Extended Structures of Planetary Nebulae Detected in H2 Emission
Extended Structures of Planetary Nebulae Detected in H2 Emission
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DOI：
10.3847/1538-4357/aac01e
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发表时间：
2018-04
期刊：
影响因子：
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通讯作者：
X. Fang;Yong Zhang;S. Kwok;C. Hsia;Wayne Chau;G. Ramos-Larios;M. Guerrero
中科院分区：
文献类型：
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作者：
X. Fang;Yong Zhang;S. Kwok;C. Hsia;Wayne Chau;G. Ramos-Larios;M. Guerrero
我们在H2 2.122 μm和Brγ 2.166 μm发射谱线以及Kc 2.218 μm连续谱线中获得了11个银河系行星状星云（PNe）的窄带近红外图像。这些图像是由3.6米加拿大-法国-夏威夷望远镜（CFHT）上的宽视场红外相机收集的；它们前所未有的深度和广阔的视野使我们能够在几个星云星云的H2发射中发现扩展的星云结构，其中一些是第一次被探测到。用光学图像类比研究了H2发射的星云形态，并讨论了恒星风相互作用的指示。特别是，NGC 6772中高度不对称晕的完整结构在H2中被观测到，这强烈表明它与星际介质相互作用。我们的样品证实了氢发射与PNe的双极性之间的一般相关性。H2气体的结状或丝状精细结构在几个环状PNe的内部区域被分解，也证实了之前的观点，即H2的发射主要来自于赤道区域完全电离物质中的结或团块。此外，蝴蝶形状的Sh 1-89的H2图像，在去除野星后，清晰地显示出腰部倾斜的环状结构。这些高质量的CFHT图像证明了后续详细的形态运动学研究是必要的，以便推断样品中一些PNe的真实物理结构。
We present narrowband near-infrared images of a sample of 11 Galactic planetary nebulae (PNe) obtained in the H2 2.122 μm and Brγ 2.166 μm emission lines and the Kc 2.218 μm continuum. These images were collected with the Wide-field Infrared Camera on the 3.6 m Canada–France–Hawaii Telescope (CFHT); their unprecedented depth and wide field of view allow us to find extended nebular structures in H2 emission in several PNe, some of these being the first detection. The nebular morphologies in H2 emission are studied in analogy with the optical images, and indication of stellar wind interactions is discussed. In particular, the complete structure of the highly asymmetric halo in NGC 6772 is witnessed in H2, which strongly suggests interaction with the interstellar medium. Our sample confirms the general correlation between H2 emission and the bipolarity of PNe. The knotty or filamentary fine structures of the H2 gas are resolved in the inner regions of several ring-like PNe, also confirming the previous argument that H2 emission mostly comes from knots or clumps embedded within fully ionized material at the equatorial regions. Moreover, the H2 image of the butterfly-shaped Sh 1-89, after removal of field stars, clearly reveals a tilted ring structure at the waist. These high-quality CFHT images justify follow-up detailed morphokinematic studies that are desired in order to deduce the true physical structures of a few PNe in the sample.