HeI 6678 V/R periodicity in gamma Cas

Ernst Pollmann

I am presently reactivating the investigation of HeI 6678 V/R periodicity in gamma Cas.

Stee et al. (1998) proposed that the He excitation and ionization region, responsible for the emission in the HeI 6678 line, extends to 2.3 stellar radii. Thus, the HeI 6678 line has an important diagnostic value of activity close to the stellar surface.

The time-dependent mass loss from the primary component of the gamma Cas binary system assumes that both photospheric and disk density variations lead to the double peak profile variations of HeI 6678.

The attached overview shows the V/R periodicity of the Hel 6678 double-peak emission for the period August 2009 to September 2019. The period analysis of the V/R data of that time section cannot confirm the period, published at IBVS 6103 (2014), probably because of the few data available until 2014.

The 448 day period found today, is based on a much longer monitoring time and a three times larger data set, from the data bases BAA, BeSS and my own spectra. It would be great if interested observers would be willing to take part in this area of Be star research. The spectral resolution should be better than 10000. Please wright me an email in case of any questions.


Ernst Pollmann
Bovenaan Onderaan