Search

Most molecular clouds are filamentary or elongated.sup.1,2,3. For those forming low-mass stars (8 solar masses). But whether the core field morphologies are inherited from the intercloud medium or governed by cloud turbulence is unknown, as is the effect of magnetic fields on cloud fragmentation at scales of 10 to 0.1 parsecs.sup.7,8,9. Here we report magnetic-field maps inferred from polarimetric observations of NGC 6334, a region forming massive stars, on the 100 to 0.01 parsec scale. NGC 6334 hosts young star-forming sites.sup.10,11,12 where fields are not severely affected by stellar feedback, and their directions do not change much over the entire scale range. This means that the fields are dynamically important. The ordered fields lead to a self-similar gas fragmentation: at all scales, there exist elongated gas structures nearly perpendicular to the fields. Many gas elongations have density peaks near the ends, which symmetrically pinch the fields. The field strength is proportional to the 0.4th power of the density, which is an indication of anisotropic gas contractions along the field. We conclude that magnetic fields have a crucial role in the fragmentation of NGC 6334. Polarimetric observations of magnetic-field orientations in a filamentary molecular cloud forming massive stars shows that the magnetic field strongly affects fragmentation in the region. Massive-star formation observed In contrast to most known regions of massive-star formation, the 'Cat's Paw Nebula' NGC 6334 is relatively nearby, just 1.7 kiloparsecs from Earth. At this distance it is possible to use starlight polarization to probe magnetic field alignments in star-forming filamentary clouds. Hua-bai Li et al. report B-field maps inferred from polarimetric observations of NGC 6334 on the 100 to 0.01 parsec scale. They conclude that magnetic fields have a crucial role in the fragmentation of NGC 6334, throwing new light on the long-standing question of how magnetic field topology evolves as molecular clouds form out of the interstellar medium and as cores contract to form stars., Author(s): Hua-bai Li [sup.1] , Ka Ho Yuen [sup.1] , Frank Otto [sup.1] , Po Kin Leung [sup.1] , T. K. Sridharan [sup.2] , Qizhou Zhang [sup.2] , Hauyu Liu [...]

Most molecular clouds are filamentary or elongated (1-3). For those forming low-mass stars (8 solar masses). But whether the core field morphologies are inherited from the intercloud medium or governed by cloud turbulence is unknown, as is the effect of magnetic fields on cloud fragmentation at scales of 10 to 0.1 parsecs (7-9). Here we report magnetic-field maps inferred from polarimetric observations of NGC 6334, a region forming massive stars, on the 100 to 0.01 parsec scale. NGC 6334 hosts young star-forming sites (10-12) where fields are not severely affected by stellar feedback, and their directions do not change much over the entire scale range. This means that the fields are dynamically important. The ordered fields lead to a self-similar gas fragmentation: at all scales, there exist elongated gas structures nearly perpendicular to the fields. Many gas elongations have density peaks near the ends, which symmetrically pinch the fields. The field strength is proportional to the 0.4th power of the density, which is an indication of anisotropic gas contractions along the field. We conclude that magnetic fields have a crucial role in the fragmentation of NGC 6334., At a distance of about 1.7 kiloparsecs from Earth, NGC 6334 is one of the nearest regions forming massive stars. Other sites forming massive stars are usually too far away [...]