spectro-aras.com

Dear colleagues!
The He1 6678 double peak emission in the spectrum of the Be star delta Sco, has an enormous diagnostic importance in terms of the development of the disk around the primary star.
With this in mind, the attached spectral sequence shows interesting, drastic changes beginning with the familiar emission profile in April 2018, continuing with a very weak, pronounced emission embedded within the photospheric rotational profile in August 2019, followed afterwards by slow development again toward a double peak emission in April 2020.
The period of visibility of delta Sco this year has begun and I want to start a collaborative observation campaign to monitor this further development. This type of campaign might be interesting considering the coming periastron passage in May 2022.
It would be great if interested observers would contribute spectra of R>10000. Ernst Pollmann

Dear colleagues,
don´t forget the periastron passage of delta Sco next year.
The RV monitoring campaign has been started already. Ernst Pollmann

Dear colleagues,
observation to monitore the radial velocity while periastron in April 22-26 are urgently required. Ernst Pollmann

Dear colleagues,
the descent of the Halpha radial velocity does have started.
Please take spectra of the star for determination of the periastron time.
Ernst Pollmann