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
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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 262 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 262 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
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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.

Cheers,
Peter
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Re: Observation state of the campaign

Postby Ernst Pollmann » Tue Jun 26, 2018 3:14 pm

Dear colleagues,
after a long break here an information to the current state of our joint monitoring. How the variations of EW (plot top) and V/R (plot bottom) are to understand, we want to describe soon in a corresponding publication. Until then I ask still for some patience.
EW & VtoR.png
EW & VtoR.png (127.4 KiB) Viewed 90 times

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