Observation state of the campaign

VV Cep 2017-2019 Campaign
Moderator for this forum: Ernst Pollmann

Re: Observation state of the campaign

Postby Peter Somogyi » Sat Apr 07, 2018 8:18 pm

Hello Ernst,

Unfortunately, there is no voice file attached with that pdf on shelyak, and the pdf reads like an explicit model suggestion.
And, another document http://astrospectroscopy.de/media/files/SAS_2015.pdf: Fig.9 also detailing - another kind of - disk model, like an already known fact.
I'd suggest updating these easy-to-find pdf docs putting a red warning "2018.04.07: Disk model is in question" over these pictures.

- Peter
Peter Somogyi
Posts: 292
Joined: Sun Jul 13, 2014 8:56 am

Re: Observation state of the campaign

Postby Ernst Pollmann » Thu Apr 12, 2018 9:03 am

Dear colleagues,
I want offer for discussion the following thoughts concerning the V/R variability in VV Cep:
The investigations of Wright (1977) show that the H-alpha emission component is formed within the accretion environment of the B star, as an undisturbed, intrinsic single emission (dotted lines in the following Fig.).
Fig. 1.png
Fig. 1.png (157.9 KiB) Viewed 65 times

After Wright the entire binary system is enveloped of a cloud of neutral hydrogen, which produces in the observers line of sight, a central absorption line in the Halpha emission center. For this reason this emission appears split into two components, the V and the R components.
Because of the orbital movement of the B star around the M star (the following Fig., above, RV curve), the H-alpha emission barycenter naturally follows the radial velocity of the B star. In other words, the intrinsic single Halpha emission and its components V and R moves back and forth behind the central absorption line, which leads to a periodic change of the V and R intensities, which is exactly what we have observed in our long-term V/R monitoring (following Fig., bottom).
Fig. 2.png
Fig. 2.png (89.85 KiB) Viewed 65 times

But, the 43.7 day V/R period must have another cause. The bow-shock-front before the B star as consequence of the appox. 40 km/s supersonic movement of the star through the stellar wind of the M star, (postulated by Ph. Bennet) generates a pattern of longitudinal shock-waves in the flow of gas behind the shock-front, with corresponding periodic changes in the radial velocity.

https://de.wikibooks.org/wiki/Physik_Ob ... _Wellen_(Längswellen)

https://en.wikipedia.org/wiki/Shock_wav ... trophysics

These changes in RV are analogous to the long-term V/R changes mentioned above with the superimposed short-term period of 43.7 d in V/R. With this scenario, the phenomenon of the observed V/R variability can be explained much more reasonably than with the disk model of the past. Because Phil is informed, his comments on these considerations would be appreciated.

Ernst Pollmann
Ernst Pollmann
Posts: 291
Joined: Mon Sep 26, 2011 7:16 pm

Re: Observation state of the campaign

Postby Peter Somogyi » Fri Apr 13, 2018 5:22 am

Hello Ernst,

Looking at these graphs, H-alpha looks still rotational rather than coming from a bow shock: almost constant {height, width} of the approximated bell curve.
At least I would expect very different bell curves at phases {0, 0.25, 0.5, 1} (the random absorbtions appearing on top of the V peak can be ignored, that's a shortterm change I often saw in the UV end too).
But maybe you have better quality data from the recent decades to present here.

Peter Somogyi
Posts: 292
Joined: Sun Jul 13, 2014 8:56 am


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