V1687 Cyg

[Francisco Campos]

Hello,

a few days ago the AAVSO launched an observational alert about the eclipsing V1687 Cyg. Looks like it is a good opportunity to be enroled in a Pro-Am project where high-resolution photometry is requested but also good spectroscopy with at least R=5000 (I don't know if they will accept low-resolution spectroscopy).

The star is bright and to do photometry a small short-focal 60mm refractor would be enough, but I think that a good photometric CCD camera (type KAF 1603ME, for example) is mandatory. For spectroscopy it seems a good target for small-medium scopes (8").

I am seriously considering to enrol in this project, it seems exciting and a resolution of 5000 it's possible to my DADOS spectrograph and a grating of 1200 l/mm. Meanwhile, I will take a low-resolution spectra in order to know a bit more this binary star (WC+O-type stars).

Here is a link with more info.

https://www.aavso.org/sites/default/fil ... ct2016.pdf

Greetings
Fran

[Olivier Thizy]

Francisco,


thank you for the information, this seems a ery interesting project but challenging as Cygnus will be low at that time of the year; I also have trees & city light pollution in that direction in the evening and mountains/trees in the morning so I do not think I'll be able to follow up after periastron but I can try.

Here is one single 900s exposure I took tonight; sky very cloudy so I couldn't do more and signal/noise is very poor. I use a C11 (0.28m) telescope and echelle (R=10000) spectrograph. Despite low signal/noise I can see the CIV line with some features in the middle:

Here is the full spectrum but I should be able to get better profile under better sky conditions:

I also include the FITS files (one for the merged spectrum and an archive with indidual echelle orders):

Results.zip

(442.54 KiB) Downloaded 414 times

Cordialement,
Olivier Thizy

[Olivier Thizy]

Hello,


I had better skies tonight and was able to take a 40min (4x10min) exposure on WR140 with the 11 inch telescope and echelle spectrograph. Result is a better signal/noise ratio and a nice overall spectrum:

If there is some interest, here is the spectrum (merged & individual orders):

Results.zip

(434.29 KiB) Downloaded 419 times

Cordialement,
Olivier Thizy

[Peter Somogyi]

> Results.zip

Thank you Olivier for sharing this, I must confess I gave a lot of try over the past 2 weekends for high resolution of WR140 to analyse the ripples I have between 5750A-5900A with the 414 EXm (+ LHires + 2400/mm + 35um). No luck yet, even with trying the hot star method - somehow the ripples I see dependent of the actual shape of the feature, and quite reproducible and not a flat skew. Hope once I can come up with a method.

Cheers,
Peter

[Olivier GARDE]

Here's my contribution taken last night with eshel spectrograph R=11000.

[Robin Leadbeater]

Hi all,

More on this here.
http://spektroskopieforum.vdsastro.de/v ... =32&t=4451

It is a follow up by the Convento Pro-Am group to compare with the results from the campaign run last periastron. This is what I saw then
http://www.threehillsobservatory.co.uk/ ... tra_41.htm

Cheers
Robin

[Robin Leadbeater]

And also already announced on here some weeks ago of course
http://www.spectro-aras.com/forum/viewt ... =20&t=1483

Robin

[HughAllen]

I am interested to know whether the changes in the CIII emission around periastron may be visible at the resolution of the Alpy 600. I looked at your report on your website Robin, on the last periastron in 2009, and the scale of the changes in your excellent animation look to me like they should be resolved. What do you think? I am in any case taking baseline spectra on the assumption that the results will be positive as December approaches I attach a baseline that I captured back in July, using the Miles database star SAO68678 for calibration
Cheers
Hugh

[Robin Leadbeater]

Hi Hugh,

Yes I would say the change on the top of the line as the winds collide would easily be visible at ALPY resolution,though higher resolution would needed to pick up the precise nature of the changes and the moving clumps in the wind. Based on what I saw last time, I recommend keeping the SNR as high as possible, making sure your zero level is good (ie good dark and background subtraction) and rectifying the spectrum using a low order spline fit to the pseudo-continuum using the points that Marchenko used. See fig 5 of this paper
http://adsabs.harvard.edu/abs/2003ApJ...596.1295M

Cheers
Robin

[Francisco Campos]

Hi,

talking about comparison stars, do you think it is a good idea to choose a unique comparison star, in order to minimize possible systematic errors? Well, because I don't have still experience in high-resolution spectroscopy, maybe it is not necessary to be so stricty on this point, But in photometry I believe that it is highly recommended.

Here is a low-resolution spectrum taken with the DADOS and HIP 100518 (B8 V) as comparison star.

_v1687cyg_20160823_844.png (8.18 KiB) Viewed 8524 times

Greetings
Fran