Period Analysis of the Radial Velocity in Pleione

A period analysis of the radial velocities of the shell lines in Pleione (B8e) was performed. We obtained a period of 218.0 days by combining the data in two successive shell phases. The orbital elements derived from the resulting velocity curve are: the eccentricity, e = 0.60; the semi-amplitude, K1 = 5.9 km s⁻¹; the semi-major axis, a1 sin i = 20R⊙ and the mass function, ƒ(M) = 2.4·10⁻³M⊙. The secondary is most probably a low-mass dwarf, though we retain the possibility of a helium star or white dwarf. After examining the mass-loss rate from helium stars, we concluded that the circumstellar gas around the B8 primary is supplied from the primary, itself.