Observables of Ion-Neutral Interaction Effects in the Solar Chromosphere

Friday, 19 December 2014
Juan Martínez-Sykora1, Bart De Pontieu2, Viggo H Hansteen2,3, Tiago M.D. Pereira3, Jorrit Leenaarts4 and Mats Carlsson5, (1)LMSAL, San Francisco, CA, United States, (2)Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA, United States, (3)Institute for Theoretical Astrophysics, Oslo, Norway, (4)Stockholm University, Stockholm, Sweden, (5)University of Oslo, Oslo, Norway
The chromosphere and transition region constitute the interface between the solar surface and the corona and modulate the flow of mass and energy into the upper atmosphere. IRIS was launched in 2013 to study the chromosphere and transition region. The complexity of the chromosphere is due to various regime changes that take place across it, like: Hydrogen goes from predominantly neutral to predominantly ionized; the plasma behavior changes from collisional to collision-less; it goes from gas-pressure dominated to magnetically driven, etc. Consequently, the interpretation of chromospheric observations in general and those from IRIS, in particular, is a challenging task. It is thus crucial to combine IRIS observations with advanced radiative-MHD numerical modeling. Because the photosphere, chromosphere and transition region are partially ionized, the interaction between ionized and neutral particles has important consequences on the magneto-thermodynamics of these regions. We implemented the effects of partial ionization using generalized Ohm’s law in the Bifrost code (Gudiksen et al. 2011) which solves the full MHD equations with non-grey and non-LTE radiative transfer and thermal conduction along magnetic field lines. The implementation of partial ionization effects impact our modeled radiative-MHD atmosphere, such as producing chromospheric heating and diffusion of photospheric magnetic field into the upper-chromosphere. We will focus on which observables of these processes can be revealed with IRIS.