Time , spatial , and spectral resolution of the H α line-formation region of Deneb and Rigel with the VEGA / CHARA interferometer

Context. BA-type supergiants are amongst the most optically-bright stars. They are observable in extragalactic environments, hence potential accurate distance indicators. Aims. An extensive record of emission activity in the Hα line of the BA supergiants βOrionis (Rigel, B8Ia) and α Cygni (Deneb, A2Ia) is indicative of localized time-dependent mass… (More)