Integral field spectroscopy of planetary nebulae: mapping the line diagnostics and hydrogen-poor zones with VLT FLAMES
Integral field spectroscopy of planetary nebulae: mapping the line diagnostics and hydrogen-poor zones with VLT FLAMES
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DOI：
10.1111/j.1365-2966.2008.13051.x
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发表时间：
2008-02
影响因子：
4.8
通讯作者：
Y. Tsamis;J. Walsh;D. P'equignot;M. Barlow;I. J. Danziger;X.-W. Liu Ucl;ECF-ESO;Meudon;Trieste;Beijing
中科院分区：
文献类型：
--
作者：
Y. Tsamis;J. Walsh;D. P'equignot;M. Barlow;I. J. Danziger;X.-W. Liu Ucl;ECF-ESO;Meudon;Trieste;Beijing
本文给出了用甚大望远镜光纤大阵列多元素光谱仪Argus积分场单元首次专门研究银河系行星星云(PNE)的结果。用11.5×7.2-arcsec2 Argus阵列绘制了三个典型的银河盘PNE：在亚弧秒分辨率下获得了NGC5882主壳以及NGC6153和NGC7009大区域的二维光谱图，每个目标有297个空间像素。在396.4-507.8 nm范围内，每个目标获得了相应数量的297个光谱。绘制了发射线和星云物理性质的空间分辨地图，如电子温度、密度和离子丰度。氦和双电离碳、氧相对于氢的丰度由光学复合线(ORL)得到，而O2+的丰度也来自经典的碰撞激发线(CEL)。通过绘制PNE面上O2+的ORL/CEL丰度比[丰度差异因子(ADF)]，研究了与氧有关的丰度差异问题的发生。ADF在目标之间以及在目标中的位置也不同，在NGC6153的情况下达到∼40的值，在NGC7009的情况下达到∼30的值。建立了ADF与中心星的几何距离、等离子体表面亮度(NGC6153)以及靶的[O III]电子温度、等离子体电离态等物理性质的关联式。在所有情况下，天空平面上的温度涨落参数T2a(O2+)都很小。有人认为，这些结果进一步证明了在普通的PNE中存在一种独特的星云成分，它由缺氢、超金属富含的等离子体组成。在大约2个空间像素的C II和O II ORL丰度诊断中，包含这种假定成分的区域看起来像是起伏的，因此任何相关的构造的物理尺寸都应该小于∼1000天文单位。关于推断带的起源，我们认为可能涉及周星盘、Abell 30型结或螺旋型彗星球体。文中还讨论了星云发射线研究的意义。©2008 RAS。
Results from the first dedicated study of Galactic planetary nebulae (PNe) by means of optical integral field spectroscopy with the Very Large Telescope Fibre Large Array Multi Element Spectrograph Argus integral field unit are presented. Three typical Galactic disc PNe have been mapped with the 11.5 × 7.2-arcsec2 Argus array: 2D spectral maps of the main shell of NGC 5882 and of large areas of NGC 6153 and NGC 7009 with 297 spatial pixels per target were obtained at subarcsec resolutions. A corresponding number of 297 spectra per target were obtained in the 396.4-507.8 nm range. Spatially resolved maps of emission lines and of nebular physical properties such as electron temperatures, densities and ionic abundances were produced. The abundances of helium and of doubly ionized carbon and oxygen, relative to hydrogen, were derived from optical recombination lines (ORLs), while those of O2+ were also derived from the classic collisionally excited lines (CELs). The occurrence of the abundance discrepancy problem, pertaining to oxygen, was investigated by mapping the ratio of ORL/CEL abundances for O 2+ [the abundance discrepancy factor (ADF)] across the face of the PNe. The ADF varies between targets and also with position within the targets, attaining values of ∼40 in the case of NGC 6153 and ∼30 in the case of NGC 7009. Correlations of the ADF with geometric distance from the central star and plasma surface brightness (for NGC 6153), as well as with [O iii] electron temperature, plasma ionization state and other physical properties of the targets are established. Very small values of the temperature fluctuation parameter in the plane of the sky, t2A(O2+), are found in all cases. It is argued that these results provide further evidence for the existence in run-of-the-mill PNe of a distinct nebular component consisting of hydrogen-deficient, super-metal-rich plasma. The zones containing this posited component appear as undulations in the C ii and O ii ORL abundance diagnostics of about 2 spatial pixels across, and so any associated structures should have physical sizes of less than ∼1000 astronomical units. Regarding the origin of the inferred zones, we propose that circumstellar discs, Abell 30-type knots, or Helix-type cometary globules may be involved. Implications for emission-line studies of nebulae are discussed. © 2008 RAS.