How a Precessional Oscillation Ceases: Observational Evidence for the Dissolution of the Circumstellar Disk of Pleione

Volume 54 number 1 (2026)

Download this article (pdf)

Ernst Pollmann

Emil-Nolde-Str. 12, 51375 Leverkusen, Germany; ernst-pollmann@t-online.de

Abstract

Observational evidence presented in this article confirms recent theoretical predictions that sustained tidal forcing leads to disk warping, splitting into inner and outer components, and eventual dissipation of the outer disk. The morphology of the line profiles indicates a recurrent, tidally induced tilt of the circumstellar disk by approximately 30°. This scenario is directly confirmed in the present article. In particular, the exponential decay and ultimate disappearance of the orbital modulation in the Hα central absorption demonstrate the physical dissolution of the detached outer disk. These observations document, for the first time, the extinction of a tidally driven precessional oscillation in a Be-star disk.