Spectroscopy of multiple-ionized atoms in solar and stellar investigations an vacuum ultraviolet region

The short review of contemporary state of spectroscopy of multiple-ionized atoms (MIA) in solar and stellar investigations in the lambda>=20A range is presented. Due to the observational material obtained at the space station ''Skylab'' and the progress in MIA laboratory investigations, one succeeded in deciphering many new forbidden lines. However there are still about 50 percent of lines in emission solar spectra which remain nonidentified. One of the methods of solving the problem is a thorough laboratory investigation of ion spectra of the spread in the sun elements considered to be sufficiently studied with application of nowadays high resolution spectral equipment. The other method is bound to the expressed by Edlen idea on a possible appurtenance of non- identified coronallines in the visible region to transitions from metastable levels of excited configurations which enables identifying almost all the coronal lines in the visible region. For the last time in astrophysics the diagnostic application of already identified lines, for example, determining of electron density by MIA spectra is successfully developed. Serious attention in astrophysical observations is given to the study of the form of s spectral lines. In the field of investigations of vacuum ultraviolet stellar spectra main limitation is low line intensity