垂死恒星的最后喘息：前行星状星云IRAS 06530-0213的ALMA观测
The Last Gasps of a Dying Star: ALMA Observations of the Pre-Planetary Nebula IRAS 06530-0213
- Chalmers University of Technology（查尔姆斯理工大学）
- Instituto de Física Fundamental (IFF-CSIC)（基础物理研究所（CSIC））
- Korea Astronomy and Space Science Institute（韩国天文学与空间科学研究院）
- Observatorio Astronómico Nacional (IGN/CNIG)（国家天文台（IGN/CNIG））
- University of Washington（华盛顿大学）
- University of Rochester（罗切斯特大学）
- Institut de Radioastronomie Millimétrique（毫米波射电天文研究所）
- Macquarie University（麦考瑞大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
通过ALMA高分辨率观测前行星状星云IRAS 06530，发现热脉冲后环状结构与中心双极星云，推断前身星质量及稀有同位素富集，揭示其演化历史。
AI中文摘要：
我们展示了高角分辨率（约0.1''-0.5''）的ALMA对前行星状星云IRAS 06530--0213（IRAS 06530）在毫米波谱线及连续谱（约0.44和0.88毫米）的观测。这些数据揭示了存在一个扩展的环状结构——这是碳星在后AGB阶段之前最后一次热脉冲的首个证据——以及一个中心双极星云（CBN）和环状体。IRAS 06530的AGB前身星的质量损失率在热脉冲后立即下降，随后在后AGB阶段之前再次上升，这由CBN周围的丝状弧结构所证实。这些弧结构可能是三维阿基米德螺旋结构的一部分，通常归因于双星伴星的存在。但我们未在IRAS 06530中心恒星位置发现致密连续谱源，例如与已知具有双星伴星的盘主导型后AGB天体中常见的致密尘埃盘相关的源。由环状体和CBN得出的膨胀年龄表明，IRAS 06530的前身星在约700年前过渡为后AGB恒星。IRAS 06530中喷出物的分子质量主要由丝状弧区域主导，其质量M_H2=(0.12-0.25) M_sun。与太阳值相比，IRAS 06530的环状体似乎显著（适度）富集了^13C和^17O（^15N）——这种稀有同位素富集模式与标准核合成模型不符。根据IRAS 06530的光度及其分离壳层的年龄，同时考虑其仍处于AGB阶段时的情况，我们推断IRAS 06530前身星的质量为(1.6-3.4) M_sun。
英文摘要：
We present high angular-resolution ($\sim 0.{''}1 - 0.{''}5$) ALMA observations of millimeter-wave line and continuum emission (at $\sim0.44$ and $0.88$ mm) in the pre-planetary nebula IRAS 06530--0213 (IRAS 06530). These data show the presence of an extended circular ring -- first evidence of the last thermal-pulse preceding the post-AGB phase in a carbon star -- and a central bipolar nebula (CBN) and torus. The mass-loss rate of IRAS 06530's AGB progenitor decreased immediately after the thermal pulse, then rose again just before the post-AGB phase as evidenced by the presence of filamentary arc structures around the CBN. The arc stuctures are likely part of a 3-D Archimidean spiral structure generally attributed to the presence of a binary companion. But we do not find a compact continuum source at the location of IRAS 06530's central star, such as that associated with the compact dusty disks typically found in disk-prominent post-AGB objects known to have binary companions. The expansion ages derived for the torus and CBN imply that IRAS 06530's progenitor transitioned to a post-AGB star $\lesssim700$ yr ago. The molecular mass of the ejecta in IRAS 06530 is dominated by the filamentary arc region with a mass $M_{H_2}=(0.12-0.25) M_{\odot}$. Compared with solar values, the torus of IRAS 06530 appears to be significantly (modestly) enriched in $^{13}$C and $^{17}$O ($^{15}$N) as well -- a pattern of rare-isotope enrichment inconsistent with standard nucleosynthesis models. From the luminosity of IRAS 06530 and the age of its detached shell, while it was still on the AGB, we infer that the mass of IRAS 06530's progenitor was $(1.6-3.4) M_{\odot}$.
