Reversal-free CaIIH profiles: a challenge for solar chromosphere modeling in quiet inter-network - AstrophysicsReportar como inadecuado




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Abstract: We study chromospheric emission to understand the temperature stratificationin the solar chromosphere. We observed the intensity profile of the CaIIH linein a quiet Sun region close to the disk center at the German Vacuum TowerTelescope. We analyze over 10^5 line profiles from inter-network regions. Forcomparison with the observed profiles, we synthesize spectra for a variety ofmodel atmospheres with a non local thermodynamic equilibrium NLTE radiativetransfer code. A fraction of about 25% of the observed CaIIH line profiles donot show a measurable emission peak in H {2v} and H {2r} wavelength bandsreversal-free. All of the chosen model atmospheres with a temperature risefail to reproduce such profiles. On the other hand, the synthetic calciumprofile of a model atmosphere that has a monotonic decline of the temperaturewith height shows a reversal-free profile that has much lower intensities thanany observed line profile. The observed reversal-free profiles indicate theexistence of cool patches in the interior of chromospheric network cells, atleast for short time intervals. Our finding is not only in conflict with afull-time hot chromosphere, but also with a very cool chromosphere as found insome dynamic simulations.



Autor: R.Rezaei, J.H.M.J.Bruls, W.Schmidt, C.Beck, W.Kalkofen, R.Schlichenmaier

Fuente: https://arxiv.org/







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