Speaker
Description
In this talk we aim at deepening our understanding of pores with particular focus on their characterization at middle atmospheric layers (upper photosphere / lower chromosphere). Pores are small and dark magnetic features observed in the photosphere that are composed of only an umbral core, i.e. they do not have penumbral structure, and have short lifetimes compared to larger sunspots. The absence of penumbra has been explained by a simple model: they are a magnetic flux tube whose magnetic field does not reach the inclination threshold required for penumbral formation. However, there are not many works addressing their vertical structure and thermodynamic coupling up to chromospheric heights. Understanding the stratification of physical parameters above pores is essential for clarifying how magnetic flux concentrations interact with the surrounding plasma, how energy is transported and dissipated, and how a magnetic canopy can develop above these structures.
Here we take advantage of the full spectropolarimetric capabilities of the SCIP instrument onboard the balloon mission Sunrise. The dataset corresponds to observations taken on 2024, July 10th between 19:14 UT and 21:05 UT, targeting a pore embedded in a flux emergence region. The simultaneous acquisition of spectral lines sensitive to both photospheric and chromospheric layers enables a consistent multi-height analysis of the atmospheric structure. We have inverted the observations in the Ca II 8542 Å spectral window using the coupled version of the STiC inversion code, which performs non-LTE inversions to retrieve the stratification of temperature, line-of-sight velocity, and the magnetic field vector from the photosphere up to the middle chromosphere (log τ ≈ −4.5). The coupled inversion scheme ensures a physically consistent solution across multiple spectral diagnostics, allowing us to infer vertical gradients and identify signatures of magnetic field expansion and thermodynamic structuring.
We investigate the thermal and magnetic structure of the pore in the upper photosphere and chromosphere and complement it with radiative losses in the Mg II and Ca II lines as well as determination of the excess thermal energy identified for mid-high photospheric temperature enhancements
Our results reveal an expansion of the magnetic field with height consistent with the development of a magnetic canopy. Thermodynamically, the pore is cooler at photospheric heights but presents similar temperatures at the mid-chromosphere. All around the pore boundary (as determined from intensity threshold) we infer temperature enhancements in the upper photosphere (up to 300K) that require approximately $5kJ/m^2$. This is likely a consequence of heating in the canopy boundary but, due to the observational setup, we could not determine the actual heating mechanism. These regions exhibit increased radiative losses mostly associated with the CaII.