Simultaneous EXOSAT-IUE observations of NGC 4151
Tarenghi, M.; Piro, L.; Perola, G. C.; Altamore, A.; Boksenberg, A.; Penston, M. V.; Snijders, M. A. J.; Bromage, G. E.; Clavel, J.; Elvius, A.; Ulrich, M. H.; Pettini, M.
Italy, United Kingdom, France, Sweden, Spain
Abstract
NGC 4151 was observed four times in Nov. 83. The results indicate that: a) there exists a correlation between the X-ray and UV fluxes on the long term; b) the soft X-ray excess between 0.1 and 1 keV is probably steeper than expected from the leaky absorber model by Holt et al (1980); c)the spectral fit to the ME data, after correction for a soft component, yields α=1,73±0.27, NH=(15.2±2.2)×1022 cm-2, E.W.(Fe line)=0.208±0.084 keV, and does not require a strong overabundance of Fe in the absorber. The relationship between NH and the strength of the broad emission lines is commented.