A quiescent prominence was observed by several instruments on 2007 April 25. The temporal evolution was recorded in Hα by Hinode/SOT, in X-rays by Hinode/XRT and in the 195Å channel by TRACE. Moreover, ground-based observatories (GBO) provided calibrated Hα intensities. Simultaneous EUV data were also taken by the Hinode/EIS and SOHO/SUMER-CDS spectrometers. Here we have selected the SOT Hα image taken at 13:19 UT which nicely shows the prominence fine structure. We compare this image with co-temporal ones taken by XRT and TRACE and show the intensity variations along several cuts parallel to the solar limb. EIS spectra were obtained about half an hour later. Dark prominence structure clearly seen in the TRACE and EIS 195Å images is due to the prominence absorption in HI, HeI and HeII resonance continua plus the coronal emissivity blocking due to the prominence void (cavity). The void clearly visible in XRT images is entirely due to X-ray emissivity blocking, since no prominence structure is seen in the XRT images because of negligible absorption at X-ray wavelengths. We use TRACE, EIS and XRT data to estimate the amount of absorption and blocking. Independently, the Hα integrated intensities provide us with an estimate of the Hα opacity and this is related to the opacity of resonance continua as follows from the non-LTE radiative-transfer modeling. Therefore, we have an independent check of the results obtained from TRACE/XRT and EIS/XRT. However, spatial averaging of the Hα and EUV data have quite different natures which must be taken into account when evaluating the true opacities. We demonstrate this important effect here for the first time. Finally, based on this multi-wavelength analysis, we discuss the determination of the column densities and the ionization degree of hydrogen in the prominence.

Aims. The aim of this work is to analyse the multi-instrument observations of the June 22, 2010 prominence to study its structure in detail, including the prominence-corona transition region and the dark bubble located below the prominence body. Methods. We combined results of the 3D magnetic field modelling with 2D prominence fine structure radiative transfer models to fully exploit the available observations. Results. The 3D linear force-free field model with the unsheared bipole reproduces the morphology of the analysed prominence reasonably well, thus providing useful information about its magnetic field configuration and the location of the magnetic dips. The 2D models of the prominence fine structures provide a good representation of the local plasma configuration in the region dominated by the quasi-vertical threads. However, the low observed Lyman-α central intensities and the morphology of the analysed prominence suggest that its upper central part is not directly illuminated from the solar surface. Conclusions. This multi-disciplinary prominence study allows us to argue that a large part of the prominence-corona transition region plasma can be located inside the magnetic dips in small-scale features that surround the cool prominence material located in the dip centre. We also argue that the dark prominence bubbles can be formed because of perturbations of the prominence magnetic field by parasitic bipoles, causing them to be devoid of the magnetic dips. Magnetic dips, however, form thin layers that surround these bubbles, which might explain the occurrence of the cool prominence material in the lines of sight intersecting the prominence bubbles.

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