Understanding the chromosphere-corona interface in the Solar Orbiter and DKIST era

经过近20年的努力、规划和建设，这两个下一代长期主要太阳能设施将于2020年初投入运营。这是DKIST和ESA的太阳轨道器。DKIST是第一个大型太阳望远镜，有一个4米的离轴镜。它已在夏威夷的毛伊岛建造，将于2019年首次亮相，并于2020年开始运营，以前所未有的空间分辨率进行盘上和盘外观测。DKIST拥有各种各样的盘上仪器来观测光球/色球层，但也将投入大约一半的时间来观测1.5个太阳半径范围内的禁冕线。我们的目标是通过结合密度测量，色球层和日冕之间的能量和质量转移仍然知之甚少。这是非常复杂的建模，因为它需要非本地传输和时间依赖的非平衡原子过程，再加上MHD建模。该计划的一个关键方面是通过在原子速率的计算中增加密度依赖和光电离来改进色球层/过渡区原子过程的建模。太阳轨道器是欧空局的一项主要使命，将于2020年2月发射，致力于研究日光层的内部部分，我们的太阳系所在的气泡不断受到太阳事件的影响。其中一些事件与空间天气有关，即对地球大气层的外层产生重大影响，对卫星、人类太空飞行和通信等造成重大影响。太阳轨道器的主要科学目标之一是了解太阳风如何以及在何处从太阳表面释放和加速进入日光层。为了实现这一目标，该使命将与太阳进行近距离接触（0.3 Au以内），并拥有一套原位和遥感仪器。其中一个主要的遥感仪器是SPICE，这是一台在英国RAL建造的紫外光谱仪，能够测量多普勒流、温度和化学丰度，我们将利用它来定位现场观测到的太阳风源区，并研究太阳风的形成。SPICE将主要观测色球-日冕界面上形成的谱线，因此，它将适合于研究太阳过渡区，即太阳色球层和日冕之间的大气薄层。这一区域非常活跃，需要改进原子过程的模型，并纳入非平衡效应，以便对观测结果进行解释，我们还打算继续提供最基本的原子数据，以便对当前和未来的太阳飞行任务的观测结果进行解释。我们的团队，特别是Giulio Del Zanna，一直在通过不断更新CHIANTI原子数据库来领导这一领域，该数据库现在也被广泛用于研究天体物理和实验室等离子体。海伦梅森，一个著名的沟通将在这方面发挥关键作用。

After almost 20 years of hard work, planning and building, the two next-generation long-term major solar facilities will become operational in early 2020. These are DKIST and ESA's Solar Orbiter. They are expected to provide breakthrough observations of the solar chromosphere/corona.DKIST is the first large-scale solar telescope, with a 4 m off-axis mirror. It has been built in Maui, Hawaii, will have first light in 2019 and start operations in 2020 by performing on-disk and off-disk observations with unprecedented spatial resolution. DKIST has a wide range of on-disk instruments to observe the photosphere / chromosphere, but will also devote about half of the time to coronagraph spectral observations of forbidden coronal lines, out to 1.5 solar radii.We aim to study the heating of the solar corona by combining measurements of densities, temperatures and magnetic fields with DKIST.The transfer of energy and mass between the chromosphere and corona is still poorly understood. The modelling of this is extremely complex as it requires non-local transport and time-dependent non-equilibrium atomic processes coupled with MHD modelling. A key aspect of the proposal is to improve the modelling of atomic processes in the chromosphere/transition-region by adding density-dependent and photo-ionisation into the calculation of atomic rates.Solar Orbiter is a major ESA mission to be launched in February 2020 and is dedicated to the study of the inner parts of the heliosphere, the bubble where our solar system resides that is constantly modified by events on the Sun. Some of these events have relevance to Space Weather, i.e. affect significantly the outer layers of the Earth atmosphere, causing significant effects on satellites, human space flight and communication, for example.One of the main science goals of Solar Orbiter is to understand how and where the solar wind is released and accelerated from the solar surface into the heliosphere. To achieve this goal, the mission will have close encounters (to within 0.3 AU) with the Sun, and has a suite of in-situ and remote-sensing instruments. One of the main remote sensing instruments is SPICE, a UV spectrometer built at RAL (UK) that is able to measure Doppler flows, temperatures and chemical abundances, which we shall use to locate the source region of the solar wind observed in-situ and to study the formation of the solar wind.SPICE will mainly observe lines formed in the chromosphere-corona interface, so it will be suited to studies of the solar transition region, the thin layer of theatmosphere between the chromosphere and corona of the Sun. This region is very dynamic, and improved modelling of atomic processes, together with the inclusion of non-equilibrium effects will be required for the interpretation of the observations.We also aim to continue to provide the most fundamental atomic data for the interpretation of the observations of current and future solar missions. Our group, in particular Giulio Del Zanna, has been leading this field by continuously updating the CHIANTI atomic database, now also widely used to study astrophysical and laboratory plasma.Finally, we shall communicate our work to the public and to schools. Helen Mason, a well known communicator will play a key role in this regard.