In this study , the detailed magnetic field structure of the dense protostellar core Barnard 335 ( B335 ) was revealed based on near-infrared polarimetric observations of background stars to measure dichroically polarized light produced by magnetically aligned dust grains in the core .
Magnetic fields pervading B335 were mapped using 24 stars after subtracting unrelated ambient polarization components , for the first time revealing that they have an axisymmetrically distorted hourglass-shaped structure toward the protostellar core .
On the basis of simple two- and three-dimensional magnetic field modeling , magnetic inclination angles in the plane-of-sky and line-of-sight directions were determined to be 90 ^ { \circ } \pm 7 ^ { \circ } and 50 ^ { \circ } \pm 10 ^ { \circ } , respectively .
The total magnetic field strength of B335 was determined to be 30.2 \pm 17.7 \mu { G } .
The critical mass of B335 , evaluated using both magnetic and thermal/turbulent support against collapse , was determined to be M _ { cr } = 3.37 \pm 0.94 { M } _ { \odot } , which is identical to the observed core mass of M _ { core } = 3.67 M _ { \odot } .
We thus concluded that B335 started its contraction from a condition near equilibrium .
We found a linear relationship in the polarization versus extinction diagram , up to A _ { V } \sim 15 mag toward the stars with the greatest obscuration , which verified that our observations and analysis provide an accurate depiction of the core .