VV Cephei up-to-date

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

VV Cephei up-to-date

Postby Ernst Pollmann » Sat Feb 23, 2019 10:03 am

Dear colleagues,
the spectroscopic observations and its results are up dated.
See:
http://astrospectroscopy.de/media/files ... todate.pdf

Ernst Pollmann
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Re: VV Cephei up-to-date

Postby Ernst Pollmann » Mon Jun 10, 2019 8:54 am

Dear colleagues,
here I want to present the current state of observation results of VV Cep.
On the basis of these results, in collaboration with Phil Bennett a new geometrically structure of the emission sources have been developed. This first draft is available as animation (30MB). In case of certain interest please write an email, I will send the password access to the cloud.
vvcep_1.png

vvcep_2.png
vvcep_2.png (597.67 KiB) Viewed 713 times


Ernst Pollmann
Ernst Pollmann
 
Posts: 337
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Re: VV Cephei up-to-date

Postby Ernst Pollmann » Tue Jun 18, 2019 7:16 am

Dear colleagues,
the gravitational force of the M supergiant exerts a forced angular momentum on the B star disk that triggers the 45-day precession period of the disk rotational axis. But a precessing disk rotation axis with a period of 45 days, would inevitably have to result in a simultaneous variation of radial velocity of the V(max) flux. Precise radial velocity (RV) measurements of the Hα V component, based on LHIRES III spectra of the ARAS observers (Schwarz, Kalbermatten, Bryssinck, Foster, Bertrand, Sawicki, Martin, Stiewing, Pollmann) seem to confirm the periodic precession movement of the B star disk rotational axis.

The first signs of such a movement have been discovered during the period analysis of the flux and EW time behavior of the Hα V and R components. Because of the small average RV amplitude of approx. (+/-) 1.7 km/s, this is not as simple as it seems. In spite of the high accuracy in wavelength calibration (order 10-3 to 10-4 Angströms) by using the new program SpectroCalc (developed by M. Schwarz, Austria), the error in RV is in the range of (+/-) 3 km/s in one observation night. All spectra have been calibrated with metal lines of the M star around Hα:

FeI 6546.245
TiI 6556.066
CaI 6572.781
FeI 6593.878

This method of calibration led to a radial velocity relative to the M star and without any influence of the system velocity. But the period of approx. 51 days still is unclear at this time, compared to 45 days found in analysis of the precession period of the disk rotational axis.
The upper plot shows the monitoring of RV measurements from 220 spectra from January 2018 to June 2019. The period analysis of the detrended RV data (in the upper plot) shows the plot in the middle, and finally the phase diagram of the found period of 50.9 days is shown in the plot bottom.
To better understand the RV of the V(max) flux, I recommend looking at the orbital animation, which I can send upon request.
conclusion.png
conclusion.png (238.23 KiB) Viewed 626 times

Ernst Pollmann
Ernst Pollmann
 
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Re: VV Cephei up-to-date

Postby Ernst Pollmann » Sun Jul 14, 2019 4:29 pm

Dear colleagues,
the current state of the ARAS campaign observation results seems to explain the periodic time behavior of the equivalent width and the flux of the Halpha emission components V & R.
See:
https://astrospectroscopy.de/News

Ernst Pollmann
Ernst Pollmann
 
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Re: VV Cephei up-to-date

Postby Joan Guarro Flo » Sun Jul 14, 2019 9:03 pm

Hallo Ernst,

Many thanks for your explanations, I'm going to observe this star.

Friendly, Joan.
Joan Guarro Flo
 
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Re: VV Cephei up-to-date

Postby Ernst Pollmann » Thu Sep 19, 2019 3:14 pm

Dear colleagues,
a lot of new spectra did enable an up date of the "state of the art" of VV Cep. See:
https://astrospectroscopy.de/News

Many thanks to all the colleagues who contributed with their spectra:
more than 900 for V and R analysis !!
more than 280 for Radial velocity analysis !!

Ernst Pollmann
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Posts: 337
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