VV Cep: Fe absorptions increase around Ca II doublet

VV Cep 2017-2019 Campaign
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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Ernst Pollmann » Tue Jul 25, 2017 12:50 pm

... 40 km/s differences in RV ?
Could you describe which lines do you used in order to understand it?

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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Peter Somogyi » Tue Jul 25, 2017 3:46 pm

Sorry, forgot to write: that average 40 km/s difference is between my VVCep spectra and an Alp Ori that once I've shot last year (all helioc. corrected).
It should be somewhat expected, looking at simbad vrad difference of both stars. Some errors (+/- 7 km/s) should come from the variable CaII lines, I hope - unable to select regions in ISIS.
But, visually the shift was reasonable, more or less smoothed the continuum.

I will get back with the raw input files and measured data later.

- Peter
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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Peter Somogyi » Tue Jul 25, 2017 7:18 pm

So here is my measurement, using ISIS->Misc->Radial velocity->Compute radial velocity difference, CCF interval: 100km/s, Step: 0.1 km/s, Vh: 0 km/s (for both spectra: one vvcep from the list, and alp ori - already corrected all helocentrically), all in km/sec:

2015.10.05: 49.995,
2016.09.11: 47.955, 2016.09.25: 44.728, 2016.10.04: 43.283, 2016.10.16: 42.499, 2016.10.30: 41.951, 2016.11.27.819: 40.730, 2016.12.03: 44.300, 2017.01.07: 29.046,
2017.05.26: 37.811, 20170604: 40.455 , 2017.07.08: 36.489, 2017.07.16_023 41.235, 2017.07.21: 34.365

and used these values to shift the shrunk Alp Ori negatively. (Maybe I'd use a common average next time, and try other tools selecting the good regions.)

Attaching the input files (incl. Alp Ori - very good by SNR) for local tries to anyone - could be reduced differently: later continuum after 2017.05 was not that nice -, but the generated diagram at this magnification should be fine.

pso_vvcep_uv_20170721.zip
(94.62 KiB) Downloaded 13 times


- Peter
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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Peter Somogyi » Fri Aug 11, 2017 8:33 pm

Result from this week:
state3.jpg


Seems the Fe I depth increased further (linearily by eye - to measure later), whilst the TiII 3900, 3913 mostly unchanged.
Don't draw too far conclusions of these 3 "well chosen" spectra (other than increasing absorptions), chosing other set of spectra have different shortterm variations even on the continuum, but especially on the main features.
Cont. observation 1-2 weekly. Meanwhile started also a serie for the 3700-3860A region as well, however I may shoot that part less frequent.

- Peter
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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Ernst Pollmann » Sat Aug 12, 2017 8:30 am

Hi Peter,
your monitoring within that wavelength section could become from my point of view high interesting. I want come back shortly to my speculation:

"What, if we would assume that the B star does have its own disk, beside the (wind) accretion disk? We would have in that case a superposition of two objects with emission activity. An accretion emission activity (fed by mass flow/wind from the M star) and additionally an emission activity coming from the (fictive) B star disk."

If the companion and its disk is covered, I wonder, whether we have in that wavelength section any chances to find indicators, which enables to distinguish between an "accretion disk" and a "Be star disk".

Steve Shore wrote (2015/08/26):
"The disk will be more like that in a Be system, or any other lower mass accreting pair."

Phil Bennett wrote (2015/08/26):
"The companion is probably quite similar in structure to a Be star, and in fact, one of the closest matches to the ultraviolet spectrum (where only the B star is seen) is Pleione (=28 Tau), a bright Be star in the Pleiades. The main difference is that Be stars are believed to be *shedding* material around the equator due to rapid rotation (because of the large centrifugal force). VV Cep is *accreting* material around its equator".

What´s your opinion?

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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Robin Leadbeater » Sat Aug 12, 2017 2:15 pm

Hi Peter, Ernst

As you know, I am also following this region as suggested by the PI for the AZCas campaign Dr Cezary Galan, Nicolaus Copernicus University, Poland
http://www.threehillsobservatory.co.uk/ ... tra_43.htm

I am not seeing much change in this region yet except for some large and fast variations in the Balmer line profiles which seem larger than at H alpha. (AZCas showed no emission in these Balmer lines.) See attached Hdelta -H10. In particular the event on 20170716 for example. Did anything happen at H alpha on that date ?

Robin

EDITED to correct the Balmer line nomenclature
Attachments
VVCep_H4-H8.png
VVCep_H4-H8.png (228.57 KiB) Viewed 591 times
Last edited by Robin Leadbeater on Sat Aug 12, 2017 6:46 pm, edited 1 time in total.
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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Peter Somogyi » Sat Aug 12, 2017 4:56 pm

Hello Ernst,

The quickly changing UV side Balmer serie (with more and more speed as going inside) suggests it is a normal spiraling material, preferably to the B star.
Also note the H-alpha (almost) vanishing at phi=0.00 (1992 Hack et. al. Fig. 7), so can't imagine that it would come from a disk around an M star - I'm more suspecting the Roche lobe's edge, however also just trying learn here. Of course, other kind of disk (with absorbing material) may be possible, why not.
Comparing the B star to Pleione is an interesting idea, I'll look for the markers (need time to dig up the articles and digest them).

As an example - and to satisfy Robin's questions what happened on 07.16, I've quickly generated this difference graph (sorry for the size, this is what I could generate for now):
table_VVCep_20170708_vs_0715.jpg


These graphs are differences to a somewhat "typical" state (2017.07.08) and a somewhat "exceptional" one (2017.07.15-16 night). I did see such an "exceptional" state on 2016.10.30 as well.
What is easily seen, a huge inverse P-Cyg profile (like a 800 km/s) happening on that exceptional day (both H5 and H6 shows - they confirm each other), whilst H-alpha velocity differences are small (+/- 100 km/s range) and CaII also moderate.
Feel free to download these spectra from the ARAS database, just got refreshed yesterday.

- Peter

PS.: A typo on the graph title is the accurate date, that H-alpha was created right before or after the UV part... not going to fix this, see the database for my nearby H-alpha material, always shooting with the same session.
PS#2: Echelle owners should come up with their analysis on H-beta ... H-delta
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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Christian Buil » Sun Aug 13, 2017 12:01 am

A VV Cep H&K spectrum taken during OHP spectro party (27 / 07 / 2017) (Lhires 1800 g/mm on C8 telescope) :

Image

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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Ernst Pollmann » Sun Aug 13, 2017 10:23 am

Hi Robin & Peter,
to my surprise, the Vmag-corrected Halpha flux shows within of a comparable time window a cyclic variability with a minimum approx. to that time, which Robin emphasized (JD 2457953). See the following Fig.
halpha-flux.png
halpha-flux.png (13.56 KiB) Viewed 543 times

Robin & Peter:
I would recommend to extend your analysis once more corresponding to the time window I am showing here.

Once more: accretion disk plus Be star disk?
When we analyze the higher Balmer lines the question is, where they have been formed? In a (fictive) Be star Kepler-disk, or in a B star accretion disk? Or both?
The velocity variations in Robin´s plots might point out to turbulences in the optic deeper zones. If we would assume, Kepler rotation within the disk(s), then we could expect variations in velocity (cyclic ?).
As Steve Shore wrote correctly:
The (emission) line formation depends on local effects and those can arise for a wide range of causes.

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Re: VV Cep: Fe absorptions increase around Ca II doublet

Postby Peter Somogyi » Sun Aug 13, 2017 6:11 pm

Ernst,

Now I understand which 2 disks are you referring to.
Please give me some time (already playing around), basically the red part of H6 (= big absorption) show any correlation, but I doubt an absorption was connected to Halpha, and too few checkpoints I have there yet (only 6).
Currently what I'm stumbled into, that Fe line really needs removal (= it's after reducing Alp Ori by usual 1/6 multiplier - continuum much better after that):

vvcep_alpori_reduced_20170807.jpg


Maybe I'll just manually fix that line at 3886.2A... nicer would be a tool (sth. like ISIS/H2O removal but with these Fe lines), pls let me know anybody if aware of such.
Cont. efforts later.

- Peter
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