International Observing Campaign: Photometry and Spectroscopy of P Cygni

摘要

In this combined campaign on the Luminous Blue Variable star P Cygni we are trying for the first time by way of contemporaneous measurements of photometric V brightness and Ha equivalent width (EW) to realize a longterm monitoring of the intrinsic Ha-line flux. The photometric observers of AAVSO and BAV (Germany) and a spectroscopic observer group (Japan, France, Spain, Germany) started observing for this campaign in November 2008 at the request of Bernd Hanisch and one of us (EP) in order to continue former investigations whose results were based on multi-daily averaging of V and EW. Additional data from literature enable us to represent the quantitative behavior of the Ha-line flux for the timespan August 2005 to December 2011, which behavior reflects variabilities in mass-loss rate, stellar wind density, and ionization structure.