Forum der Vereinigung der Sternfreunde

Hi all,

The massive star folks in Montreal are happy to announce that the BRITE nanosatellites will be obtaining continuous, millimag-precision photometry for about 6 months starting in the next few weeks. We would like to suggest an informal campaign to obtain high-quality spectra of two of the most luminous supergiants in the Galaxy simultaneous to the high-precision photometry. The stars are Deneb and P Cygni. I've attached a little write-up of the project below.

Thank you for your help and support!

Noel Richardson

Hello

would radio observations at 21cm be useful?

Regards
Alex

_________________
Everything is Mathematics !

High Noel,

 

I would be proud if I could deliver some echellespectra of these stars in
upcoming summertime. Especially these stars are rather bright. So I should be
able to deliver you some echellespectra between 4750 and 7000 Angström with an R
of about 10.000. An S/N of 200 should be possible.

 

Please tell me if you would accept this and tell me also please where i
should upload these incomming spectra.

 

cheers

 

Berthold

From: fg-spek-convento@vds-astro.de

Sent: Friday, May 23, 2014 5:53 AM

To: fg-spek-admin@vdsastro.de

Subject: [fg spektroskopie] BRITE satellites to monitor
Cygnus

Link
zum neuen Beitrag:
http://spektroskopieforum.vdsastro.de/v ... 163#p25470

Hi
all,

The massive star folks in Montreal are happy to announce that the
BRITE
nanosatellites will be obtaining continuous, millimag-precision

photometry for about 6 months starting in the next few weeks. We would

like to suggest an informal campaign to obtain high-quality spectra of

two of the most luminous supergiants in the Galaxy simultaneous to the

high-precision photometry. The stars are Deneb and P Cygni. I've

attached a little write-up of the project below.

Thank you for your
help and support!

Noel
Richardson

Hi Noel,

Is it OK to cross post this to the ARAS group or do you prefer to keep it within the Convento community ?

Cheers
Robin

Hi all,

In answers to questions raised:

I have no problem with this being cross posted with ARAS.

Unfortunately, 21cm emission will probably not be detected for these stars. The stellar flux at that wavelength is essentially zero for all intents and purposes. A few stars have had their winds measured with radio, but I will have to look into if anything is there for these, but my memory of P Cygni is that the flux is too low at 21 cm.

Lastly, for data transfer, I will get some ftp accounts set up in the next week or two. Then, I can assign them to people. If you are planning on participating, let me know, and we can do data transfer similarly to last year's WR campaign.

Cheers,

Noel

For the guys with a Lhires III and short wavelength range, what are the spectral regions of interest?

_________________
Fil.

Hi Fil,

According to Noel's document

"For observers with an LHIRES spectrograph, we ask that you concentrate on H-­‐alpha for both targets, and then obtain a spectrum of the Si II 6347-­‐6371 lines for Deneb."

Measuring RV of the Si II 6347-­‐6371 lines could be tough though without telluric or IS markers given the (in)stabilty of the LHIRES if the variation is only ~5km/s pp as shown in fig 1. I might try superimposing lamp lines on the actual spectra during the exposure from my Filly lamp mounted at the telescope aperture. The Si II lines are nicely bracketed by strong neon lines.

Cheers
Robin

Document?.. Ahhh!! I missed it (document in the forum and not as attachment on my email), sorry!!
Thank you, Robin, with the added calibration advice!

_________________
Fil.

Hi all,

Please email me if you are observing Deneb and P Cygni. I have ftp accounts at UdeM to drop data into.

Thanks,

Noel

Hello Noel,

I have a lot of older spectra of both stars. If you want them tell me your server connection data by PN or Email.

_________________
Herzliche Grüße / best regards

Lothar

https://lotharschanne.wordpress.com/

Hello Noel,

I have just started monitoring the RV of Deneb using the S II lines. To get the required (+-1km/s?) precision using the LHIRES III I am superimposing calibration lamp lines using a lamp mounted at the edge of the telescope aperture and run during the exposures (see attached example) If these are suitable for you I can upload them.

Cheers
Robin

Hi Robin,

nice, indeed! My english is not so good, to express what ein I want to say respectivly to ask, but I'll try this nevertheless:

I look your image on my IPad ! There I see the spectrum and the calibrationlines. These calibrationlines are not verticaly..I can move the spectrum along these lines and so I cannot get I high precision calibration!?

Ok , ISIS or IRIS they all can (and have to) compensite (?) those tilt angles! Probably this could be the solution of this question!

cheers
Berthold

Hi Berthold,
In IRIS, I use the following commands:

For inspecting:
L_ORI - (select a zone before) this checks the tilt angle of the spectrum, "horizontality"
L_SLANT - (select a zone before) this checks the "slant" angle of the lines (locally), "verticality"

For correcting:
TILT <x0> <angle> - corrects non-horizontal dispersion axis (not needed for Robin's image)
SLANT <y0> <angle> - corrects the angle of the lines at Y value of <y0>

when doing 2D spectra, I use SMILE for un-curving the lines into straight lines. Not needed for stellar spectroscopy

So for Robin's data, it is enough to use SLANT command. <y0> should have the vertical Y position of the spectrum, and <angle> should be the angle that you get from executing L_SLANT on the line you want.

We should not worry about this for the data sent to Noel, though!

_________________
Fil.

Hello Berthold,

The lamp lines are tilted/curved because of the spectrograph geometry. The star spectrum will also move in the X direction the same way if the spectrum is moved up or down. This means that where the lamp lines cross the star spectrum, the wavelengths will always be the same even if the star spectrum is moved up or down.

You reduce them in exactly the same way with geometric corrections etc but you produce 2 spectra, one as normal with the background subtracted (which removes the lamp lines) and one without background subtraction which is used for calibration. (Actually in this case because we are only interested in the wavelength of the star absorption lines and the lamp lines do not interfere with them, we can just reduce the spectrum without background subtraction, calibrate it directly using the lamp emission lines and then measure the wavelength of the S II lines on the same profile. See attached example spectrum profile.)

Cheers
Robin

Note that it is important that the lamp is kept in the same position in front of the telescope and for best accuracy it should be in line with the slit. This is because the line will move slightly with the position of the lamp. See Lothar's study of this for example
http://www.astrospectroscopy.eu/Einstei ... rung_e.htm
Even so there will be small differences in absolute wavelength calibration between observers so an RV standard should also be measured occasionally by each observer to correct for any offsets. (Can you suggest one Noel?)

Cheers
Robin

Attached are initial RV data for Deneb measured at THO. The RV variations in the SiII lines are clear. (4.5km/s range, mean -1km/s to date. The week gap is due to a holiday).
An RV precision better than 1km/s has been achieved using the LHIRES III and simultaneous recording of a calibration lamp mounted at the telescope aperture. The precision is estimated from measurements of Vega as an RV standard.

Does anyone have a reliable absolute RV figure for Vega? The figure of -20.6 km/s given in Simbad does not appear to be correct. My mean is -12.1 km/s, compared with -12.9 km/s measured by me on a spectrum taken from the ELODIE archive and -13.9 +-0.9 km/s from this reference
http://adsabs.harvard.edu/abs/1967IAUS...30...57E

Cheers
Robin

Hi Robin,

I found a RV from alpha cygni at 18.940/06/214 -3.85km/sec using the Si line 6347.1 Angström and -4.36km/sec using Si 6371.36. These values seems to be realisitic to me.

From vega I have no spectra, so I cannot messure the RV from this star. Which line one could use for this on a Vega spectrum?

cheers
berthold

Hi Berthold,

I used the same Si II lines to measure Vega RV (They are not as strong as in Deneb but still very clear) I think it is is good idea to measure a standard star occasionally because there could be small wavelength calibration offsets between different instruments.

Cheers
Robin

Hello Robin,
vega has an extremely fast rotation velocity. This might be the reason why it difficult to get exact values for the radial velocities. May be you should choose a different star for calibration.
http://en.wikipedia.org/wiki/Vega

Cheers
Christian

Hello Robin,

yes, I'll try to get some spectra of vega. Perhaps the Si lines of Vega are not so enlarged caused by high rotation speed like the hydrogen or helium lines. I don't know if it is possible , that such differentes could exist.

Cheers
Berthold

Hello Christian, Berthold,

Yes Vega is a fast rotator but we see it pole on so V sin (i) is very low. The Si II line profiles are very similar in width to those of Deneb so I do not think there is any fundamental problem making the RV measurement. (My results for Vega are very stable over the survey so far, with only 0.5 km/s standard deviation which is excellent for the LHIRES.)

I have now found some more references for Vega RV which agree with the 13.9 km/s figure (and close to my figure of 12.1km/s) so I think the 20.6 km/s reference figure used by SIMBAD is probably in error.

It is important though that we have an agreed RV standard for the Si II line measurements otherwise it will be more difficult to bring the results from different observers to the same baseline. (This is not a problem for H alpha because the telluric lines can be used to check the calibration) I requested an RV standard in a previous post but none was suggested which is why I decided to go ahead using Vega.

Cheers
Robin

Hi Noel,

I am observing deneb and pcygni since june 2014 in every clear night.

cheers berthold

Hi Robin,

I found some spectra of vega from 18.838/06/2014 (JD2456827.3381). And I see the SI lines rather (unexspected!)small and sharp. But I have problems with computing the RV in this case. I found a heliocntric correction of 2.74 km/s for this date.

I found a RV using the 6371.36 of 15.538 km/s; using 6347.1 I found 17.49km/s. But all values are positiv

My mesured differences ( delta lambda!)are for 6347.1 0.37 and for 6371.36 0.33....Could you please find out , what could be wrong here? I thought the RV should be negativ?

cheers berthold

For the same date and time (20140618.9) I get for Vega:

Uncorrected wavelengths 6346.755 6371.025 A
uncorrected delta lambda -0.345 -0.335 A
heliocentric correction 4.5 km/s
corrected RV -11.81 -11.27 km/s
mean RV -11.5 km/s

Observatory location 3.24W 54.75N

Robin

How is the convention? When the values of delta lambda are positive and when there are negative? I computed the HC with Vspec. I am wondering about the differences.....

Cheers Berthold

Hi Robin,

I mesured and calculated once more. Now , now I found the same HC as you......

And I guess that we have a negative RV if the lines are shifted to shorter wavelength. Is it correct?

So I find out at 6347,10 a RV of -12.99km/s at Vega for the 18.838/06/14.

But to determinate the line center with VSPEC ist rather tricky. I realize a big scattering. Perhaps I should use midas to mesure the line center. But this is rather laborious

cheers berthold

(the next time I am here would be the 4.7.14)

Hi all,

It sounds as if people are making some real progress observing and making meaningful measurements. Thank you to everyone. I have some ftp accounts for you to send data to. Please email me (richardson_at_astro_dot_umontreal_dot_ca) and I will give you an account. Thanks again, glad everyone is having good luck thus far.

Clear skies,

Noel

Latest Deneb RV data attached. The quasi-periodic pulsations are clear (currently ~ 12.5 days period ~6 km/s pp).
RV Precision is ~0.5km/s sigma based on measurements of Vega but there is probably a small +1-2 km/s systematic error based on an initial comparison of lamp and solar spectra (to be confirmed).

Robin

Nice Robin, the sky here is always cloudy......

cheers
Berthold

Now 80 days into the observing run on Deneb here at THO. Mean cadence has been just under 2 days (mainly weather related). I am now monitoring H alpha as well as the Si lines for RV.

The run of periodic RV variations has ceased and the trend now appears chaotic. Variations in the H alpha line are subtle but easily detectable day to day (mainly in the blue absorption edge so far)

Repeatedly changing wavelengths on the LHIRES III between Ha and Si has not increased the RV scatter but a ~1.5km/s shift was seen after remounting the calibration lamp (easily detected in the Vega reference checks so can be compensated for)

If measuring the RV from the Si lines, note there are some weak tellurics in this area which should probably be removed for best precision (to be done on a second pass calibration of the THO data). The longer wavelength line of the pair of Si lines also slightly overlaps a weak line on the blue side (at my R ~17000 resolution at least) which probably should be deblended properly before measurement (I have not attempted this yet). I have not identified the line but interestingly it does not appear in the Vega spectrum

Cheers
Robin

edited 31-8-2014 to R value typo

Hi Robin,

Great work! The weak blended absorption line is an Fe II line. It is pretty weak, but we should take it into account during the final measurements.

Thanks, and again, great work!

Noel

[attachment=0]deneb-14-09-09-013i.jpg[/attachment]Noel,

I took 2 spectra of the H alpha line approximately 24 hrs apart which has changed from an absorption line to a P Cygni profile.

Unfortunately I cannot upload the images because I don't understand German perhaps somone can explain how to do this.

I am gathering lots of data for Brite project.

Regards,

Jack

Huggins Spectroscopic Observatory

Trying to get the hang of this.

Jack

Huggins Spectroscopic Observatory

Trying again with second image.

Jack

Huggins Spectroscopic Observatory

Hi Jack,

All my recent Deneb spectra are showing some emission though there is a strong water line in this area at the moment which makes it less obvious. Your second spectrum looks like Deneb but the first spectrum is of a different star (It looks more like Vega)

Cheers
Robin

Hi jack,
            Am in france now till 28th. Have very limited internet due to mobile wifi problems will not be able to respond to emails in a likelihood till i get back.

Good luck with the deneb spectra

john

> To: fg-spek-admin@vdsastro.de
> Subject: [fg spektroskopie] Re: BRITE satellites to monitor Cygnus
> Date: Sun, 14 Sep 2014 13:33:13 +0200
> From: fg-spek-convento@vds-astro.de
>
> Link zum neuen Beitrag: http://spektroskopieforum.vdsastro.de/v ... 163#p25803
>
> Trying again with second image.
>
> Jack
>
> Huggins Spectroscopic Observatory
>

Jack,

Here is my Deneb H alpha for 20140909 (Tellurics removed, heliocentric)

Robin

Hi Robin,

Thanks for the guidance clearly that was the wrong star.

Don't know what went wrong.

I am using a Paramount MX that needs some fine tuning monitoring the H Alpha line as advised by John

Having difficulty with understanding how to upload would like to post a picture avatar is there an English version of tabs available?

Regards,

Jack

Hi Jack! With "tabs" you mean the categories, right? They are bilingual (German | English). The language preferences can be adjusted in the "User Control Panel" which you can find in the upper left corner after login.

Your avatear can be implemented there, as well ("edit avatar").

Cheers, Thomas

Thomas,

Thank you for your help.

Jack

Director Huggins Spectroscopic Observatory

Hi Noel,

there is an impressive collection of Halpha profiles in your project description BRITE_Cygnus.pdf, which is not part of the paper http://iopscience.iop.org/1538-3881/141/4/120/article you mentioned there. It would be interesting to compare these profiles with activities we observed here in the same region in the last weeks.
Is there any related paper to these profiles or a higher resolution image from the same picture available?

Thanks,

Ulrich

found: http://iopscience.iop.org/1538-3881/141 ... 1_1_17.pdf

Regards

Ulrich

These observations of Deneb were made over 2 years ago now. Did anything come of this work? Are there any publications planned?

Thanks
Robin

Hi Robin,

I am also wondering what has happened to all the data of Deneb 1885 spectra I contributed which amounts to many hours of telescope time.

I e mailed Noel last week but no response so far.

Lets hope we hear something positive soon.

Regards,

Jack UK

Hi Jack,
we are a group of austrian and german amateurs who observe Deneb since three years. We intend to continue our program.
Could you give us some information about spectral range and R value of your Deneb spectra?
Regards
Christian

Hi Christian,

I also have a number of Deneb spectra taken in support of the BRITE campaign
2014. (Spectra of Si lines for high precision RV measurement and also some
covering H alpha) If there are no plans to publish the results of this
specific campaign, I will be uploading them to the new BAA spectroscopy
database
https://www.britastro.org/node/8273
and you are welcome to combine them with your data subject to the rules of
the database.

Cheers
Robin

-----Original Message-----
From: Christian Netzel
Sent: Wednesday, November 16, 2016 1:28 PM
To: fg-spek-admin@vdsastro.de
Subject: [fg spektroskopie] Re: BRITE satellites to monitor Cygnus

Link zum neuen Beitrag: http://forum.vdsastro.de/viewtopic.php?t=4163#p28375

Hi Jack,
we are a group of austrian and german amateurs who observe Deneb since
three years. We intend to continue our program.
Could you give us some information about spectral range and R value of
your Deneb spectra?
Regards
Christian


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Hi Robin,
I appreciate your kind offer. However we prefer to leave the door open for a future paper.
Cheers
Christian

Christian,

Spectral range H alpha line.

R around 17000 with a LHIRES III 2400 l / mm grating, C14, Atik 314 mono.

Regards,

Jack

Huggins Spectroscopic Observatory UK