HAO Colloquium - Ivan Milic, University of Colorado

NLTE inversions: challenges and future prospects

To probe physical conditions in the upper photosphere and the chromosphere, one often has to turn to the spectral lines that are formed outside of the common approximation of local thermodynamic equilibrium (LTE). Even forward modeling of these lines is challenging, and the spectropolarimetric inversions (that is, fitting a model atmosphere to the observed line profiles) are even more so. Not only are the spectral line profiles computationally demanding to calculate, but the lines themselves are sensitive to the wide range of heights and different physical parameters. 

In this talk we will discuss recent progress in the field of the inversion of spectral lines formed in non-LTE, briefly describe newly developed inversion code SNAPI, and show inversion of a solar plage observed in sodium D lines. Finally, we will discuss machine learning approaches that could enable more feasible inversions of large data sets. 

Date and time: 
Wednesday, February 20, 2019 - 2:00pm to 3:00pm