A new study using the Atacama Large Millimeter/submillimeter Array (ALMA) has uncovered how magnetic fields, gravity, and turbulence interact within two dense clumps near the center of the Milky Way, offering fresh insight into how stars form in such dense regions.

By combining high-resolution polarization observations from ALMA with previous data from the James Clerk Maxwell Telescope (JCMT), researchers from the Shanghai Astronomical Observatory of the Chinese Academy of Sciences mapped the magnetic field strength and orientation across different scales within the 20 km/s cloud in the galaxy's Central Molecular Zone (CMZ).

The results were published in the Astrophysical Journal on February 19.

Located approximately 26,000 light-years from Earth, the CMZ is one of the most central regions of the Milky Way. The study focuses on two massive clumps within the 20 km/s molecular cloud in the CMZ, referred to as Clump 1 and Clump 4.

Using ALMA's high-resolution polarization observations, the researchers found that the magnetic field strengths in these regions range from 0.3 to 3.1 milligauss (mG). When combined with JCMT polarization observations, this study reveals that at larger cloud scales (~2 light-years), the magnetic field dominates the dynamics. At smaller scales, such as cores (0.03–0.3 light-years) and condensations (less than 0.03 light-years), gravity begins to take over. This transition highlights the complex balance of forces at play in star-forming regions.

Furthermore, the researchers quantitatively analyzed magnetic tension and gravitational forces between individual cores and compared magnetic field orientations with the direction of gravitational pull. Their findings suggest that, although magnetic fields resist gravitational collapse, they are not strong enough to prevent gas from completely collapsing into dense cores. These results suggest that star formation may occur in these regions due to the combined effects of gravity, turbulence, and magnetic fields.

Together, these findings significantly enhance our understanding of the physical processes involved in star formation, particularly in the extreme environment of the CMZ. By revealing the complex interactions among magnetic fields, gravity, and turbulence, this study paves the way for future exploration of molecular cloud dynamics and the mysteries of stellar birth.