VV Cep: Fe absorptions increase around Ca II doublet

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

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

Postby Peter Somogyi » Sun Mar 10, 2019 2:50 pm

Dear All,

I've been following this object in eclipse from 2018.05.26 - 2018.12.31.
However, it's been rather eventless during eclipse, and I won't be able to observe it again till end of 2019 MAY.
Despite little (real) changes, presenting here last year's result:
This graph includes results also from 2017 (first 3 blue dots)
vvcep_uv1_20180108_20180804.png (100.1 KiB) Viewed 1687 times

vvcep_uv1_20180909_20181231.png (101.43 KiB) Viewed 1687 times

vvcep_uv2_20180701_20181030.png (122.02 KiB) Viewed 1687 times

I've also started measuring flux using my photometric slit's wide part:
vvcep_fluxes_2018.png (13.53 KiB) Viewed 1687 times

Blue dots fluxes + the very first green dot flux measurements are estimated by earlier method (viewtopic.php?f=19&t=1798&start=80#p10027).
Took typically ~ 2 minute for ref. star, 2 minute for 7 Cep (as a 2nd check), and 10 min. for VV Cep itself. Then usually taken 12 x 600 for the higher UV region, and 6 x 1200 seconds for the lower UV region.
When switcing to wide slit (= the first red dot on graph), started using the ref. star 27 cyg from Miles, but since 2458370 (2018.SEP) switched to 11 Cep.

Only spotted one remarkable event, on 2018.12.31 the H8 feature seems to have changed (but no further data). This is in sync with Alpy observer's H-beta changes.
The bad weather in Nov-Dec prevented me any observation, and afterwards I was not lucky enough to catch early evening with any clear sky. Next possible observation could be the end of May.


EDIT: uploaded these spectra (taken in 2018) to britastro specdb.
Peter Somogyi
Posts: 414
Joined: Sun Jul 13, 2014 8:56 am

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

Postby Peter Somogyi » Sun Jun 28, 2020 9:12 am


Finally, got enough time to process my VV Cep obsertvations about the egress phase, continuing with flux (same way as in 2018 during eclipse).
Followed only the CaII region (3850-4005A) for the egress at R~5000 (except 20191229.751 that is showing deep reverse P-Cyg, such as before ingress), using same instruments (300/1200 Newton + APM Barlow 2.67x + LHires III + 2400/mm grating + 35 micron slit + ATIK 428 EXm + external UV flat).

Firstly, I have missed most of the chromospheric egress, got only 1 spectrum (2019.03.23: JD=2458565) resembling as an intermediate state:
egress1.png (150.27 KiB) Viewed 865 times

However, within 1 week on 2019.05.18 - 05.24 (JD: 2458621-2458628), there has been a sudden jump in the continuum flux, accompanied with strong CaII emissions appearance:
egress2.png (136.77 KiB) Viewed 865 times

It is easy to prove, that both the CaII doublets (3933, 3968 A) got suddenly the strong emissions (e.g. subtraction of previous spectrum).
Further away from eclipse, a similar flux level of continuum sustained and slightly increased, with later the reverse P-Cyg appearing on both CaII and Balmer:
egress3.png (127.32 KiB) Viewed 865 times

The strong CaII emissions remained on ALL spectra since JD:2458628, and it was not present before (back in eclipse).

The appearance of CaII emission (JD: 2458621-2458628) is somewhat symmetric by timing with the disappearance before ingress (it happened few months before ingress).
Earlier literature's public data does not have such a dense time serie about this emission, and the coincidence with sudden flux increase may be not random.

Uploaded spectra to britastro.org/specdb .
Finishing this project for now, plan to take maybe 1 per year in this region.

Peter Somogyi
Posts: 414
Joined: Sun Jul 13, 2014 8:56 am

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

Postby Ernst Pollmann » Sun Jun 28, 2020 5:13 pm

Hi Peter,
as you know our professional tutor Phil Bennett is writing in collaboration with his phd student and us a further more scientifically paper. The results of your observation within this spectral range might be worth to account. At present I am going to collect all the spectra I got during the last three years to offer it Phil, for a new and more extended (than I did it) evaluation by his student.
Ernst Pollmann
Ernst Pollmann
Posts: 391
Joined: Mon Sep 26, 2011 7:16 pm


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