The Oxygen Crisis

奖项编号：AST-0607295PI：Thomas AyresInstUTION：科罗拉多大学博尔德分校：氧气危机这里将进行的研究集中在太阳物理学和其他领域的一个重大争议上--即太阳氧气丰度的价值。在过去的几年里，对太阳大气和随后形成的被禁止的O、I和OH吸收特征的先进的3D依赖于时间的辐射-流体动力学模拟表明，推荐的太阳氧气丰度减少了近两倍。这一修正使太阳值接近于现在的星际介质和附近的B星的预期。然而，由于氧作为一个重要的内部不透明度来源的作用，这些值与太阳系内部的模型以及它们与日震学的良好一致性严重冲突。此外，最近对热红外中一氧化碳振动带的研究对光球层中三维对流模型的有效性提出了质疑，并支持氧丰度与以前的高值更一致。在此，将开展进一步的光球对流模拟的独立观测试验，主要是在热红外中，其中重要的连续谱和线不透明度源具有与可见光中的不同、更简单但互补的特征。次要目标是继续探索光球层的外边界，即所谓的磁过渡区，在这里，深大气中的等离子体控制让位于高层中的磁优势。在这个谜团中，4.66微米的CO带表明了超冷(T~3500K)气体的惊人存在，这些气体突出到了应该是温暖的、分子敌对的色层中。理解这个谜团对于全面描述外层大气中的热平衡和能量传输是至关重要的。太阳红外光谱成像技术的新进展将使已经在原型中进行了十年的观测研究成为可能。此外，目前的热轮廓模拟将扩展到新的示踪剂，如OHand CaII，并将利用一个独特的机会来协调红外成像光谱与NASA太阳光紫外探测火箭飞行。这个项目将增进我们对太阳大气结构和能量传输的了解，这与空间天气有关。除此之外，太阳的组成是天文学许多其他领域的关键基线。此外，高海拔的大气层“为研究与分子冷却灾难有关的过程提供了一个实验室”。这里的工作将提供研究生培训，相关仪器的开发将服务于更广泛的国家太阳天文台用户群体。除了通过专业出版物和会议记录进行宣传外，还将在这项工作中开展与国家科学基金会任务有关的各种外联项目和社区服务活动。

AWARD NO: AST-0607295PI: Thomas AyresINSTITUTION: University of Colorado at BoulderTITLE: The Oxygen CrisisABSTRACTThe research to be undertaken here is focused on a significant controversy in solarphysics and beyond - namely the value of the solar oxygen abundance. In the past fewyears, advanced 3D time-dependent radiation-hydrodynamics simulations of the solaratmosphere and subsequent formation of forbidden O I and OH absorption features havepointed to a reduction in the recommended solar oxygen abundance of nearly a factor oftwo. This revision brings the solar value near that expected from the present-dayinterstellar medium and nearby B stars. However, because of the role of oxygen as asignificant interior opacity source, such values are in severe conflict with models of thesolar interior and their excellent agreement with helioseismology. Moreover, recentstudies of carbon monoxide rovibrational bands in the thermal infrared have raisedquestions concerning the validity of the 3-D convection models in the mid-photosphereand support an oxygen abundance more consistent with previous high values.Here further independent observational tests of the photospheric convection simulationswill be developed, primarily in the thermal infrared where the important continuum andline opacity sources have a different, simpler, but complementary character to those inthe visible. A secondary objective is to continue exploration of the outer boundary of thephotosphere, the so-called Magnetic Transition Zone, where plasma control in the deepatmosphere gives way to magnetic dominance in the higher layers. In this enigmaticregion, the 4.66 micron CO bands indicate the surprising presence of ultra-cool (T ~ 3500K) gas protruding into what should be the warm, molecule-hostile chromosphere.Understanding this puzzle is essential to the full description of heat balance and energytransport in the outer atmosphere. New advances in solar IR spectral imaging technologywill enable the observational studies that have been carried out in prototype for a decade.In addition, current thermal profile modeling will be extended to new tracers such as OHand Ca II, and a unique opportunity to coordinate IR imaging spectroscopy with a NASAsolar UV sounding rocket flight will be exploited.This project will advance our knowledge of the Sun's atmospheric structure and energytransport, which is relevant to space weather. Beyond this, the composition of the Sun is acrucial baseline for many other areas of astronomy. Furthermore, the high-altitudeCOmosphere" provides a laboratory for the study of processes associated withmolecular cooling catastrophes."The work here will provide graduate training and the associated instrument developmentwill serve the broader National Solar Observatory user community. In addition todissemination through professional publications and conference proceedings, a variety ofoutreach projects and community service activities relevant to the NSF mission will becarried out in connection with this work.