Barium is one of
thermonuclear s - processes product in stars and its overabundance is
observed in CH subgiants, characterized by enhanced Sr and Ba lines,
and in metal deficient barium stars, giants showing overabundance of
s-processes elements (Sleivyté &
Bartkevicius 1995). Barium lines are present in solar and stellar
spectra. E.g. Komarov
Basak (1993) have found Ba I and Ba II lines in the spectra of the Sun
and of two Praesepe's stars (for Solar barium lines see also Anders 
Grevesse 1989).
Barium lines are also of interest
for the investigation of laboratory plasmas. Since the research of
Aulehla 
Herman (1958) who have determined neutral barium Stark effect
constants by investigating metallic lines broadened by an intermolecular
field, Stark broadening of Ba I and Ba II lines has been considered
experimentally and theoretically in a number of articles. Kato et al.
(1984) investigated wavelength shifts of Ba I and Ba II lines emitted by an
inductively coupled plasma. Manning et al. (1990) performed a study of
the effect of pressure and electron density on wavenumber position for
Ba II lines. Experimental Stark broadening parameters for ionized
barium lines of Jaeger (1969),
obtained with the help of a discharge sliding along the surface of a
liquid jet, Puric & Konjevic (1972), where the plasma source was a
T-tube, Hadziomerspahic et al. (1973, superseeding according to
Konjevic & Wiese 1976, the similar work of Platisa et al. 1971),
with Z-pinch as the experimental apparatus, and of Fleurier et al.
(1987), provided with a plasma jet, have been critically reviewed in
Konjevic & Wiese (1976) and Konjevic et al. (1984b).
Stark widths
of Ba II lines have been calculated by Cooper & Oertel (1967) within
the semiclassical approach taking into account hyperbolic classical
perturber paths and lower level broadening. For Ba II 1, 2, 3, and 4
multiplet they give full width at half maximum (FWHM) values of
0.42 Å, 0.84 Å, 1.02 Å and 1.20 Å respectively, but
without the electron temperature specified. Theoretically, Ba I lines
have been investigated by Grechikhin (1969), considering their
applicability to plasma diagnostics. Ba I and Ba II lines have been
considered theoretically as well by Davis (1972), for research of a
laser - generated barium plasma and, Ba II lines by Sahal-Bréchot
(1969b) within the semiclassical - perturbation formalism and by
Fleurier et al. (1977) within the same formalism but with the effect of
Feshbach resonances included. The semiclassical calculations by using
the theoretical approach developed by Griem et al. (1962) and further
improved and described in detail by Jones et al. (1971) and Griem
(1974), were performed by Puric et al. (1978).
For
Ba II 6s
S - 6p
P
multiplet, at an electron density of 
= 10
cm
and
electron
temperature T=15000 K, they obtain FWHM 
Å. In
Konjevic & Wiese (1976) and Konjevic et al. (1984b) the theoretical
comparison data have been calculated by W.W. Jones (private
communication in Konjevic & Wiese 1976), by using the same method.
Stark broadening parameters of Ba II mult. 1 and 2, for T = 16000 K
have been calculated also by Gorchakov & Demkin (1978) within the
semiclassical approach of Vainshtein & Sobel'man (1959). Griem's
(1968) semiempirical formula has been
applied to Ba II lines in Hadziomerspahic et al.
(1973), Fleurier et al.
(1977) and Dimitrijevic &
Konjevic (1981). Moreover,
Dimitrijevic & Konjevic (1981)
performed for Ba II 6s
S - 6p
P
multiplet 1, linewidth calculations within the modified
semiempirical method (Dimitrijevic & Konjevic
1980) and within the same approach but
with the Gaunt factor derived from the work of Younger
& Wiese (1979) for the perturbing
transitions without the change of the principal quantum
number, Lakicevic (1983) estimated
line widths and shifts for Ba I 6s
S - 6p
P
and Ba II
6s
S - 6p
P
multiplet for T =
20000 K, on the basis of the Stark broadening parameter dependence on the ionization
potential from the lower level of the corresponding transition. By using
Ba II 4899.9 Å and 4524.9 Å lines as example, Dimitrijevic & Popovic
(1989) demonstrated a simple method (developed for neutrals
by Vitel et al. 1988), suitable for
critical evaluation of existing data and interpolation
of new Stark widths along homologous sequences, by using a normalization factor for analogous transitions.
In order to continue our research of
Stark broadening parameters needed for the investigation of
astrophysical and laboratory plasmas and to provide the needed
Stark broadening data, we have calculated
within the semiclassical-perturbation formalism (Sahal-Bréchot 1969a,b)
electron-, proton-, and ionized helium-impact line widths and shifts for
14 Ba I and 64 Ba II multiplets. A summary of the
formalism for neutral emitters is given in Dimitrijevic 
Sahal-Bréchot (1984), and for ionized emitters
in Dimitrijevic et al.
(1991) and Dimitrijevic 
Sahal-Bréchot (1996). We note here that the inelastic collision
contribution is included in the ion-impact line widths.