VV Cep: Fe absorptions increase around Ca II doublet

[Peter Somogyi]

Robin, I've observed the Ca II doublet on 08.18 but nothing much changed compared to 08.13.

On the other hand, I've started to shoot a region 3705-3860A (can concatenate with my already published 3850-4000A) and want to follow it till I can, despite the bad SNR (half in the middle, 1/4 at left end than the CaII region). Got roughly R~3000, and calibration is more troubled (RMS around 0.010 A error, using order=4 polynom - on the contrary, 3850-4000A region has no trouble at all). But, I still consider it to be useful for the overall line identifications - especially with following the absorption changes:

vvcep_20170715_0818_muCep_sub_PSO.png (18.25 KiB) Viewed 4660 times

In the last spectra, favouring 4 x 20 minute or even more as told it's much harder.
Mu Cep was good to remove (in this picture), though may need to rework as on the last 2 spectra it seems to be less perfect.
I'm unable to identify many of the lines, some may be FeI but seeing much more. At least, the H8 at 3797 (in the middle) seems to be more or less intact, disturbed only by 1-2 absorption lines.
Sending them to database soon.

- Peter

[Robin Leadbeater]

Hi Peter,

Unfortunately I will no longer be posting on this subject here. This is disappointing to me as the ARAS forum has traditionally always been a completely open forum.

Rgds
Robin

[Peter Somogyi]

Robin, I'm sorry for your departure on this topic here, and hope you may return soon.
However - without consulting any Admin people or agreeing before -, my view on the new rule that it's not unreasonable and used at many other places, but such a discussion must be continued on a moderator forum topic.
- Peter

[Robin Leadbeater]

Hi Peter,

Do not worry. I have not left the ARAS forum. Monitoring the blue end of the spectrum was never part of Ernst's VV Cep H alpha campaign so I will post future results in the currently unmoderated "Spectra, results, information on activity ..." section of the forum

Cheers
Robin

[Peter Somogyi]

Robin, of course, if you feel more comfortable with usual method - especially if can attract further observers -, I am ready to join.
But don't feel on this forum unwelcome, SAS_2015.pdf (and further forum comments) explicitly encouraging this area (<4000A), we just need to lie on ourselves when presenting material to prof. contact since nobody else than us have observational practice in this region so anyone else will hardly trust or interested in what we do. Hence need higher theory learning + presentation effort to get us noticed and get the proper feedback early enough (have the changes understood and whether interesting enough).

Words enough, here is the latest CaII state, central spike gets separated, and deeper absorptions seem to be permanent:

vvcep_ 20170527_031_PSO_sub.png (86.24 KiB) Viewed 4555 times

BTW. I would appreciate to get +1 observer who does similar resolution + SNR what I do, for continuity and confirm reason.

- Peter

[Ernst Pollmann]

Hi Peter,
this is a really great time series of one of the typical atmospheric eclipse effects.
I hope that Phil Bennett comments these measurements and also the Halpha results soon. There are some open questions.

Ernst

[Peter Somogyi]

Ernst, I will come up with an EW graph soon (weekend?) as soon as I rework the Alp Ori subtraction better (ratio determination suggestion welcome - rather than my lazy constant 1/6) and find the more reliable continuum parts around a given feature. As you see at beginning this topic, already detected metallic lines at end of May. Maybe it matches with the H-alpha timings, however since it's not a discrete cut - rather than very slow (sometimes non-monotonic) changes, it is yet very hard to speculate, and yet some other aspects I want to extract from my data (CaII and H6 also decaying slowly with time, with high shortterm variations)...
Also want to detect from EW graph what's the gradient of the curve of a feature like Fe I (FeI incerase seems so far looks linear, but the Ti II 3913 elongated), that's why trying to shoot at a higher cadence (and request +1 observer).
So far my question is whether I should enforce the 3700-3860A region, or should I focus to 3860-4000A instead and do more exposures here (will have to, in 2-3 month of time).
Also planning to shoot at high resolution of CaII when have a 2nd consecutive night, getting it from any other observer with a smaller scope could also be done (slit width less affecting for smaller scopes) just to resolve and identify lines once.

A quick note about my 3700-3860A serie: I'm reworking the wavelength calibration, detected a larger error (few A) towards the 3700A, and will update that serie of spectra within a few days. Sorry for the mistake, it's the 1st time I'm extracting data in this region.

My specific questions to Phil: how the professional (HST ?) observations ongoing nowadays (what cadence)? Can my observations be matched with earlier eclipse HST data (assuming there was an overlapping region usable) to determine the exact period we are at currently? Are those spectra downloadable by amateur? What is its resolution and SNR, is there an overlap?

- Peter

[Ernst Pollmann]

Ernst, I will come up with an EW graph soon (weekend?) as soon as I rework the Alp Ori subtraction better (ratio determination suggestion welcome - rather than my lazy constant 1/6) and find the more reliable continuum parts around a given feature. As you see at beginning this topic, already detected metallic lines at end of May. Maybe it matches with the H-alpha timings, however since it's not a discrete cut - rather than very slow (sometimes non-monotonic) changes, it is yet very hard to speculate, and yet some other aspects I want to extract from my data (CaII and H6 also decaying slowly with time, with high shortterm variations)...
Also want to detect from EW graph what's the gradient of the curve of a feature like Fe I (FeI incerase seems so far looks linear, but the Ti II 3913 elongated), that's why trying to shoot at a higher cadence (and request +1 observer).

Peter, may be after your drawing the EW time behaviour of that lines, the accordance of disk eclipsing time will be more clear. It would be interesting to see that result. Obviously it is hard to create enthusiasm for this wavelenght area.

So far my question is whether I should enforce the 3700-3860A region, or should I focus to 3860-4000A instead and do more exposures here (will have to, in 2-3 month of time).

It´s hard to decide this. If your capabilities does allow, you should try both.

A quick note about my 3700-3860A serie: I'm reworking the wavelength calibration, detected a larger error (few A) towards the 3700A, and will update that serie of spectra within a few days. Sorry for the mistake, it's the 1st time I'm extracting data in this region.

No reason to excuse, more important is the detection of errors.

My specific questions to Phil: how the professional (HST ?) observations ongoing nowadays (what cadence)? Can my observations be matched with earlier eclipse HST data (assuming there was an overlapping region usable) to determine the exact period we are at currently? Are those spectra downloadable by amateur? What is its resolution and SNR, is there an overlap?

Hope that he will reply soon, today I wrote a reminder.
Ernst

[Peter Somogyi]

Hello,

Rainy season allowed to rework my faulty calibration of the 3700-3860A covered spectra (besides processing new ones), now using the normal order=2, updated in the database by now.
As for the longterm follow of the H6+CaII (3850-4000A) region, found a method to subtract Alp Ori in a more reliable way, using the continuum slope as a property (peak at 4000A difference to a chosen continuum, more details on demand). Let me note that mu. Cep won't work, there are big differences at this resolution to Alp Ori.
This is reduction is necessary to speak about continuum in this region, allowing to provide EWs.
Here is what I could extract, using IRAF/splot/d (deblend) method, gaussian fit for a few selected absorptions (more features later):

vvcep_state_2016_20170909.png (10.52 KiB) Viewed 4354 times

and results since end of May:

vvcep_state_20170526_20170909.png (10.08 KiB) Viewed 4354 times

The Fe I 3878 is the easiest to determine, it has reliable continuum around, visually can confirm its appearance is really starting from the end of May.
The 3872 (Fe ?) is coming up later only (2017.07.21 = JD: 2457956 visually to appear).
The Ti II 3900A is blended by Fe line, can use only 3913A - however, continuum is harder to determine here, I'd expect its EW was 0.2 all the last year. And, is definitely detached from the Fe I feature.
Last observation done on 09.09 (and 09.08 - took an experiment to see what changes in 1 day; seems H6 - and H5 - are a bit), having cloudy/rainy forecast since then.

- Peter

[Peter Somogyi]

Dear Audience,

Due to the bad weather in the past 2 weeks, I must have missed a bigger event of the eclipse:

Question whether if accidentally something else has hid the B component - not the M core -, but now VV Cep got resembling more to the Alp Ori, roughly by 70-80% visually (precise calculations to come later):

(The RV shift in between is expected, both spectra only helocentric corrected.)
Still left some time till the totaal eclipse, but unsure how much.

Cheers,
Peter