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Deneb is often considered the prototypical A-type supergiant, and is one ofthe visually most luminous stars in the Galaxy. A-type supergiants arepotential extragalactic distance indicators, but the variability of these starsneeds to be better characterized before this technique can be consideredreliable. We analyzed 339 high resolution echelle spectra of Deneb obtainedover the five-year span of 1997 through 2001 as well as 370 Stromgrenphotometric measurements obtained during the same time frame. Our spectroscopicanalysis included dynamical spectra of the H-alpha profile, H-alpha equivalentwidths, and radial velocities measured from Si II 6347, 6371. Time-seriesanalysis reveals no obvious cyclic behavior that proceeds through multipleobserving seasons, although we found a suspected 40 day period in two,non-consecutive observing seasons. Some correlations are found betweenphotometric and radial velocity data sets, and suggest radial pulsations at twoepochs. No correlation is found between the variability of the H-alpha profilesand that of the radial velocities or the photometry. Lucy (1976) found evidencethat Deneb was a long period single-lined spectroscopic binary star, but ourdata set shows no evidence for radial velocity variations caused by a binarycompanion.

A Five-year Spectroscopic and Photometric Campaign on the Prototypical alpha Cygni Variable and A-type Supergiant Star Deneb