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The magnetic field is ubiquitous in the universe. Though it plays an essential role in various astrophysical phenomena, its real origin and evolution are poorly known. This article reviews the understanding of the latest research concerning magnetic fields in the interstellarmedium, theMilkyWay Galaxy, external galaxies, active galactic nuclei, clusters of galaxies, and the cosmic web. Particularly, the review is concentrated in the achievements that have been provided by centimeter- and meter-wavelength radio observations. The article also introduces various methods for analyzing linear polarization data, including synchrotron radiation, Faraday rotation, depolarization, and Faraday tomography. [ABSTRACT FROM AUTHOR]

We present the results of multi-epoch very long baseline interferometry (VLBI) water (H2O) maser observations carried out with the VLBI Exploration of Radio Astrometry toward the Cepheus A HW3d object. We measured for the first time relative proper motions of the H2O maser features, whose spatio-kinematics traces a compact bipolar outflow. This outflow looks highly collimated and expanding through ~280 AU (400 mas) at a mean velocity of ~21 km s-1 (~6 mas yr-1) without taking into account the turbulent central maser cluster. The opening angle of the outflow is estimated to be ~30 °. The dynamical timescale of the outflow is estimated to be ~100 years. Our results provide strong support that HW3d harbors an internal massive young star, and the observed outflow could be tracing a very early phase of star formation. We also have analyzed Very Large Array archive data of 1.3 cm continuum emission obtained in 1995 and 2006 toward Cepheus A. The comparative result of the HW3d continuum emission suggests the possibility of the existence of distinct young stellar objects in HW3d and/or strong variability in one of their radio continuum emission components. [ABSTRACT FROM AUTHOR]