There are still several secrets about the Solar corona that astronomers must unveil. The corona is the uppermost solar atmosphere, made by low-density gas with temperatures as high as a few million degrees (as a comparison, the plasma in photosphere and chromosphere is at about 5600 K and 10000 K, respectively). The energy required to heat the gas up to
In the last years several observational surveys were designed in order to detect stellar mass black holes, including both those which are actively accreting and black holes in a quiescent status. These observations are crucial to understand the real extent of the population of black holes in the Milky Way, and to understand the formation of massive stellar black holes
