标题： 麦哲伦星云带中的冷气体 显示英文标题

标题： Cool Gas in the Magellanic Stream

摘要： 我们首次直接探测到了麦哲伦云流中的冷原子气体，在澳大利亚 compact array 面向背景射电源 J0119-6809 的 21 厘米线吸收中确认了这一点。 两个吸收组分分别位于日心速度 218.6 公里/秒和 227.0 公里/秒处，光学深度约为 tau ~ 0.02。 对应的 H I 发射区域的列密度超过 2 x 10^20 cm^{-2}。 发射气体的推断自旋温度约为 70 K。在另外三个射电连续源的观测中，我们未能发现冷气体。 尽管我们在流中明确检测到冷气体，但其自旋温度高于类似成分在 LMC、SMC 和桥中的自旋温度，并且它对总 H I 密度的贡献可能较低。 没有发现与冷气体相关的 12CO(J = 1 -> 0) 或尘埃，表明该云团未在形成恒星。 显示英文摘要

摘要： We present the first direct detection of cold atomic gas in the Magellanic Stream, through 21 cm line absorption toward a background radio source, J0119 - 6809, using the Australia Telescope Compact Array. Two absorption components were identified at heliocentric velocities 218.6 km/s and 227.0 km/s, with optical depths of tau ~ 0.02. The corresponding H I emission region has a column density in excess of 2 x 10^20 cm^{-2}. The inferred spin temperature of the emitting gas is ~70 K. We failed to find cool gas in observations of three other radio continuum sources. Although we have definitively detected cool gas in the Stream, its spin temperature is higher than similar components in the LMC, SMC and Bridge, and its contribution to the total H I density is probably lower. No corresponding 12CO(J = 1 -> 0) or dust appears to be associated with the cool gas, suggesting that the cloud is not forming stars.