Sunspot Umbra Atmosphere from Full Stokes Inversion

Sunspots are prominent manifestations of the solar cycle and provide key constraints for understanding its operation. Also, knowing the internal structure of sunspots allows us to gain insights on the energy transport in strong magnetic fields and, thus, on the processes inside the convection zone, where solar magnetic fields are generated and amplified before emerging at the surface on various scales, even during solar minima. In this paper, we present results of a. spectropolarimetric analysis of a sunspot observed during the declining phase of solar cycle 23. By inversion of the full Stokes spectra, observed in several spectral regions in the optical at the THEM'S facility, we infer the height dependence of physical quantities such as the temperature and the magnetic field strength for different sunspot regions. The simultaneous use of atomic (Fe 1 5250.2 and 5250.6 angstrom) and highly temperature-sensitive molecular (TiO 7055 angstrom and MgH 5200 angstrom) lines allows us to improve a model of the sunspot umbra.