测量银道面上行星状星云的运动学距离

Planetary nebulae(PNe) are products of low- and intermediate-mass stars when they enter the last evolution period which is also an important stage of stellar evolution. Studying PNe can help us understand the process of stellar evolution, interstellar medium, components and chemical evolution of galaxies better. One of challenges in studying PNe is how to measure their distances accurately which would influence other physical parameters. Currently, only dozens of PNe among known about 3000 PNe have reliable distances. For most of the rest, distances only can be estimated by statistical methods which have lots of problems. Especially, it is more difficult to measure the distances of PNe in the crowed Galactic plane. Only a few valuable research works had previously been done on this aspect. We plan to build both HI and CO emission spectra and HI absorption spectrum in the direction of PNe to systematically measure the kinematic distances of PNe in the Galactic plane. We will employ data from large scale Galactic plane 1420MHz continuum and 21cm HI spectral-line surveys, including international Galactic plane survey finished recently and GASKAP survey to begin in 2013. In addition, we will consider the effects of HI gas's non-circular motion on the Galactic rotation curve and try to understand the impacts of both distance ambiguity inside the solar circle and the velocity reversal in outer Galactic spiral arms on distance measurements.

行星状星云（PNe）是中小质量恒星演化到晚期的产物，是恒星演化的一个重要阶段。对PNe的研究将有助于我们更好的了解恒星演化过程、星际介质以及星系的组成和化学演化。精确地测定PNe的距离是研究PNe的难点之一，距离精确与否会直接影响PNe其他物理参数的确定。目前，已知的约3000个PNe中只有几十个有较可靠的距离参数。剩下的大部分通过统计方法给出距离但存在着很多问题。特别是位于拥挤的银道面上的PNe，其距离的测定更困难,前人在这方面好的工作也不多.本课题将利用新近完成的和将在明年开始的大规模银道面1420MHz连续谱和21cm HI谱线巡天数据通过以测PNe 所在方向HI 辐射和吸收谱线为主以CO辐射谱为辅的方法，系统测量银道面上PNe的运动学距离. 同时也将考虑HI气体的非均匀运动对银河系圆旋转曲线模型的影响,尝试解决内银河区存在远近距离模糊和外银河区旋臂速度反转等对测距的影响问题。

行星状星云（PNe）是中小质量恒星演化到晚期的产物，是恒星演化的一个重要阶段。对PNe的研究将有助于我们更好的了解恒星演化过程、星际介质以及星系的组成和化学演化。精确地测定PNe的距离是研究PNe的难点之一，距离精确与否会直接影响PNe其他物理参数的确定。目前，已知的约3000个PNe中只有几十个有较可靠的距离参数。剩下的大部分通过统计方法给出距离但存在着很多问题。特别是位于拥挤的银道面上的PNe，其距离的测定更困难。.本课题利用最新的大规模银道面1420MHz连续谱和21cm HI谱线巡天数据，通过测量PNe所在方向HI辐射和吸收谱线为主以CO辐射谱为辅的方法，系统测量银道面上PNe的运动学距离，总结了一个银纬在±5°之间且观测到的1.4GHz射电流量密度大于50mJy的包含100个行星状星云（PNe）的源表。完成了一批行星状星云的运动学距离测量工作，将一批行星状星云的距离测量精度比提高了两到三倍，为更加准确地研究这些行星状星云的更多物理性质奠定了基础。同时考虑HI气体的非均匀运动对银河系圆旋转曲线模型的影响,尝试解决内银河区存在远近距离模糊和外银河区旋臂速度反转等对测距的影响问题。