超新星遗迹SN 1572周边的分子气体分布

The Distribution of Molecular Gas around SN 1572

超新星遗迹(Supernova remnant,简写为SNR)在早期阶段的结构和演化是与周围星际介质环境密切相关的,这些星际介质也就成为研究SNR演化的探针.观测了SN1572方向周围的^(12)CO(J=1-0)谱线,拟调查SN 1572周围CO气体的分布,为研究SN 1572与周围分子气体的关系以及该超新星遗迹的演化提供观测依据.观测结果表明,在视向速度V_(LSR)=-69～-58km s^(-1)范围内的CO分子气体与SN 1572成协,此速度成分来自一个大尺度分子云.分子气体沿着SNR的射电壳边缘连续地但非均匀地分布,形成一个包围着SNR的半封闭的分子壳层.整个东半边有着增强的发射,尤其是东北边缘处的CO发射最强.峰值发射位置的谱线呈致宽(>5km s^(-1))的速度特征,结合光学、红外、X-射线等其它波段在对应位置上的已有观测,都表明了快速的激波和抛出物质正膨胀进入东北边缘的分子气体中,与稠密的气体发生相互作用.这种相互作用将对SN 1572今后的演化有着重要的影响.

The structure and evolution of a supernova remnant depends largely upon ambient interstellar medium,so the interstellar medium can be the valid probe of investigating the evolution of SNRs. We have observed the 12CO line emission around the SN 1572 with 13.7m millimeter-wave telescope at Qinghai Station of PMO, in order to reveal distribution features of velocity and density in small scale. It is shown that the CO molecular gas with the velocity of-69--61km s^-1 is correlated with SN 1572, and the gas surrounds the SN 1572 along the edge of radio shell with the morphology of open shell. Enhanced emission of 12CO line extends along the northeastern boundary. The spectrum of shocked gas has more than 5km s^-1 half-width of velocity. Comparing X-ray, infrared and optical observation data, it indicates that fast blast wave and ejecta are expanding into a dense gas toward the northeast direction and interacting with this part of molecular gas.