Energetic radiation from exoplanet hosts: The most detailed study of our nearest host star Proxima Centauri

Proxima Cen B是离地球最近的系外行星--而且可能适合居住。然而，后者主要依赖于来自其宿主星星的高能辐射的照明，这是一个活跃的M矮星。没有模型存在，允许足够准确的预测恒星的高能光谱，以回答问题的可居住性没有详细的观测在X射线和紫外regimes.We组织了迄今为止最广泛的X射线到紫外观测活动的Proxima Cen同时测量完整的高能光谱前所未有的细节。这包括使用低能透射光栅光谱仪覆盖约2 - 175 A波长的175 k的钱德拉X射线覆盖范围，伴随着哈勃空间望远镜紫外线数据的五个同步轨道，以及ASTROSAT卫星在更高能量的覆盖范围，加上支持地面数据。该项目的目标是双重的：首先，我们将为Proxima Cen的不同活动水平创建宽带光谱能量分布，以便详细评估我们最近的系外行星邻居的可居住性，其次，利用目标的接近程度来促进我们对低质量恒星上的磁活动的理解，这些恒星可能超过我们银河系中其他类型的行星宿主。因此，为了更好地了解孕育生命所必需的天体物理条件以及这些条件在我们的银河系中有多普遍，即，直接解决了宣布优先计划“探索太阳系外行星的多样性”（SPP 1992）时提出的主要问题之一。

Proxima Cen b is the nearest exoplanet to Earth - and possibly habitable. The latter, however, depends critically on the illumination by high-energy radiation from its host star, which is an active M dwarf. No models exist that allow a sufficiently accurate prediction of the stellar high-energy spectrum to answer the question of habitability without detailed observations in the X-ray and UV regimes.We have organized the so far most extensive X-ray to UV observing campaign of Proxima Cen to simultaneously measure the complete high-energy spectrum with unprecedented detail. This includes a massive 175 ks of Chandra X-ray coverage using the Low Energy Transmission Grating Spectrometer covering wavelengths from about 2 - 175 A, accompanied by five simultaneous orbits of Hubble Space Telescope UV data as well as coverage at higher energies with the ASTROSAT satellite, plus supporting ground-based data. The goals of this project are twofold: First, we will create broad-band spectral energy distributions for different activity levels of Proxima Cen to enable a detailed assessment of the habitability of our nearest exoplanetary neighbor and, second, to use the proximity of the target to advance our understanding of magnetic activity on low-mass stars, which likely outnumber other types of planet hosts in our Galaxy. Hence, to better understand the astrophysical conditions necessary to harbor life and how common these are in our Milky Way, i.e., directly addresses the one of the main questions posed in the announcement of the Priority Programme "Exploring the Diversity of Extrasolar Planets" (SPP 1992).