Validating post-AGB candidates in the LMC and SMC using SALT spectra
  We selected a sample of post-AGB candidates in the Magellanic Clouds on the
basis of their near- and mid-infrared colour characteristics. Fifteen of the
most optically bright post-AGB candidates were observed with the South African
Large Telescope in order to determine their stellar parameters and thus to
validate or discriminate their nature as post-AGB objects in the Magellanic
Clouds. The spectral types of absorption-line objects were estimated according
to the MK classification, and effective temperatures were obtained by means of
stellar atmosphere modelling. Emission-line objects were classified on the
basis of the fluxes of the emission lines and the presence of the continuum.
Out of 15 observed objects, only 4 appear to be genuine post-AGB stars (27\%).
In the SMC, 1 out of 4 is post-AGB, and in the LMC, 3 out 11 are post-AGB
objects. Thus, we can conclude that the selected region in the colour-colour
diagram, while selecting the genuine post-AGB objects, overlaps severely with
other types of objects, in particular young stellar objects and planetary
nebulae. Additional classification criteria are required to distinguish between
post-AGB stars and other types of objects. In particular, photometry at far-IR
wavelengths would greatly assist in distinguishing young stellar objects from
evolved ones. On the other hand, we showed that the low-resolution optical
spectra appear to be sufficient to determine whether the candidates are
post-AGB objects.
