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Paper: High Spectral Resolution Study of the He 10830 Spectral Region
Volume: 346, Large-scale Structures and their Role in Solar Activity
Page: 389
Authors: Malanushenko, O.; Livingston, W.; Jones, H.; Malanushenko, V.
Abstract: The He 1083 nm line, formed in the upper chromosphere, is used for observations of coronal holes (CHs) near their origins at the solar surface. The weak He profiles in CHs show some peculiarities such as asymmetry, broadening, and different ratios between spectral components. These effects are small and the influence of disturbing noise and approximations in reductions may be crucial for their definition. In the present work we used low noise and high spectral resolution observations carried out at the Kitt Peak McMath-Pierce telescope to establish the key characteristics of He profile. The shape of He profile is affected by telluric water line and we suggest a method for its correction. Also there are solar lines that lie between the main and second He components and overlap with both. If the He line is weak and blue shifted, as in a CH and in cell centers, the blends distort the visual shape of the main component and obscure the second component. As an example we analyze two integral spectra of CH and quiet Sun and confirm the broadening and minor blue shift of the He line in a CH. This result must be considered to be preliminary and the work is in progress.
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