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 Post subject: wr140-first lights
PostPosted: 29. October 2007, 20:12:31 PM 
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Nutzer

Joined: 29. October 2007, 12:10:27 PM
Posts: 12
Greetings all,

Last Friday I managed 2 spectra of WR140, one with 300l/mm (attached) and another with 1200l/mm not yet processed. I used a C9.25, a SBIG ST10XME, and a Lhires3 with a slit openning of ~40 micron and 40 min exposure. I used Castor for determinig the instrumental response, but as I've never worked on these spectral domains, I'm in doubt about the results, because I was expecting an outcome with lower reds in the continuum. I must say that when I collected this low-res spectrum, the star was very low ~15º above horizon.
Some comments are wellcome, because I need to put in order my setup and procedures for this campaign. I'll post here when I have wr140 (==>) 1200 l/mm processed.

Best regards
Jose Ribeiro


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 Post subject:
PostPosted: 29. October 2007, 20:29:31 PM 
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Joined: 01. August 2006, 16:08:56 PM
Posts: 3823
Location: 68163 Mannheim
Hello Jose,

thats fine that you contact us !!!!

How did you the calibration of your spectra ? By neonlines?

best greetings
Lothar


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 Post subject: wr140-first lights
PostPosted: 29. October 2007, 20:55:41 PM 
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Nutzer

Joined: 29. October 2007, 12:10:27 PM
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Greetings Lothar,

I calibrated this low res spectrum with the Neon lines in first approximation and then recalibrate with some Neon lines + Na lines and Hbeta line (wright/ wrong proccedure?) using VSpec.

best regards
Jose


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PostPosted: 30. October 2007, 09:46:02 AM 
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Joined: 31. July 2006, 16:43:32 PM
Posts: 3434
Location: Köln
Hi Jose! Welcome aboard! :D Finally we got our first international colleague...that's great!

Your results are phantastic.
Quote:
I was expecting an outcome with lower reds in the continuum.
Please keep in mind that you are not observing a real continuum. The star has a completely optical dense environment in form of a radial symmetric wind in all atomic species. You can not see the stellar photosphere and WRs are not classified in the HR domain. What you see in the "continiuum" is just light from electron scattering within the wind.

What are the "corrected" and "uncorrected" spectra?
Quote:
I'll post here when I have wr140 (==>) 1200 l/mm processed.
Yes, that is the probably most convenient setup. As you can see in our WR 140 web site. Berthold Stober was very successfull with LHIRES plus 1200 Grating. We are eager to see your output!!!

Just today I obtained the following message from Tony Moffat at Université de Montréal (I will place it into the WR site, too). He explicitely asks for spectra in all wavelengths beginning now once every month (more would be even better) and more often later:
Code:
Hi Thomas:
 
Two weeks ago I was in Madrid (well ESA/Vilspa actually) for a 3-day meeting with 6 others on WR140 - just WR140!  Everyone could give a talk for 3 hours - great stuff.  With lots of interaction and no such thing as dumb questions.  But no time to stop off in Germany this trip.
 
During our discussions of all aspects of WR140 from radio through IR, optical, UV, X and gamma, one aspect which really came up often was getting the right orbit, based on both sets of lines (WR and O).  For that we'll need good time coverage and good quality optical spectra.  So the role of your amateyr friends could be quite crucial and we support their efforts.  Ideally, we need steady coverage in time (once a month now), then by October 2008, increased to once every couple of nights and every night in Dec/Jan.  Yellow spectra are good, but also blue would be useful, to get more O-absorption lines for a good orbit of the O star.  S/N should be at least 150/pixel and no worse than ~1 A/pixel, if possible (to get good precision in RVs).
 
We should also get broadband (UBV best) photometry, around and after periastron passage, to look again for dust-caused dips, from which one can compare with dust models to constrain dust-grain size.  Any chance of that, too?
 
Ciao,  Tony
I consider this request as a serious starting signal which includes carefull and exact data reduction. We are now working with the pro's!!!

Greetings from Bonn, Thomas

As soon as we have an anglophone participant I ask everybody to switch to english within the respective discussion. - Sobald wir einen anglophonen Diskussionsteilnehmer haben, bitte ich alle um Beiträge in englisch innerhalb der entsprechenden Diskussion.


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 Post subject: wr140-first lights
PostPosted: 30. October 2007, 21:53:04 PM 
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Nutzer

Joined: 29. October 2007, 12:10:27 PM
Posts: 12
Hello all,

Thank you for your kind words!
About the question of Thomas, "corrected" of intrumental response.
In append the spectrum taken with the 1200l/mm grating, in jpg and fits (BeSS protocol). Once more, sorry if there are some errors detected, I need to improve my procedures. One issue in frequency calibration, is the fact that I'm using the Neon, and the bluest line is in the middle of the spectral domain. This induces for sure a calibration error to the blue part of the spectrum, when applying the polinomial fit!! How can I overcome this problem (without having to by an expensive calibration lamp)?

Thanks
Best Regards
Jose


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 Post subject:
PostPosted: 31. October 2007, 13:59:00 PM 
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Joined: 31. July 2006, 16:43:32 PM
Posts: 3434
Location: Köln
Hi José!

Yes, that looks very nice. Good work! The reason for starting relatively early before periastron passege is to improve the procedure and due to Tony Moffat getting as much spectra as possible even in this early phase. So you are in a perfect loop!

The instrumental response will not be considered after rectification of the "continuum" (I keep this nomenclatura although it is not a real continuum). The intervals to rectifiy correctly can be found in the paper of Marchenko et al. (see Literature within the Wr140 page).

The calibration problem should be solved as good as possible. Tony pointed on the problem of orbit estimation!!! If you LHIRES guys do not trust in the Neon calibration...well, then you should think about another lamp. But proper wavelength calibration ist essential here. Sorry for this answer, but I have no better idea.

In addition, you need to improve S/N. Berthold exposes about 2 hours to get S/N ~ 150.

Cheers Thomas


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 Post subject:
PostPosted: 31. October 2007, 20:58:49 PM 
Hi Jose,
in your mail contact as of Oct 29th you wrote that you've used a 40 micron slit. Could you please give me an idea about your avarage seeing conditions (arcsec)?
Regards,
Norbert
www.keyhole-online.org


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