PREDNASAJUCI / LECTURER : Július Koza (1) Astronomical Institute, Slovak Academy of Sciences, 059 60 Tatranská Lomnica NAZOV / TITLE : Temperature minimum region revealed ABSTRAKT / ABSTRACT : Temperature is the variable that most strongly controls the continuum and spectral line shapes and intensities yielded by the classical 1D semiempirical models of solar atmosphere. Their characteristic feature is a distinct temperature minimum separating the upper photosphere, dominated by the gas pressure, from the lower chromosphere where the magnetic field gains a dominance over the gas. High-resolution imaging spectroscopy taken off limb in the wing of the Hbeta line shows the dark intensity gap between the photospheric limb and chromosphere, which is absent in the Hbeta line-center images and also in the Ca II 854.2 nm images. We interpret the dark gap in the Hbeta line-wing images as a manifestation of the temperature minimum region between the photosphere and chromosphere. To support this hypothesis we calculate synthetic spectra of the off-limb Hbeta and Ca II 854.2 nm emissions with a dedicated non-LTE code based on Rybicki & Hummer's formalism in one-dimensional spherical geometry and find good agreement with the observations. The analysis of synthetic line profiles shows that the dark gap in the Hbeta line-wing images maps the temperature minimum region between the photosphere and chromosphere due to the opacity and emissivity gap of Balmer lines in this layer. We found that an increased microturbulence in the model chromosphere is needed to reproduce the dark gap in the outer line wing, suggesting that the observed high-contrast Hbeta gap is the manifestation of the temperature minimum and the dynamic nature of the solar chromosphere. The work opens a new window for studying the temperature minimum region by other lines of the Balmer series and with a more realistic chromospheric model atmosphere, which includes various dynamic phenomena relevant to the chromosphere.