Astronomy and astrophysics vol:242 issue:2 pages:433-442
The variability of the peculiar post-AGB star HR 4049 is investigated. The data are 250 photometric observations in the Geneva system, most of which were taken during seven subsequent seasons, near-infrared photometry taken during one season, a few IUE spectra, and some spectroscopic data that are randomly distributed in time. The optical photometry reveals a period of 434 days; the amplitude is inversely proportional to the wavelength. The 434-day period is also distinctly present in the 20 radial velocities we recorded for the star.