Related Experiment Video
Updated: Apr 29, 2026

Study of Protein Dynamics via Neutron Spin Echo Spectroscopy
Published on: April 13, 2022
Possible evidence for free precession of a strongly magnetized neutron star in the magnetar 4U 0142+61
K Makishima1, T Enoto2, J S Hiraga3
1Department of Physics, Graduate School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan and Research Center for the Early Universe, Graduate School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan and MAXI team, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Abstract:
Magnetars are a special type of neutron stars, considered to have extreme dipole magnetic fields reaching ∼ 10(11) T. The magnetar 4 U 0142+61, one of the prototypes of this class, was studied in broadband x rays (0.5-70 keV) with the Suzaku observatory. In hard x rays (15-40 keV), its 8.69 sec pulsations suffered slow phase modulations by ± 0.7 sec, with a period of ∼ 15 h. When this effect is interpreted as free precession of the neutron star, the object is inferred to deviate from spherical symmetry by ∼ 1.6 × 10(-4) in its moments of inertia. This deformation, when ascribed to magnetic pressure, suggests a strong toroidal magnetic field, ∼ 10(12) T, residing inside the object. This provides one of the first observational approaches towards toroidal magnetic fields of magnetars.
Related Concept Videos
Atomic Nuclei: Larmor Precession Frequency
Atomic Nuclei: Magnetic Resonance
Gyroscope: Precession
Atomic Nuclei: Nuclear Relaxation Processes
Magnetic Field Lines
Magnetic field lines follow several hard-and-fast rules:
Magnetic Field due to Moving Charges
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...

