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Are Neutral Sunspot Winds Important for Penumbral Dynamics and the First Ionization Potential Effect?

J. R. Kuhn·H. Lin·H. Morgan
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Abstract

The low ionization state in parts of a sunspot may play an important role in its evolution and dynamical state. The cool magnetic interior region of the sunspot develops a substantial neutral atomic and molecular hydrogen osmotic pressure which can drive a wind outward from the umbra. Ambipolar diffusion against the magnetically pinned ionized plasma component can also distort the umbral magnetic field into a filamentary penumbral structure. This may be important for explaining the development of the sunspot penumbra and the Evershed flow. This fractionation process may also be important for the ``First Ionization Potential'' (FIP) effect seen in the solar wind. In support of this mechanism we find evidence for such ionization fractionization in UV observations of molecular hydrogen in a sunspot umbra and penumbra.

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J. R. Kuhn, H. Lin, H. Morgan. 2005-09-29. Are Neutral Sunspot Winds Important for Penumbral Dynamics and the First Ionization Potential Effect?. https://arxiv.org/abs/astro-ph/0509862

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