Effect of the H I Lyα Chromospheric Flux Anisotropy on the Total Intensity of the Resonantly Scattered Coronal Radiation
Effect of the H I Lyα Chromospheric Flux Anisotropy on the Total Intensity of the Resonantly Scattered Coronal Radiation
复制标题
H I Lyα色球通量各向异性对共振散射日冕辐射总强度的影响
DOI：
10.1086/427903
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
F. Auchère
中科院分区：
文献类型：
--
作者：
F. Auchère
在模拟H I的共振散射日冕Lyα线时，通常假定色球源的强度是均匀的。我们研究这个假设的有效性。在建立了H I 121.6 nm和He II 30.4 nm谱线强度之间的相关性之后，我们利用SOHO EUV成像望远镜的数据建立了Lyα色球层的卡林顿图。这些图用于计算整个日冕和日光层的Lyα辐照度。在太阳活动极小期，在1 Au处发现15%的纬向各向异性，并且该值越靠近太阳越大。定量分析了通量各向异性对Lyα共振散射日冕辐射总强度的影响。我们发现，在太阳极小，均匀盘假设导致系统高估的总强度的极地地区平均15%。这种效应的演变与太阳活动和其他共振散射日冕线的情况下进行了讨论。
In modeling of the resonantly scattered solar coronal Lyα line of H I, the intensity of the chromospheric source is often assumed to be uniform. We investigate the validity of this assumption. After establishing a correlation between the H I 121.6 nm and He II 30.4 nm line intensities, we build Carrington maps of the Lyα chromosphere from SOHO EUV Imaging Telescope data. These maps are used to compute the Lyα irradiance throughout the corona and heliosphere. A 15% latitudinal anisotropy is found at 1 AU at solar minimum, and this value becomes larger closer to the Sun. The effect of the flux anisotropy on the total intensity of the Lyα resonantly scattered coronal radiation is quantified. We find that at solar minimum, the uniform-disk assumption leads to systematic overestimates of the total intensity of the polar regions by 15% on average. The evolution of this effect with solar activity and the case of other resonantly scattered coronal lines are discussed.