H II regions are clouds of glowing, ionised gas associated with regions of recent star formation. By studying the light emitted by these regions, we can learn about their physical conditions and chemical composition, providing important clues about how stars and galaxies form and evolve. One of the key properties we need to know is the temperature of the gas. We can measure it from the emission lines of different chemical elements, which probe different parts of an H II region. However, it is not always possible to measure all these temperatures directly. In these cases, we need to estimate

Solar wavefront sensing has been a challenge for astrophysical instrumentalists, due to the low contrast between the Sun and the sky background compared to night-time observations, which limits the performance of adaptive optics systems. Wavefront correction in solar physics requires the analysis of extended images; meanwhile, at night the displacement of a punctual object is analysed. This technique limits the spatial resolution, and therefore the accuracy in the wavefront reconstruction. To solve this problem, a new method of direct wavefront sensing without the need for image formation