|Forum der Vereinigung der Sternfreunde
|Message from Sergey Marchenko
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|Autor:||Robin Leadbeater [ 01. Juni 2008, 14:02:29 PM ]|
|Betreff des Beitrags:||Message from Sergey Marchenko|
I contacted Sergey as Thomas suggested and he has kindly given us more details of the rectification process he used and also a file of the mean spectrum published in his 2003 paper (I have converted it to fits format and attached it as a zip file.) His full message is below
---- Original Message ----
From: Sergey Marchenko
To: Robin Leadbeater
Sent: Sunday, June 01, 2008 12:03 AM
Subject: Re: WR140 Periastron 2009
> Hi Robin,
> first of all, my apologies for a late reply. I'm no longer employed
> as a professional astronomer, and my new lob is
> fairly demanding, for the moment. I went over my 10+ years-old files
> and found something which might help
> you: a mean low-resolution spectrum of WR 140 ( I believe the same
> you use as a reference) . I attach it below
> as a simple text file, rectified flux vs wavelength.
> The slight mis-match (yours against the template) in the overall
> strength of the emission line could be caused either
> (a) the difference in the adopted continuum rectification procedures
> (b) a secular variability of the WR wind.
> The latter can be checked by comparing the strengths of the emission
> features adjacent to CIII. If you see (assuming that
> your spectral coverage allows it) systematically stronger emissions
> across your spectrum, then this has nothing to
> do with the adopted rectification (continuum fitting) procedure. One
> would always expect <~5% long-term trends in
> WR winds.
> However, I suspect that the item (a) could be blamed too. Please
> ckeck the attached file and see the regions where
> the rectified flux comes close to 1. These (la~5368+/-2 A, 5534,
> 5754, ~5967) where used for rectification. As far as
> I remember, I usually went for a quadratic or a cubic polynomial.
> One more issue: please be very careful with the wavelength
> calibration. What I mean is that, ultimately, all the available
> spectra should be brought to a helio-centric frame of reference.
> I.e., all the variations caused by the orbital motion and rotation of
> Earth should be taken away. This was done in the attached template.
> I'm saying all this because I noticed a slight shift in the IS
> Hope this helps! Please let me know if you have any further questions.
|Autor:||Lothar Schanne [ 01. Juni 2008, 14:57:02 PM ]|
|Betreff des Beitrags:|
I've plotted the spectrum in the annex. For better "seeing" klick on the graph.
|Autor:||Robin Leadbeater [ 01. Juni 2008, 19:40:36 PM ]|
|Betreff des Beitrags:|
It looks like there are some bad values at the edges of Sergey's plot but I can now make a more accurate comparison with my Dec07-May08 average. (attached) Very close
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