(亚)毫米波长的观测为我们的太阳和其他恒星提供了互补的视角,提供对色球层的热和磁成分的重要见解。尽管太阳的(亚)毫米观测取得了根本性的进展,一些重要的方面需要现有天文台无法提供的诊断能力。特别是,在扩展的频率范围内同时观测辐射连续体将有助于不同层的映射,从而最终有助于太阳大气的3D结构。以非常高的时间节奏在太阳上甚至整个太阳盘上绘制大区域,对于系统地检测和跟踪耀斑的时间演变至关重要,而天气观测,即,每日地图,多年的时间将为这种波长范围内的太阳活动周期提供前所未有的视野。由于我们的太阳是研究活跃主序恒星大气的基本参考,使用相同的仪器观察太阳和其他恒星将释放巨大的诊断潜力,以了解恒星活动及其对系外行星的影响。阿塔卡马大口径亚毫米望远镜(AtLAST)提议在智利的阿塔卡马沙漠建造一个50m口径的单盘望远镜,将能够提供这些观测能力。配备了大量的探测器元件,用于在宽频率范围内探测辐射连续体,AtLAST将讨论广泛的科学主题,包括太阳色球层的热结构和加热,耀斑和突出物,和太阳活动周期。在这份白皮书中,讨论了AtLAST的关键科学案例及其技术要求。
我们的太阳和其他恒星的观测波长约为1毫米,即在红外和无线电波之间的范围内,提出了一个有价值的互补观点。尽管技术取得了显著进步,某些关键方面需要当前天文台无法提供的诊断能力。拟议的阿塔卡马大口径亚毫米望远镜(AtLAST),具有50米的光圈,并计划在智利的阿塔卡马沙漠高海拔地区建造,承诺解决这些观察需求。配备了覆盖宽频率范围的新型探测器,AtLAST可以解锁大量的科学研究,有助于更好地了解我们的主星。快速连续在宽频率范围内同时观测将能够对太阳的不同层进行成像,从而阐明了太阳大气的三维热和磁结构,并为许多长期存在的核心问题提供了重要线索,例如太阳的最外层如何被加热到非常高的温度,像突出物这样的大型结构的性质,以及耀斑和日冕物质抛射,即巨大的喷发,是生产的。由于对我们今天所依赖的技术基础设施的潜在破坏性影响,后者对现代社会特别感兴趣。另一个独特的可能性是研究太阳在这个波长范围内的长期演化,这将产生对其活动周期的重要见解。此外,太阳作为其他恒星的基本参考,由于它的接近,它是唯一可以进行如此详细调查的恒星。因此,太阳的结果将直接影响理解其他恒星及其对系外行星的影响。本文概述了使用AtLAST进行太阳观测的关键科学目标和技术要求。
Observations at (sub-)millimeter wavelengths offer a complementary perspective on our Sun and other stars, offering significant insights into both the thermal and magnetic composition of their chromospheres. Despite the fundamental progress in (sub-)millimeter observations of the Sun, some important aspects require diagnostic capabilities that are not offered by existing observatories. In particular, simultaneously observations of the radiation continuum across an extended frequency range would facilitate the mapping of different layers and thus ultimately the 3D structure of the solar atmosphere. Mapping large regions on the Sun or even the whole solar disk at a very high temporal cadence would be crucial for systematically detecting and following the temporal evolution of flares, while synoptic observations, i.e., daily maps, over periods of years would provide an unprecedented view of the solar activity cycle in this wavelength regime. As our Sun is a fundamental reference for studying the atmospheres of active main sequence stars, observing the Sun and other stars with the same instrument would unlock the enormous diagnostic potential for understanding stellar activity and its impact on exoplanets. The Atacama Large Aperture Submillimeter Telescope (AtLAST), a single-dish telescope with 50m aperture proposed to be built in the Atacama desert in Chile, would be able to provide these observational capabilities. Equipped with a large number of detector elements for probing the radiation continuum across a wide frequency range, AtLAST would address a wide range of scientific topics including the thermal structure and heating of the solar chromosphere, flares and prominences, and the solar activity cycle. In this white paper, the key science cases and their technical requirements for AtLAST are discussed.
Observations of our Sun and other stars at wavelengths of around one millimeter, i.e. in the range between infrared and radio waves, present a valuable complementary perspective. Despite significant technological advancements, certain critical aspects necessitate diagnostic capabilities not offered by current observatories. The proposed Atacama Large Aperture Submillimeter Telescope (AtLAST), featuring a 50-meter aperture and slated for construction at a high altitude in Chile’s Atacama desert, promises to address these observational needs. Equipped with novel detectors that would cover a wide frequency range, AtLAST could unlock a plethora of scientific studies contributing to a better understanding of our host star. Simultaneous observations over a broad frequency range at rapid succession would enable the imaging of different layers of the Sun, thus elucidating the three-dimensional thermal and magnetic structure of the solar atmosphere and providing important clues for many long-standing central questions such as how the outermost layers of the Sun are heated to very high temperatures, the nature of large-scale structures like prominences, and how flares and coronal mass ejections, i.e. enormous eruptions, are produced. The latter is of particular interest to modern society due to the potentially devastating impact on the technological infrastructure we depend on today. Another unique possibility would be to study the Sun’s long-term evolution in this wavelength range, which would yield important insights into its activity cycle. Moreover, the Sun serves as a fundamental reference for other stars as, due to its proximity, it is the only star that can be investigated in such detail. The results for the Sun would therefore have direct implications for understanding other stars and their impact on exoplanets. This article outlines the key scientific objectives and technical requirements for solar observations with AtLAST.