Context :

Aims : We continue our study of the physical properties of the recurrent nova T Pyx , focussing on the structure of the ejecta in the nebular stage of expansion during the 2011 outburst .

Methods : The nova was observed contemporaneously with the Nordic Optical Telescope ( NOT ) , at high resolution spectroscopic resolution ( R \approx 65000 ) on 2011 Oct. 11 and 2012 Apr .
8 ( without absolute flux calibration ) , and with the Space Telescope Imaging Spectrograph ( STIS ) aboard the Hubble Space Telescope , at high resolution ( R \approx 30000 ) on 2011 Oct. 10 and 2012 Mar .
28 ( absolute fluxes ) .
The NOT spectra cover 3800-7300Ã , the HST spectra from 2011 Oct. cover 1150-5700Ã Â while the 2012 Mar .
spectrum covers 1150-1700Ã .
We use standard plasma diagnostics ( e.g .
[ O III ] and [ N II ] line ratios and the H \beta line fluxes ) to constrain electron densities and temperatures .
Using Monte Carlo modeling of the ejecta , we derive the structure and filling factor from comparisons to the optical and ultraviolet line profiles .

Results : The ejecta can be modeled using an axisymmetric conical – bipolar – geometry with a low inclination of the axis to the line of sight , i = 15 \pm 5 degrees , compatible with published results from high angular resolution optical spectro-interferometry .
The structure is similar to that observed in the other short orbital period recurrent novae ( e.g .
CI Aql , U Sco ) and RNe candidate KT Eri during their nebular stages .
We show that the electron density scales as t ^ { -3 } as expected from a ballistically ejected constant mass shell ; there is no need to invoke a continuing mass outflow following the eruption .
The derived mass for the ejecta with filling factor f \approx 3 \% , M _ { ej } \approx 2 \times 10 ^ { -6 } M _ { \odot } is similar to that obtained for other recurrent nova ejecta but inconsistent with the previously reported extended optically thick epoch of the explosion .
We suggest that the system underwent a common envelope phase following the explosion that produced the recombination event .
Implications for the dynamics of the recurrent novae are discussed .

Conclusions : The compact recurrent novae can be understood within a single phenomenological model with bipolar , although not jet-like , low mass ejecta .