Line-profile variation in tau Herculis

Abstract

Based on a time series of high-resolution spectra at He I lambda 4471 and Mg Ii lambda 4481, we have detected the line-profile variation of tau Her, one of the newly discovered Slowly Pulsating B Stars by Hipparcos. A period analysis has been performed for the radial velocities of Mg Ii lambda 4481. A best estimated period of 1.17 d or its one-day alias 0.536 d is different from its photometric period (1.25 d) derived from the Hipparcos mission.