fields in star formation during the early universe, when gas was not yet enriched for star formation,” explained Dr. Svetlana Hubrig from the Potsdam Astrophysical Institute of Leibniz (AIP), the lead author of the study.
Measurements of stars’ magnetic fields are conducted using spectropolarimetry, where the circular polarized light from the star is captured and analyzed for the smallest changes in spectral lines. Achieving the necessary precision in polarization measurements requires high-quality data.
“This method is highly photon-demanding. This poses a challenge, as even the most prominent massive stars with more than eight solar masses appear relatively faint when observed in neighboring galaxies,” Dr. Silva Yarvinen from AIP pointed out.
Given these constraints, conventional high-resolution spectropolarimeters and small telescopes are not suitable for such studies. Hence, a low-resolution spectropolarimeter called FORS2, which is installed on one of the four 8-meter telescopes at the