The density and magnetic field of the dense cores of the molecular cloud L 1630

The density and magnetic field strength of the dense cores in the Orion B molecular cloud are derived from the observed radius and FWHM line width based on the model of a uniformly magnetic sphere. We obtain the average magnetic field strength of 110μG and the average density of 8 × 10⁴/cm³ for the 39 cores, which agree closely with the observations. The method for deriving the density and magnetic field strength is applicable to the cores with R>0.2pc.