Tomography of a Solar Plage with the Tenerife Inversion Code

Abstract

We apply the Tenerife Inversion Code (TIC) to the plage spectropolarimetric observations obtained by the Chromospheric LAyer SpectroPolarimeter (CLASP2). These unprecedented data consist of full Stokes profiles in the spectral region around the Mg ii h and k lines for a single slit position, with around two thirds of the 196″ slit crossing a plage region and the rest crossing an enhanced network. A previous analysis of these data had allowed us to infer the longitudinal component of the magnetic field by applying the weak-field approximation (WFA) to the circular polarization profiles, and to assign the inferred magnetic fields to different layers of the solar atmosphere based on the results of previous theoretical radiative transfer investigations. In this work, we apply the recently developed TIC to the same data. We obtain a stratified model atmosphere that fits the intensity and circular polarization profiles at each position along the spectrograph slit and we compare our results for the longitudinal component of the magnetic field with the previously obtained WFA results, highlighting the generally good agreement in spite of the fact that the WFA is known to produce an underestimation when applied to the outer lobes of the Mg ii h and k circular polarization profiles. Finally, we use the inverted model atmospheres to give a rough estimation of the energy that could be carried by Alfvén waves propagating in the chromosphere in the plage and network regions, showing that it is sufficient to compensate for the estimated energy losses in the chromosphere of solar active regions.

Derivation of Instrument Requirements for Polarimetry Using Mg, Fe, and Mn Lines between 250 and 290 nm

“…That work requires a more complex approach of synthesizing spectra from known model atmospheres, degrading those spectra as if they were observed by a hypothetical instrument, and attempting to recover the model parameters through interpretation using the WFA or with inversion codes like DeSIRe (Ruiz Cobo et al 2022), STiC (de la Cruz Rodríguez et al 2019), or TIC (Li et al 2022). The Mg II lines have been studied and used for diagnostics of chromospheric magnetism in recent years (e.g., del Pino Alemán et al 2016;Manso Sainz et al 2019;Ishikawa et al 2021;Centeno et al 2022;Rachmeler et al 2022;Afonso Delgado et al 2023a;Li et al 2023). These efforts should be continued and expanded to include the Fe I and Fe II lines identified in this work.…”

Magnetic Field Information in the Near-ultraviolet Fe ii Lines of the CLASP2 Space Experiment

“…The application of the weak-field approximation (WFA) to the circular polarization profiles observed in the plage region allowed for the mapping of the longitudinal component of the magnetic field (B L ) across different layers of the solar chromosphere (Ishikawa et al 2021), extended to the photosphere with simultaneous observations by Hinode/SOT-SP (Kosugi et al 2007). Later, the application of the Tenerife inversion code (TIC; Li et al 2022) to the CLASP2 Stokes I and V profiles observed in the plage target allowed for the inference of a stratified model atmosphere, including its thermal, dynamic, and magnetic structure (Li et al 2023).…”