Stellar Wind Variability of Be Star FY CMA

Archival IUE spectra including the ultraviolet resonance lines and optical spectra of the Hα and the He i λ5876 A line of the Be star FY CMa show inverse P Cygni profiles, indicating an unusual activity in February 1987. The edge velocity measured in the blue-shifted absorption wings profile reached up to ~ −950 km s−1. We estimate the mass loss rate Ṁ to be about 4.1 × 10−9M⊙ yr−1 (assuming spherical symmetry). If we assume instead a conical wind shape, for a cone half angle of ~ 30°, Ṁ ≈ 3.4 × 10−10M⊙ yr−1, or Ṁ ≈ 2.2 × 1015 gm s−1. We attempt to give a qualitative explanation of the abrupt activity in FY CMA in terms of the infall of material.