银河系中最 [$O_{III}$] λ5007 发光行星状星云的候选体。I. NGC 6572、NGC 6884 和 M 1-71 的积分光学特性
Candidates for the most [$O_{III}$] $\lambda5007$-luminous planetary nebula in the Milky Way. I. Integrated light properties of NGC 6572, NGC 6884, and M 1-71
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中文总结 AI 辅助
本研究以银河系 PNLF 截止处的三个行星状星云候选体为对象，利用 PMAS 观测分析其特性，验证 PNLF 作为标准烛光的普适性。
中文摘要 AI 辅助
行星状星云光度函数（PNLF）的亮端截止是河外标准烛光。然而，PNLF 截止处行星状星云（PNe）的物理性质仅在近邻星系中被研究过，那里的 PNe 大多呈现为点源。银河系 PNLF 则因银河系 PNe 距离的不确定性而约束不足。基于最近一项利用盖亚（Gaia）距离开展的银河系 PNLF 巡天，我们旨在表征银河系 PNLF 截止处的 PN 候选体。我们使用波茨坦多孔径分光光度计（PMAS）观测了三个位于银河系 PNLF 截止处的 PN 候选体，测定了它们的化学丰度，并构建光电离模型以推导中心恒星光度（L）和有效温度（Teff）。我们约束了中心恒星质量及与恒星演化模型预测一致的最可能距离，利用这些距离确定了绝对星等 M5007。我们样本中的 PNe 位于银河系 PNLF 的亮端 1 星等范围内（-4.20 < M5007 < -3.60），具有相似的星云特性和较窄的前身星质量范围（1.30-1.75 太阳质量）。测得的消光主要由银河系前景消光主导。我们样本 PNe 的星云周消光与中心恒星质量之间的趋势，与大麦哲伦云（LMC）和 M31 中推导的结果一致。所有样本 PNe 的光谱中均呈现弱发射线星（wels）特征，但我们确认其中部分谱线源自星云。这些 PNe 在星云特性和演化阶段上相似，其特征也与 LMC 和 M31 中最 [OIII]5007 发光的 PNe 相符。我们证明了星云周消光和初始-最终质量关系（IFMR）对于理解 PNLF 作为标准烛光的普适性的重要性。
英文摘要
The bright-end cutoff of the planetary nebula luminosity function (PNLF) serves as an extragalactic standard candle. However, the physical properties of planetary nebulae (PNe) at the PNLF cutoff have been studied only in nearby galaxies, where the PNe appear mostly as point sources. Galactic PNLF is further poorly constrained, primarily due to uncertainties in Galactic PN distances. Following a recent Galactic PNLF survey based on Gaia distances, we aim to characterise PN candidates at the Galactic PNLF cutoff. We observed three PN candidates at the Galactic PNLF cutoff using the Potsdam Multi-Aperture Spectrophotometer (PMAS). We determined their chemical abundances and constructed photoionisation models to derive the central star luminosity (L) and effective temperature (Teff). We constrained the central star masses and most likely distances consistent with the prediction of stellar evolution models. Using these distances, we determined the absolute magnitude M5007. PNe of our sample are located within the top 1 mag of the Galactic PNLF (-4.20 < M5007 <-3.60), with similar nebular properties and a narrow progenitor mass range (1.30-1.75 Msolar). The measured extinction is mostly dominated by the foreground Galactic extinction. The trend between the circum-nebular extinction and central star mass of our PNe is in agreement with those derived in the Large Magellanic Cloud (LMC) and M31. All PNe in our sample exhibit weak-emission line star (wels) features in their spectra, but we confirmed that some of these lines originate from the nebula. The PNe are similar in terms of their nebular properties and evolutionary stage. Their characteristics are also consistent with the most [OIII]5007-luminous PNe in the LMC and M31. We demonstrate the importance of circum-nebular extinction and the initial-final mass relation (IFMR) to understand the universality of PNLF as a standard candle.
