Core orientations and magnetic fields in isolated molecular clouds

Abstract

Molecular clouds are sites of star formation. Magnetic fields are believed to play an important role in their dynamics and shaping morphology. We aim to study any possible correlation that might exist between the magnetic fields orientation inside the clouds and the magnetic fields at envelope scales and their connection with respect to the observed morphology of the selected clouds. We examine the magnetic field orientation towards the clouds L1512, L1523, L1333, L1521E, L1544, L1517, L1780, and L183, using optical and Planck polarization observations. We also found the correlation between the ambient magnetic field and core orientations derived using Astrodendrogram on the Herschel 250 μm data. We find that the magnetic fields derived from optical and Planck agree with each other. The derived magnetic fields are aligned along the observed emission of each cloud as seen in Herschel 250 μm data. We also find that the relative orientation between the cores and the magnetic fields is random. This lack of correlation may arise due to the fact that the core orientation could also be influenced by the different magnetization within individual clouds at higher densities or the feedback effects which may vary from cloud to cloud. The estimated magnetic field strength and the mass-to-flux ratio suggest that all the clouds are in a magnetically critical state except L1333, L1521E, and L183, where the cloud envelope could be strongly supported by the magnetic field lines.