We review the observations of supernova remnants (SNRs) and pulsar-wind nebulae (PWNe) that give information on the strength and orientation of magnetic fields. Radio polarimetry gives the degree of order of magnetic fields, and the orientation of the ordered component. Many young shell supernova remnants show evidence for synchrotron X-ray emission. The spatial analysis of this emission suggests that magnetic fields are amplified by one to two orders of magnitude in strong shocks. Detection of several remnants in TeV gamma rays implies a lower limit on the magnetic-field strength (or a measurement, if the emission process is inverse-Compton upscattering of cosmic microwave background photons). Upper limits to GeV emission similarly provide lower limits on magnetic-field strengths. In the historical shell remnants, lower limits on B range from 25 to 1000 microGauss. Two remnants show variability of synchrotron X-ray emission with a timescale of years. If this timescale is the electron-acceleration or radiative loss timescale, magnetic fields of order 1 mG are also implied. In pulsar-wind nebulae, equipartition arguments and dynamical modeling can be used to infer magnetic-field strengths anywhere from about 5 microGauss to 1 mG. Polarized fractions are considerably higher than in SNRs, ranging to 50 or 60% in some cases; magnetic-field geometries often suggest a toroidal structure around the pulsar, but this is not universal. Viewing-angle effects undoubtedly play a role. MHD models of radio emission in shell SNRs show that different orientations of upstream magnetic field, and different assumptions about electron acceleration, predict different radio morphology. In the remnant of SN 1006, such comparisons imply a magnetic-field orientation connecting the bright limbs, with a non-negligible gradient of its strength across the remnant.
Kinematically cold and warm planetary nebulae samples, HII regions and supernovae remnants in the disc of the face-on spiral galaxy NGC 628 (M74) -- The Planetary Nebulae Spectrograph with the H$α$ arm
ESO（欧洲南方天文台）；Max-Planck-Institüt fur Extraterrestrisches Physik（马克斯·普朗克地外物理研究所）；Research School of Astronomy and Astrophysics, Australia National University（澳大利亚国立大学天文学与天体物理学研究学院）；Oxford Astrophysics, University of Oxford（牛津大学牛津天体物理学）；Finnish Centre for Astronomy with ESO, (FINCA), University of Turku（图尔库大学芬兰ESO天文学中心）；Tuorla Observatory, Department of Physics and Astronomy, University of Turku（图尔库大学物理与天文学系图奥拉天文台）；Turku Collegium for Science, Medicine and Technology (TCSMT), University of Turku（图尔库大学科学、医学与技术学院）；School of Physics and Astronomy, University of Nottingham（诺丁汉大学物理与天文学院）；Universidade Federal do Rio de Janeiro, Observatório do Valongo（里约热内卢联邦大学瓦隆戈天文台）；Osservatorio Astronomico di Capodimonte, INAF（意大利国家天体物理研究所卡波迪蒙特天文台）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；Department of Physics “E. Pancini”, University of Naples Federico II（那不勒斯斐迪南多二世大学“E.潘奇尼”物理学系）；Department of Physics and Astronomy, San Jose State University（圣何塞州立大学物理与天文学系）
