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.
in order to inform about the progress of the campaign, here the current state of observation.
To clarify the meaning and objectives of this campaign, here the long-term monitoring of the overall profile development from April 2005 to June 2016. A detailed description can be found in:
What are the consequences of such emission?