1996A&A...310..923L

We have performed a spectroscopic monitoring of the F5I "post-AGB" star SAO 96709 on the Hα and NaD spectral regions in order to study atmospheric motions that could be associated with shock wave propagation throughout the stellar atmosphere. Twenty-one Hα spectra and seventeen NaD spectra were obtained as regularly as possible, over a 14 month interval. We find that the Hα, NaD, and other line profiles are strongly variable on a timescale of a few days. The 5853.688A BaII and 6587.622A CI lines also reveal a variation in their radial velocities. Fourier analysis of these variations yields one main period of 27.3 days and three secondary ones of 32.9, 11.9 and 7.1 days. The Hα profiles and the velocity variations are good evidence for complex atmospheric dynamics that are related to shock wave propagation throughout the atmospheric layers. These observed spectral features are in good agreement with the recently found photometric variability and point to a pulsating nature for SAO 96709 = HD 56126 = IRAS 07134+1005.