  We have investigated the impact of the $^{14}N(p,\gamma)^{15}O$ reaction rate
recently redetermined by the LUNA experiment, on the shell H-burning and core
He-burning phases of low-mass, metal poor stellar models. The new reaction rate
has small but noticeable effects, the largest one being a $\sim$7-8\% reduction
of the red giant branch lifetimes. To different degrees, the lifetimes and
luminosities of horizontal branch models, the mass of the stellar models
evolving within the RR Lyrae instability strip, the luminosity of the red giant
branch luminosity function bump, the theoretical calibrations of the
R-parameter and tip of the red giant branch luminosity are also affected.
Predictions for the tip of the red giant branch luminosity, in particular, are
in very good agreement with the currently available empirical constraints.

Solar and Stellar Astrophysics