A FIVE-YEAR SPECTROSCOPIC AND PHOTOMETRIC CAMPAIGN ON THE PROTOTYPICAL alpha CYGNI VARIABLE AND A-TYPE SUPERGIANT STAR DENEB

作者：Richardson N D^*; Morrison N D; Kryukova E E; Adelman S J

来源：Astronomical Journal, 2011, 141(1): 17.

DOI：10.1088/0004-6256/141/1/17

• stars: early-type
• stars: individual (Deneb)
• stars: mass-loss
• stars: variables: general
• supergiants

Deneb is often considered the prototypical A-type supergiant and is one of the visually most luminous stars in the Galaxy. A-type supergiants are potential extragalactic distance indicators, but the variability of these stars needs to be better characterized before this technique can be considered reliable. We analyzed 339 high-resolution echelle spectra of Deneb obtained over the five-year span of 1997 through 2001 as well as 370 Stromgren photometric measurements obtained during the same time frame. Our spectroscopic analysis included dynamical spectra of the H alpha profile, H alpha equivalent widths, and radial velocities measured from Si II lambda lambda 6347, 6371. Time-series analysis reveals no obvious cyclic behavior that proceeds through multiple observing seasons, although we found a suspected 40 day period in two, non-consecutive observing seasons. Some correlations are found between photometric and radial velocity data sets and suggest radial pulsations at two epochs. No correlation is found between the variability of the H alpha profiles and that of the radial velocities or the photometry. Lucy found evidence that Deneb was a long-period single-lined spectroscopic binary star, but our data set shows no evidence for radial velocity variations caused by a binary companion.

• 出版日期2011-1