Optical and infrared observations of four suspected proto-planetary objects.

New observations of the suspected protoplanetary objects Hen1044, Hen1191, Hen1379, and OH/IR17.7-2.0 are presented. In the near-IR, Hen1191 and Hen1379 are irregularly variable while OH/IR17,7-2.0 might be variable with a period of about 800 days. Hen1044 shows no evidence of variability. The energy distributions of the sources are dominated by dust emission in the range 5-60 microns. Silicate grains are seen in their dust shells. Emission lines of increasing excitation are seen in Hen1379, Hen1191, and Hen1044. H-alpha profiles of Hen1191 and Hen1379 are used to estimate their radial velocities and the expansion velocities of their circumstellar shells. The objects are interpreted to be in stages intermediate between the asymptotic giant branch and the PN stage.