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arXiv 2407.06385astro-ph.SRastro-ph.GA
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高丰度偏差行星状星云NGC 6153的MUSE光谱研究

MUSE spectroscopy of the high abundance discrepancy planetary nebula NGC 6153

V. Gómez-Llanos, J. García-Rojas, C. Morisset, H. Monteiro, D. Jones, R. Wesson, H. M. J. Boffin, R. L. M. Corradi

AI总结:

本研究利用MUSE光谱仪观测高丰度偏差行星状星云NGC 6153,开发定制化分析方法证实其存在低温等离子体相,明确多等离子体相对精确测定高ADF行星状星云化学丰度的必要性。

摘要:

行星状星云(PNe)的丰度偏差问题长期困扰着天文学家。丰度偏差因子(ADF~10)较高的NGC 6153,为研究人员通过构建精细发射线图、考察电子温度与密度的变化来理解化学结构与电离过程提供了契机。我们使用MUSE光谱仪获取了积分场单元(IFU)数据,其波长覆盖范围为4600-9300 Å,空间采样为0.2角秒,光谱分辨率R在1600-3500之间。我们制作了60条发射线以及两个连续谱区域的发射线图,并开发了一套定制化的数据分析方法,包括对极光线的复合贡献校正以及不同等离子体相的贡献校正。分析证实了NGC 6153中存在低温等离子体成分:我们发现由复合线(RLs)和连续谱诊断得到的电子温度,显著低于碰撞激发线(CELs)诊断得到的电子温度。我们构建了离子化学丰度图,计算中考虑了冷等离子体相在HI发射中的权重。采用该方法后我们发现,与均匀HI发射情形下的结果相比,由CELs得到的离子丰度最高可低0.2 dex,由RLs得到的离子丰度最高可高1.1 dex。我们定义了两种等离子体成分之间的丰度对比度因子(ACF),其平均值比ADF高0.9 dex。不同电离校正因子(ICFs)的计算方法得到了一致的结果。本研究结果强调,在高ADF行星状星云中进行精确的化学丰度测定,必须考虑多等离子体相的影响。

英文摘要:

(Abridged) The abundance discrepancy problem in planetary nebulae (PNe) has long puzzled astronomers. NGC6153, with its high Abundance Discrepancy Factor (ADF~10), provides an opportunity to understand the chemical structure and ionisation processes by constructing detailed emission line maps and examining variations in electron temperature and density. We used the MUSE spectrograph to acquire IFU data covering the wavelength range 4600-9300 Å with a spatial sampling of 0.2 arcsec and spectral resolutions ranging from R = 1600-3500. We created emission line maps for 60 lines and two continuum regions. We developed a tailored methodology for the analysis of the data, including correction for recombination contributions to auroral lines and the contributions of different plasma phases. Our analysis confirmed the presence of a low-temperature plasma component in NGC6153. We find that electron temperatures derived from recombination line and continuum diagnostics are significantly lower than those derived from collisionally excited line diagnostics. Ionic chemical abundance maps were constructed, considering the weight of the cold plasma phase in the HI emission. Adopting this approach, we found ionic abundances that could be up to 0.2 dex lower for those derived from CELs and up to 1.1 dex higher for those derived from RLs than in the case of an homogeneous HI emission. The abundance contrast factor (ACF) between both plasma components was defined, with values, on average, 0.9 dex higher than the ADF. Different methods for calculating ionisation correction factors (ICFs) yielded consistent results. Our findings emphasise that accurate chemical abundance determinations in high-ADF PNe must account for multiple plasma phases.

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