Long-term campaign of del Sco

Long-term campaign of del Sco

Postby Ernst Pollmann » Fri Aug 17, 2018 8:45 am

Dear colleagues,
after the last Halpha EW maximum (JD 2453611), the disk activity of the Be-Star delta Sco seems to be to tire. This is particularly evident in the long-term stagnant EW of the He I 6678 double peak emission since JD 2456000. Actually, I had hoped for the opposite, because I had the intention to study the the tripple-peak phenomenon of the He I 6678 emission closer.
This does not seem possible for the next few years due to the slow activities in the photospheric area, i.e. very close of the central star, and of the associated lack of disk feeding.
delsco.png
delsco.png (168.53 KiB) Viewed 384 times

For those, who wants to know more about triple-peak-profile of the He I678 emission, see:

http://astrospectroscopy.de/media/files/BSN_He6678.pdf
http://astrospectroscopy.de/media/files/IBVS_6179.pdf

Ernst Pollmann
Ernst Pollmann
 
Posts: 313
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Re: Long-term campaign of del Sco

Postby Ernst Pollmann » Mon Aug 20, 2018 3:00 pm

Dear colleagues,
as continuation of my investigation of the link between the HeI6678 and Halpha emission strenght in delta Sco, here a further evaluation of the current data available at the BeSS data base.

During each periastron (period = 10.8 years) some ring material may flow from the primary’s Roche lobe into the secondary’s Roche lobe. During that process the disk becomes denser and single-, double- or triple peak profiles may be observable.

Outside of each periastron the He6678 line is emitted in an extended rotating elliptical disk or ring around the central star, where the ring is not centered on the central star. The situation might be more complex since the companion is triggering the disk/ring formation or destruction through tidal effect on the circumstellar disk/ring.
Halpha_HeI6678.png
Halpha_HeI6678.png (201.45 KiB) Viewed 330 times


There seems to be two physical effects going on in δ Sco: one is the ejection of material from the photosphere, the other is the formation of “blobs” of gas in the disk or ring(s) probably from viscosity effects. The blobs rotate in a more or less Keplerian mode, eventually to fall back closer to the star (Miroshnichenko, personal communication 07/2004).

Comments are welcome!

Ernst Pollmann
Ernst Pollmann
 
Posts: 313
Joined: Mon Sep 26, 2011 7:16 pm


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