The Solar Oxygen Problem: Crisis, Catastrophe, or Opportunity?

科罗拉多大学的艾尔斯博士将对太阳外层进行多方面的研究。一场关于通常可能被视为最神秘的细节的争论动摇了太阳物理学：氧气丰度。在过去的几年里，光球层中测量到的丰度暴跌了近两倍，主要是因为复杂的3D对流模型应用于关键的原子示踪，如原子氧和含氧分子，如OH和CO。新的低值据说解决了热星和星际介质丰度方面的几个悬而未决的问题，但代价是破坏了之前太阳内部理论模型(氧气是关键的不透明度来源)与日震学高精度内部声速剖面之间的惊人一致。太阳低氧问题近乎于一场危机，人们考虑到从根本上依赖太阳提供基线化学成分的天体物理学各个领域的后果；如果对太阳丰度和日震学的研究不能协调一致，甚至是一场灾难。本工作将通过多管齐下的战略解决这些不足之处。一个关键目标将是利用基特峰天文台最近升级的傅里叶变换光谱仪，以尽可能高的光谱分辨率和信噪比开发一系列新的太阳地图集。第二个目标是仔细测试最新一代的3D对流模型，并对上层进行必要的经验修改，以便将它们应用于分子形成问题。第三个相关的目标是继续探索光球层的外边界，在那里，深层大气的高度有序的纤维场变得严重扭曲和纠缠，导致局部加热，将气体喷射推向日冕，并通常造成严重破坏。这项研究将促进我们对太阳的了解，特别是大气结构和从深层光球层到具有磁性的复杂低色球层的能量传输；与空间天气有关，这是天文学中少数几个具有直接社会影响的领域之一。除了太阳之外，更好地确定氧(和碳)丰度以及碳和氧的稀有同位素，对于依赖太阳基线的许多天文学领域至关重要。与国家太阳天文台合作，正在进行的仪器开发将为更广泛的NSO用户群体服务；以及为计划在下一个十年运行的先进技术太阳望远镜(ATST)寻找路径。ATST不仅将使太阳观测者受益，而且还将使专门的夜间项目受益，例如对明亮物体附近的微弱红外源进行日冕成像。最后，将开展与国家科学基金会有关的各种外联项目和社区服务活动。

Dr. Ayres of the University of Colorado will undertake a multifaceted study of the outer layers of the Sun. A controversy has shaken solar physics, over what ordinarily might be seen as the most arcane of details: the oxygen abundance. In the past few years, the measured abundance in the photosphere has plummeted nearly a factor of two, driven mainly by application of sophisticated 3D convection models to key atomic tracers such as atomic oxygen and oxygen-bearing molecules like OH and CO. The new low value is said to resolve several outstanding questions in the abundances in hot stars and the interstellar medium, but at the expense of wrecking the previous spectacularly good agreement between theoretical models of the solar interior (where oxygen is a crucial opacity source) and highly precise internal sound speed profiles from helioseismology. The solar low-O problem borders on a crisis, when one considers ramifications for diverse areas of astrophysics that rely fundamentally on the Sun to provide a baseline chemical composition; and even a catastrophe if the studies of solar abundances and helioseismology cannot be reconciled. The present work will address these deficiencies with a multi-pronged strategy. A key objective will be to develop a series of new solar atlases at the highest possible spectral resolution and signal-to-noise, exploiting the recently upgraded Fourier transform spectrometer at Kitt Peak Observatory. A second objective will be to carefully test the most recent generation of 3D convection models, and to make such empirical modifications to the upper layers as necessary to apply them to molecular formation problems. A third, related objective, is to continue exploring the outer boundary of the photosphere, where the highly ordered fibril fields of the deep atmosphere become severely twisted and tangled, causing local heating, propelling jets of gas into the corona, and generally wreaking havoc. This study will advance knowledge of our Sun, specifically atmospheric structure and energy transport from the deep photosphere out to the magnetically complex low chromosphere; relevant to space weather, one of few areas in astronomy that has direct societal impact. Beyond the Sun, better determinations of the oxygen (and carbon) abundance, and the rare isotopes of C and O, are crucial to many areas of astronomy that rely on the solar baseline. Ongoing instrumental developments, in partnership with the National Solar Observatory, will serve the broader NSO user community; as well as path finding for the Advanced Technology Solar Telescope (ATST), slated for operation in the next decade. ATST will benefit not only solar observers, but also specialized nighttime projects such as coronography of faint IR sources near bright objects. Finally, a variety of outreach projects and community service activities relevant to NSF will be carried out.