V Sge

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Peter Somogyi
Posts: 420
Joined: Sun Jul 13, 2014 8:56 am

Re: V Sge

Post by Peter Somogyi »

Fresh result from this Friday evening, on top of this compilation:
vsge_all3_compr9.png
Blue part have the same exposures, H-alpha was scaled fully differently.
As for tellurics, would be nice to know a standard method to follow here (2 methods I'm aware: one is to have a ref.star - tried but result is contaminated by noise and H-alpha middle, other is synthethic reproduction - haven't tried yet). Sending uncalibrated (left part of H-alpha on 20160723.839 affected the most).

- Peter
Francois Teyssier
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Location: Rouen
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Re: V Sge

Post by Francois Teyssier »

All that is very good
Should be interesting to link the observations to phase

I found :

Ephemeris for the primary minimum by
Mader & Shafter (1997): T(min) = 2,437,889.913(5) + 0.514195(4) x E

François
Peter Somogyi
Posts: 420
Joined: Sun Jul 13, 2014 8:56 am

Re: V Sge

Post by Peter Somogyi »

Thank you Francois for the formula and author names (allowed to google for article), now I've been able to create that chart:
vsge_phase_compr.png
Continuum supposed to be at 1, but scaled to 0.05 for H-alpha, 0.12 for H-beta and 0.07 for HeII 4686 on the above graphs (and continuum is added to the phase in the interval of [0..1]).
Applied shift as the absolute period.

Using all of my spectra (including a very noisy one available at blue only) + used Francois's observation on 07.14 (asdb_vsge_20160714_036), rectified continuum on it in both blue and red separately, and did a gauss filter 5 on it so now matches well by both SNR and resolution. (Unfortunately, I was able to download only this spectrum for extending my serie.)

I think the formula works well (couldn't go to sleep without trying...), was fitting the graph sizes to this:

http://iopscience.iop.org/article/10.10 ... /fulltext/
http://iopscience.iop.org/article/10.10 ... 6.fg1.html

We are somewhat different I think, but the period still seem to apply.
More spectra should be welcome I think, especially from the missing middle phases... (might require a proper scheduling)

Cheers,
Peter
Francois Teyssier
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Location: Rouen
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Re: V Sge

Post by Francois Teyssier »

Very nice !
I updated the database with Tim's spectra

François
Peter Somogyi
Posts: 420
Joined: Sun Jul 13, 2014 8:56 am

Re: V Sge

Post by Peter Somogyi »

Including now Tim's spectra (0724.004, 0727.024), revealing the middle phase:
vsge_all_compr.png
This time made a local continuum fit around H-alpha, too.
Did set the continuum to 0-level this time, considering the skew is misleading.
I can reproduce the above diagrams in postscript when necessary (fully batched via IRAF now).
As before, was using JD-MID (without any HJD conversion - could introduce just 8.3 minute skew).

I think the color composite of the above should also be interesting:
vsge_all_composite_compr.png
vsge_all_composite_compr.png (11.89 KiB) Viewed 10189 times
Look at the differences of HeII 4686 and H-alpha on top and bottom (should be real, I think).

- Peter

Notes:
- fixed my own asdb_vsge_20160730_011.fit JD-MID locally, forgot to handle when applied per-exposure calibration manually (visible as JD-OBS being too close to JD-MID)
- colors yet need more manual effort, can't plot colors in .ps via IRAF somehow
- used 4686, 4861.33, 6562.7 A for the zero references of velocity (couldn't find more accurate wavelength for He II 4686), maybe the He II could be tuned further
- I can publish IRAF the commands on another forum when someone is interested

EDIT: looking at differences on the color diagram H-alpha being too far from other features (also in time), but the eShel one matching all 3 features on 07.14 too well, puts up a suspect here some assumption being wrong. This needs more investigation.
Paolo Berardi
Posts: 578
Joined: Thu Sep 29, 2011 10:51 pm

Re: V Sge

Post by Paolo Berardi »

Hi all, two observations coordinated with Umberto Sollecchia. I took V photometry (Mak90, SXV-H9, Baader V filter) and mid-res spectroscopy (Lhires III 1200). Umberto took low-res spectrum with Alpy 600. We started about at the same time in order to have simultaneous data.

Photometric data:

Mak 90
V Baader filter
SXV-H9 CCD camera
Astroart 6 software
ApassV magnitude of field stars

Spectrophotometric method uses:

V filter specific transmission curve
Mean zero point calculated with some CALSPEC profiles convolved with V filter curve
Mean V magnitude during the spectra integration

The V mag curve on 3 august night (I think we observed during one of the brightness maxima):

Image

Low-res profile:

Image

Mid-res profile in the h-alpha region:

Image

H-alpha line heliocentric radial velocity:

Image



A previous attempt made on 30 july (not exactly synchronized), when the star brightness was decreasing.

V mag curve:

Image

Low-res profile animation with V photometry (five profiles composed of 4 x 360s subexp.)

Image

Mid-res profile in the h-alpha region:

Image

H-alpha line heliocentric radial velocity:

Image

I wonder if the spectrophotometric method used is a better choice with so quickly variable targets, compared to using direct methods such as large slit observations. Any suggestion in this regard is welcome.

Paolo
Peter Somogyi
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Re: V Sge

Post by Peter Somogyi »

Paolo, Umberto, it's very nice, I'm also having some more spectra on this in my queue. I'd recommend sending all in a form of serie, as I can see at least the HeII 4686 looks having features shifting every 20 minute!

Cheers,
Peter
Joan Guarro Flo
Posts: 611
Joined: Thu Nov 03, 2011 8:50 pm

Re: V Sge

Post by Joan Guarro Flo »

Paolo & Umberto:

You made a good team.
The result is eloquent, is very nice, congratulations !!

Un forte abbraccio, Joan.
Paolo Berardi
Posts: 578
Joined: Thu Sep 29, 2011 10:51 pm

Re: V Sge

Post by Paolo Berardi »

Peter, Joan, thank you for your comments! The target is very interesting and deserves a frequent monitoring. Following the single profiles animation.

Low-res (360s resolution):

Image


Mid-res (960s resolution, some changes in the blue side of the line):

Image

We do need larger telescope apertures...

Paolo
umberto sollecchia
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Re: V Sge

Post by umberto sollecchia »

Peter, Joan, je vous remercie beaucoup d'avoir partagé notre travail.
Salutations
Umberto
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