Modeling the magnetic field in the protostellar source NGC 1333 IRAS 4A

• Published in: Astronomy and astrophysics (Berlin) Vol. 490; no. 3; pp. L39 - L42
• Main Authors: Gonçalves, J., Galli, D., Girart, J. M.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 01.11.2008
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; ISM: magnetic fields; magnetohydrodynamics (MHD); polarization; stars: formation; Collapse; Polarization; Magnetohydrodynamics; Critical value; Molecular clouds; Mass transfer; Protostars; Stokes parameters; stars: formation; Alignment; Convolution; Star formation; Morphology; Mass ratio; Models; Modelling; Magnetic fields; magnetohydrodynamics (MHD); Age; Solar type star; ISM: magnetic fields
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:200810861

Context. Magnetic fields are believed to play a crucial role in the process of star formation. Aims. We compare high-angular resolution observations of the submillimeter polarized emission of NGC 1333 IRAS 4A, tracing the magnetic field around a low-mass protostar, with models of the collapse of magnetized molecular cloud cores. Methods. Assuming a uniform dust alignment efficiency, we computed the Stokes parameters and synthetic polarization maps from the model density and magnetic field distribution by integrations along the line-of-sight and convolution with the interferometric response. Results. The synthetic maps are in good agreement with the data. The best-fitting models were obtained for a protostellar mass of 0.8 $M_\odot$, of age 9 $\times$ 104 yr, formed in a cloud with an initial mass-to-flux ratio ~2 times the critical value. Conclusions. The magnetic field morphology in NGC 1333 IRAS 4A is consistent with the standard theoretical scenario for the formation of solar-type stars, where well-ordered, large-scale, rather than turbulent, magnetic fields control the evolution and collapse of the molecular cloud cores from which stars form.