Spectroscopic Monitoring of the 2017–2019 Eclipse of VV Cephei

Volume 48 number 2 (2020)

Download this article (pdf)

Ernst Pollmann

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

Philip Bennett

Department of Physics and Atmospheric Science, 6310 Coburg Road, Dalhousie University, Halifax, NS B3H 4R2, Canada; Philip.Bennett@dal.ca

Abstract

VV Cephei is an M supergiant star that eclipses its B-type companion every 20.36 years. It is the eponymous member of the red supergiant + hot main-sequence binaries known as the VV Cephei stars. The red supergiant primary is surrounded by a circumstellar shell due to mass loss via a slow, stellar wind, and this circumstellar material interacts with the hot companion. Spectroscopic observations in the ultraviolet indicate the presence of material accreting onto the hot star from the wind of the M supergiant primary, and the probable presence of an accretion disk around the companion. The hot star and disk produce a local H II “bubble” that results in very prominent Hα emission originating from the vicinity of the companion. In this work, we report on a continuing campaign of spectroscopic observations of Hα emission from VV Cep over the period 2015–2020 by amateur observers of the ARAS spectroscopy group. We also present a newly discovered 42-day period variability in the equivalent width of this Hα emission. NOTE: The authors of this article have posted a research update: https://app.aavso.org/jaavso/article/3845/