The centre-to-limb variations of solar Fraunhofer lines imprinted upon lunar eclipse spectra

Variations in the sky brightness during a lunar eclipse

A total lunar eclipse is conjectured to have influence on the physical conditions of an environmental area, particularly on the brightness of the sky. The phenomenon might also be relevant on weather parameters change on Earth, such as temperature, humidity and pressure, though a straightforward correlation is not easy to establish. This work mainly aims at measuring the brightness of the sky a...

Oxygen lines in solar granulation II. Centre-to-limb variation, NLTE line formation, blends and the solar oxygen abundance

Context. There is a lively debate about the solar oxygen abundance and the role of 3D models in its recent downward revision. These models have been tested using high resolution solar atlases of flux and disk-centre intensity. Further testing can be done using centreto-limb variations. Aims. Using high resolution and high S/N observations of neutral oxygen lines across the solar surface we seek...

Speckle measurements of the centre-to-limb variation of the solar granulation

The Vacuum Tower Telescope (VTT) at the Observatorio del Teide/Tenerife was used to perform speckle observations of photospheric granulation from disc centre to limb at λ = 550 ± 5 nm. Images were reconstructed with the spectral ratio technique (von der Lühe 1984) and the speckle masking method (Weigelt 1977, Weigelt & Wirnitzer 1983, Lohmann et al. 1983). The granular rms contrast relative to ...

Solar eclipse safety.

An investigation of Fe emission lines in solar flare spectra

Previously, large discrepancies have been found between theory and observation for Fe  emission line ratios in solar flare spectra covering the 224–327 Å wavelength range, obtained by the Naval Research Laboratory’s S082A instrument on board Skylab. These discrepancies have been attributed to either errors in the adopted atomic data or the presence of additional atomic processes not included ...