  By applying a relativistic mean-field description of neutron star matter with
density dependent couplings, we analyse the properties of two different matter
compositions: nucleonic matter with delta baryons and nucleonic matter with
hyperons and delta baryons. The delta-meson couplings are allowed to vary
within a wide range of values obtained by experimental data, while the
hyperon-meson couplings are fitted to hypernuclear properties. Neutron star
properties with no deconfinement phase transition are studied. It is verified
that many models are excluded because the effective nucleon mass becomes zero
before the maximum mass configuration is attained. Hyperon-free with
delta-dominated composition compact stars are possible, the deltic stars. It is
found that with a convenient choice of parameters the existence of deltic stars
with 80% of delta baryons at the center of the star is possible. However, the
presence of hyperons lowers the delta baryon fraction to values below 20% at
the center and below 30% at 2-3 saturation densities. It is discussed that in
the presence of delta baryons, the hyperon softening is not so drastic because
deltas couple more strongly to the $\omega$-meson, and the stiffness of the
equation of state is determined by the $\omega$-dominance at high densities.
The speed of sound reflects very well this behavior. The compactness of the
pulsar RX J0720.4-3125 imposes $x_{\sigma\Delta}>x_{\omega\Delta}>1$ and favors
$x_{\rho\Delta}>1$.
