We present new radio images of the supernova remnant (SNR) CTA 1 at 1420 and 408 MHz, and in the 21 cm line of H i observed with the Dominion Radio Astrophysical Observatory Synthesis Telescope and at 1420 MHz observed with the Effelsberg 100 m telescope. We confirm previously described continuum features and elaborate further on filamentary features identified using the high-resolution (1′) maps from these new observations. We investigate the abrupt change in sign of rotation measure (RM) across the SNR, using the linear polarization observations in the four bands around 1420 MHz. Following X. H. Sun et al.’s (2011) investigation, we both confirm that the distribution of signs of the RMs for extragalactic sources in the area appears to match that of the shell, as well as combine the data from the four bands to estimate the relative depolarization and the intrinsic rotation measure of the SNR. We do not conclusively reject X. H. Sun et al.’s (2011) claim of a Faraday screen in the foreground causing the distribution of RMs that we observe; however, we do suggest an alternative explanation of a swept-up stellar wind from the progenitor star with a toroidal magnetic field. Finally, we expand on the analysis of the H i observations by applying the Rolling Hough Transform to isolate filamentary structure and better identify H i emission with the SNR. Further constraining the H i velocity channels associated with CTA 1, we use more recent Galactic rotation curves to calculate an updated kinematic distance of 1.09 ± 0.2 kpc.

中文翻译：

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超新星残骸 CTA 1 的新射电观测


我们展示了超新星残余物 （SNR） CTA 1 在 1420 和 408 MHz 的新射电图像，以及用 Dominion 射电天体物理天文台合成望远镜观测的 21 cm H i 线和用 Effelsberg 100 m 望远镜在 1420 MHz 观测的 H i 线。我们确认了先前描述的连续体特征，并进一步详细说明了使用这些新观测的高分辨率 （1'） 图识别的细丝特征。我们使用 1420 MHz 附近四个频段的线性极化观测来研究整个 SNR 中旋转符号测量 （RM） 的突然变化。在 X. H. Sun 等人（2011 年）的调查之后，我们都证实了该地区银河系外源的 RM 符号分布似乎与壳层的分布相匹配。 以及结合来自四个波段的数据来估计 SNR 的相对去极化和内禀旋转测量。我们并没有最终否定 X. H. Sun 等人 （2011） 的说法，即前景中的法拉第屏蔽导致了我们观察到的 RM 分布;然而，我们确实提出了另一种解释，即来自祖星的恒星风具有环形磁场。最后，我们通过应用 Rolling Hough 变换来分离细丝结构并更好地识别 SNR 的 H i 发射，从而扩展了对 H i 观测的分析。进一步限制与 CTA 1 相关的 H i 速度通道，我们使用最近的银河旋转曲线来计算 1.09 ± 0.2 kpc 的更新运动距离。