行星形成盘中磷的难熔组分
The refractory fraction of phosphorus in planet-forming discs
- Institute for Theoretical and Computation Physics, Graz University of Technology（格拉茨工业大学理论与计算物理研究所）
- Tartu Observatory, University of Tartu（塔尔图大学塔尔图天文台）
- Department of Physics and Astronomy, University College London（伦敦大学学院物理与天文学系）
- Space Research Institute, Austrian Academy of Sciences（奥地利科学院空间研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过分析赫比格Ae/Be星的光谱，测得其原行星盘内部磷的难熔组分>96%，表明大部分磷以难熔矿物形式锁定在尘埃中，解释了原行星盘含磷分子观测缺失的现象。
AI中文摘要：
背景：磷（P）是地球生命的必需元素，也是行星形成历史的潜在示踪剂，但迄今为止尚未在原行星盘中检测到含磷分子。赫比格Ae/Be星会不断从原行星盘吸积物质，由于其包层较浅（对流层）或完全为辐射层，这会改变恒星光球层的组成；改变后的表面组成反映了吸积物质的组成，因此也反映了原行星盘内部的组成。这种恒星光球层的吸积污染在年轻A、B型星（年龄<50 Myr）的吸积结束后仍会持续。目标：我们旨在量化赫比格Ae/Be星周围原行星盘内部，锁定在尘埃中的磷的比例（磷的难熔组分）与气态磷的比例。方法：我们使用光学和紫外光谱测量5颗赫比格Ae/Be星的恒星参数和丰度，以比较它们的磷和铁（Fe）丰度；我们还使用了一颗20 Myr年龄的主序B型星，其磷和铁丰度由光学光谱估算。假设铁完全锁定在原行星盘内部的难熔储库中，恒星磷和铁丰度之间的参数化关系可得出锁定在难熔储库中的磷的比例。结果：我们发现原行星盘内部磷的难熔组分在后验分布的95百分位范围内>96%。结论：与HD 100546系统的先前发现一致，我们得出原行星盘内部的大部分磷锁定在尘埃中，可能以陨磷铁镍矿（schreibersite）或磷灰石等难熔矿物的形式存在；结合磷的低宇宙丰度，我们的结果也与迄今为止原行星盘中含磷分子的红外和毫米波观测缺失的情况相符。
英文摘要：
Context. Phosphorus (P) is an essential element for life on Earth and a potential tracer of planet formation history. However, there has been no detection of P-bearing molecules in protoplanetary discs so far. Herbig Ae/Be stars constantly accrete matter from their pro- toplanetary disc, which alters the composition of the stellar photosphere due to their shallow convective, or fully radiative, envelope. The altered surface composition reflects the composition of the accreting matter, and thus that of the inner protoplanetary disc. This accretion contamination of stellar photosphere can persist after accretion has ended in young A and B-type stars (age < 50 Myr). Aims. We aim to quantify the fraction of P locked in dust (the refractory fraction of P) compared to gas in the inner protoplanetary disc around Herbig Ae/Be stars. Methods. We measure the stellar parameters and abundance of 5 Herbig Ae/Be stars using optical and UV spectra, to compare their P and Fe abundances. We also used a 20 Myrs old main sequence B-type star, which has P and Fe abundance estimated from optical spectrum. Fe is assumed to be completely locked in refractory reservoirs in the inner disc. A parameterised relationship between the stellar P and Fe abundance gives the fraction of P locked in refractory reservoirs. Results. We find the refractory fraction of P in the inner protoplanetary disc to be > 96 % within 95th percentile of the posterior distribution. Conclusions. Consistent with a previous finding in the HD 100546 system, we conclude most of the P in the inner protoplanetary disc is locked in dust, likely in refractory minerals like schreibersite or apatite. Our result, combined with the low cosmic abundance of P, is also consistent with the lack of infrared and mm-wavelength observations of P-bearing molecules in protoplanetary discs to date.
