Spectra of Be Star Delta Scor / 7 Sco
A recent observation of Be-Star Delta Scopii or arabic name Dschubba.
This star with a appearant brightness of currently 2.3mag is about 150pc away. Dschubba is a binary system, further components are suspected but not confirmed. The main component is a B0.3 IV star about 14.000 brighter than and 5 times larger than the sun. It's variable, in the year 2000 it's brightness raises up to 1.6mag. This increase is related to the development of a surrounding disc. It's assumed that the disc still exists. It rotates with about 180 km/s which is about 70 percent of the critical velocity.
The compangion is of spectral type B3 orbits in 10 years at a distance of about 10 astronomical units. It's rougly 10 times less bright.
Both star are in the phase of burning Hydrogen to Helium. The main component might develop in the next million years to a giant like Antares and because of about 16 solar masses will mostlikely performis a supernova.
Recent analysis of kinematic using spectra as well as GAJA-data indicates the the groups around Dschubba triggered a sequence of star formation moving through the groups around the upper scorpion towards rho Ophiuchus as youngest and closest star formation region.
Sources:
Jim Kaler, http://stars.astro.illinois.edu/sow/dschubba.html
Meiland A. et al, Astronomy & Astrophysics, Volume 532 (2011), https://ui.adsabs.harvard.edu/abs/2011A%26A...532A..80M/abstract
N. Miret-Roig et al., A&A 667, A163 (2022), https://www.aanda.org/articles/aa/full_html/2022/11/aa44709-22/aa44709-22.html
