The Behavior of Bp He-weak Stars in the Far UV-Paper XIII: HD 161480

The analysis of four spectra of the B7 He-weak star HD 161480 recorded by the SWP camera on board the International Ultraviolet Explorer reveals instances of variations of the far ultraviolet spectral energy distribution shortwards of 1800 Å in spectra collected over 4 consecutive days with identical exposure times. The Si II doublet near 1530 Å is stronger at phase of FUV minimum. The C IV doublet at 1550 Å is absent. These variations suggest that silicon and other chemical elements are probably distributed in an inhomogeneous manner over the surface of HD 161480. The radial velocity of the Si II doublet varies over the 4 days observation, reflecting the orbital motion of this SB1 star.