A Detailed Study of the C IV lambda 1550 Line Profile and Adjacent Spectral Features in NGC 4151 from 1978 to 1983
Perola, G. C.; Altamore, A.; Boksenberg, A.; Penston, M. V.; Snijders, M. A. J.; Bromage, G. E.; Clavel, J.; Elvius, A.; Ulrich, M. H.; Pelat, D.
Netherlands, Spain, Italy, United Kingdom, Sweden
Abstract
The 1450 - 1720 Å spectral region of NGC 4151 is analyzed by means of Gaussian decomposition for 69 different epochs, from early 1978 to the end of 1983. The C IV λ1550 emission profile is well represented by a core, whose full width at half-maximum varies between 2600 and 5500 km s-1, and an ultrabroad component (14,600 km s-1). The variations of the ultrabroad feature suggest that it originates in a region whose "radius" is ≡5 lt-day. The analysis of lines from He II, C III], N IV] and O III] indicates the presence of two additional discrete broad line subregions. A study of the velocity dispersions indicates that the motion of the gas is Keplerian and yields a value of (3.7±0.5)×107M_sun; for the central mass. A correlation is found between the wavelength of the ultrabroad C IV λ1550 component and its intensity. It strongly suggests the existence of a decelerated outflow whose velocity is 4000 km s-1 at 5 lt-day from the nucleus.