年青行星状星云NGC7027 HCO^+谱线发射的一个模型

A MODEL FOR HCO^+ LINE EMISSION IN THE YOUNG PLANETARY NEBULA NGC7027

对在年青行星状星云 NGC7027中新发现的 HCO^+分子离子谱线进行了研究.采用具有不同速度的双壳层膨胀模型,计算了 NGC7027 HCO^+,J=1-0,v=89.2GHz 的谱线发射.将模型结果与观测资料进行比较,导出了双壳层的膨胀速度和半径.发现谱线的理论轮廓与观测轮廓符合甚好.它说明,双壳层的运动学模型对年青行星状星云离子分子谱线的形成可能有重要的作用.

A model is constructed for newly discovered HCO^+ line emission in the zoungyoung planetary nebula NGC7027.The theoretical profile of HCO^+ emission line at 89.2 GHz calculated based on a model of double circumstellar shells with different expanding velociities.Comparing it with observational data,the expanding velocities and radius of double shells are obtained and the line profile agrees perfectly with the observa- tion of HCO^+ line emission.It shows that the double shell medel may play an important role in forming the line profile of the young planetary nebula.