arXiv 0801.21472008-01-14astro-ph

行星状星云的独立发射和吸收丰度

Independent Emission and Absorption Abundances for Planetary Nebulae

Robert Williams, Edward B. Jenkins, Jack A. Baldwin, Yong Zhang, Brian Sharpee, Eric Pellegrini, Mark Phillips

备注：: 19 pages, 13 figures, accepted by ApJ. Preprint utilizes emulateapj.cls v. 12/01/06 (included)
DOI：: 10.1086/529065

摘要：

由于行星状星云（PNe）和H II区域的禁止线和弱允许复合线的相对强度存在无法解释的差异，发射线丰度在十多年中一直不确定。在某些星云中，观测到的来自同一母离子的禁断线和复合线的强度与理论值相差一个数量级以上。在这项研究中，我们观察到的星云气体产生的PNe中心恒星的紫外共振线吸收，并从相同的离子发射光学禁戒线。然后，我们比较了来自地面观测的星云禁戒线的发射措施的吸收柱密度。我们发现，我们的样品PNe的碰撞激发的禁线产生列密度是在基本一致的列密度来自相同的离子从紫外线吸收线。一个类似的比较，涉及复合线列密度产生较差的协议，虽然附近的限制的正式不确定性的分析。在更有力地说明复合线丰度不正确之前，需要对丰度差异因子较大的天体的另一个样本进行研究。

英文摘要：

Emission-line abundances have been uncertain for more than a decade due to unexplained discrepancies in the relative intensities of the forbidden lines and weak permitted recombination lines in planetary nebulae (PNe) and H II regions. The observed intensities of forbidden and recombination lines originating from the same parent ion differ from their theoretical values by factors of more than an order of magnitude in some of these nebulae. In this study we observe UV resonance line absorption in the central stars of PNe produced by the nebular gas, and from the same ions that emit optical forbidden lines. We then compare the derived absorption column densities with the emission measures determined from ground-based observations of the nebular forbidden lines. We find for our sample of PNe that the collisionally excited forbidden lines yield column densities that are in basic agreement with the column densities derived for the same ions from the UV absorption lines. A similar comparison involving recombination line column densities produces poorer agreement, although near the limits of the formal uncertainties of the analyses. An additional sample of objects with larger abundance discrepancy factors will need to be studied before a stronger statement can be made that recombination line abundances are not correct.

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