Jellyfish galaxies have long tails of gas that is stripped from the disk by ram pressure due to the motion of galaxies in the intracluster medium in galaxy clusters. Here, we present the magnetic field strength and orientation within the disk and the (90-kpc-long) Hα-emitting tail of the jellyfish galaxy JO206. The tail has a large-scale magnetic field (>4.1 μG), a steep radio spectral index (α ≈ −2.0), indicating an ageing of the electrons propagating away from the star-forming regions, and extremely high fractional polarization (>50 %), indicating low turbulent motions. The magnetic field vectors are aligned with (parallel to) the direction of the ionized-gas tail and stripping direction. High-resolution simulations of a large, cold gas cloud that is exposed to a hot, magnetized turbulent wind show that the fractional polarization and ordered magnetic field can be explained by accretion of draped magnetized plasma from the hot wind that condenses onto the external layers of the tail, where it is adiabatically compressed and sheared. The ordered magnetic field, preventing heat and momentum exchange, may be a key factor in allowing in situ star formation in the tail.

水母星系具有长尾巴的气体，由于星系团簇内集群内介质中星系的运动，通过冲压压力将其从磁盘上剥离掉。在这里，我们介绍了水母星系JO206的圆盘和发射（90 kpc长）Hα的尾巴内的磁场强度和方向。尾部具有大范围的磁场（> 4.1μG），陡峭的无线电频谱指数（α≈-2.0），表明远离恒星形成区传播的电子老化，以及极高的分数极化（> 50％），表明湍流低。磁场矢量与电离气体尾部的方向和剥离方向对齐（平行）。对暴露于热磁化湍流中的大型冷气云的高分辨率模拟表明，分数极化和有序磁场可以通过热风中垂下的磁化等离子体积聚来解释，该等离子凝结在热风的外层上尾巴，绝热地压缩和剪切。防止热量和动量交换的有序磁场可能是允许在尾巴中原位形成恒星的关键因素。