SIMBAD references

Optical imaging and long-slit spectroscopy of the planetary nebula (PN) surrounding the last thermal pulse object V4334 Sagittarii are presented. Using any reasonable distance consistent with the observed nebula reddening of E(B-V) =0.71 ±0.09, the physical dimensions, kinematics, abundances and ionized mass are typical of evolved planetary nebulae (PNe). With the most firmly established observational quantities, nebular photoionization models are constructed, which show that it is likely that some recombination has already occurred (if n_e ∼ 200 cm^–3). The models give good constraints on the surface temperature of the precursor [log (T_s/K) = 5.1±0.2], but not on its luminosity [log (L_s/L_☉) ∼ 3.3±1.3]. These results are only consistent with white dwarf cooling tracks if 0.546 < M< 0.836 M_☉ and give good agreement with the initial position for the test model of last thermal pulse evolution recently presented by Iben & MacDonald.