New Results of VV Cep

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

New Results of VV Cep

Postby Ernst Pollmann » Fri Jul 01, 2022 6:45 pm

Dear colleagues,
herewith I want inform you about the newest evaluation of VV Cep. The growing data set since approx. JD 2459000 did enable a new analysis of the radial velocity of the V emission component.
The question has been, whether the former precession period of 52 day could be improved. See the attached analysis.
Many thanks for your worthwhile spectra!!
New_Results_of_VV_Cephei.png

Ernst Pollmann
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Re: New Results of VV Cep

Postby Ernst Pollmann » Sat Aug 06, 2022 7:42 am

For VV Cep interested observer:
Supplementary Intermediate Report (July 2022) to the Spectroscopic Monitoring of the 2017–2019 Eclipse of VV Cephei

https://app.aavso.org/jaavso/article/3845/

Ernst Pollmann
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Re: New Results of VV Cep

Postby Ernst Pollmann » Mon Sep 26, 2022 1:42 pm

Dear colleagues!
With the video links below I would like to explain what it is currently about at the VV Cep observation campaign.
The previous multi-year campaign had revealed that the B companion star, with its emitting accretion disk and emission ejections in the star's rotational axis, is subject to a periodic libration on its orbit around the M supergiant. A 40-50 day periodicity was indicated.

However, there was a lack of unmistakable clarity.
The current campaign aims to make this periodicity clear. The (total) Halpha-equivalent width (EW) of the tumbling disk, plus the emission ejections in both directions of the stellar rotation axis, should be a suitable parameter to clearly represent this periodicity.

The video animation "Orbit B-Star" shows schematically the libration of the B star with its accretion disk and emission ejections on the orbit:
https://www.dropbox.com/s/7w8p6p7shbdhy ... r.WMV?dl=0

The video animation "Disk-Libration" illustrates a schematically a disk libration and the variability of the total Halpha EW that can be expected with it.
https://www.dropbox.com/s/3vgfaaie2drna ... n.mp4?dl=0

The attached Fig. shows the current state of results from collaboration spectra from J. Guarro, E. Bertrand, E. Bryssinck, K. Alich and me. The blue curve represents a fit with a period of 41.5 days and confirms impressively the libration of the disk rotational axis. This is a fantastic result of so far unknown properties of VV Cep.
Ernst Pollmann
VV Cep_EW-Periodicity.png

Ernst Pollmann
 
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Re: New Results of VV Cep

Postby etienne bertrand » Wed Sep 28, 2022 10:22 am

Good works Enrst !

A star perctly for survey in the automn-winter ! Accessible for many astronomers, with C11 : 3x300s with godd snr..
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