Multi-Wavelength Eclipse Observations of a Quiescent Prominence

Abstract

We construct the maps of temperatures, geometrical thicknesses, electron densities and gas pressures in a quiescent prominence. For this we use the RGB signal of the prominence visible-light emission detected during the total solar eclipse of 1 August 2008 in Mongolia and quasi-simultaneous Hα spectra taken at Ondřejov Observatory. The method of disentangling the electron density and geometrical (effective) thickness was described by Jejcic and Heinzel (Solar Phys. 254, 89 – 100, 2009) and is used here for the first time to analyse the spatial variations of prominence parameters. For the studied prominence we obtained the following range of parameters: temperature 6000 – 15 000 K, effective thickness 200 – 15000 km, electron density 5×109 – 1011 cm−3 and gas pressure 0.02 – 0.2 dyn cm−2 (assuming a fixed ionisation degree n p/n H=0.5). The electron density increases towards the bottom of the prominence, which we explain by an enhanced photoionisation due to the incident solar radiation. To confirm this, we construct a two-dimensional radiative-transfer model with realistic prominence illumination.