Temperature variations from Hubble Space Telescope imagery and spectroscopy of NGC 7009
Temperature variations from Hubble Space Telescope imagery and spectroscopy of NGC 7009
复制标题
哈勃太空望远镜图像和 NGC 7009 光谱的温度变化
DOI：
10.1046/j.1365-8711.2002.05567.x
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发表时间：
2002
影响因子：
4.8
通讯作者：
P. Martin
中科院分区：
文献类型：
--
作者：
R. Rubin;N. Bhatt;R. Dufour;B. Buckalew;M. Barlow;Xiaowei Liu;P. Storey;B. Balick;G. Ferland;J. Harrington;P. Martin
我们提出了新的哈勃太空望远镜（HST）/WFPC 2图像和STIS长缝光谱的行星状星云NGC 7009。主要目标是获得高空间分辨率的固有线比[O III] 4364/5008，从而评估整个星云的电子温度（Te）和分数均方Te变化（t 2 A）。WFPC 2的Te图相当均匀;几乎所有的值都在9000 - 11000 K之间，较高的Te值与内部He ++区非常一致。结果表明，整个过程中t 2的值非常小-0.01-。我们的STIS数据允许更直接的确定Te和t 2，虽然面积比WFPC 2小得多。我们提出的结果从装箱的数据沿着狭缝到瓷砖是0.5弧秒平方（匹配狭缝宽度）。使用45个瓦片（不包括中心星星和STIS基准棒）的平均[O III]温度为10 139 K; t2为0.0035。此处报告的Te测量值是沿沿着每条视线的平均值。因此，尽管发现非常低的t 2，我们不能完全排除温度波动沿着视线的碰撞激发发射线推断的重元素丰度之间的大丰度差异的原因相比，来自重组线。
We present new Hubble Space Telescope (HST)/WFPC2 imagery and STIS long-slit spectroscopy of the planetary nebula NGC 7009. The primary goal was to obtain high spatial resolution of the intrinsic line ratio [O III] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (t 2 A ) across the nebula. The WFPC2 Te map is rather uniform; almost all values are between 9000‐11 000 K, with the higher Te values closely coinciding with the inner He ++ zone. The results indicate very small values ‐ 0.01 ‐ for t 2 throughout. Our STIS data allow an even more direct determination of Te and t 2 , albeit for a much smaller area than with WFPC2. We present results from binning the data along the slit into tiles that are 0.5-arcsec square (matching the slit width). The average [O III] temperature using 45 tiles (excluding the central star and STIS fiducial bars) is 10 139 K; t 2 is 0.0035. The measurements of Te reported here are an average along each line of sight. Therefore, despite finding remarkably low t 2, we cannot completely rule out temperature fluctuations along the line of sight as the cause of the large abundance discrepancy between heavy element abundances inferred from collisionally excited emission lines compared to those derived from recombination lines.