  A global disk oscillation implemented in the viscous decretion disk (VDD)
model has been used to reproduce most of the observed properties of the well
known Be star $\zeta$ Tau. 48 Librae shares several similarities with $\zeta$
Tau -- they are both early-type Be stars, they display shell characteristics in
their spectra, and they exhibit cyclic $V/R$ variations -- but has some marked
differences as well, such as a much denser and more extended disk, a much
longer $V/R$ cycle, and the absence of the so-called triple-peak features. We
aim to reproduce the photometric, polarimetric, and spectroscopic observables
of 48 Librae with a self-consistent model, and to test the global oscillation
scenario for this target. Our calculations are carried out with the
three-dimensional NLTE radiative transfer code HDUST. We employ a rotationally
deformed, gravity-darkened central star, surrounded by a disk whose unperturbed
state is given by the VDD model. A two-dimensional global oscillation code is
then used to calculate the disk perturbation, and superimpose it on the
unperturbed disk. A very good, self-consistent fit to the time-averaged
properties of the disk is obtained with the VDD. The calculated perturbation
has a period $P = 12$ yr, which agrees with the observed period, and the
behaviour of the $V/R$ cycle is well reproduced by the perturbed model. The
perturbed model improves the fit to the photometric data and reproduces some
features of the observed spectroscopic data. Some suggestions to improve the
synthesized spectroscopy in a future work are given.
