Beta Monocerotis

[James Ley]

Here are some spectra I took of the three components of the Beta-Monocerotis system. They are all Be stars with emission! A is separated from BC by 7.4” and B and C are separated by 2.8”.
Here is the spectrum for A

Beta Mon A.png (15.91 KiB) Viewed 6441 times

When I took these spectra B and C were together on the slit of my ALPY 600 spectrometer, but I was able to see their two spectra.
The system looked like this.

Beta Mon.jpg (1.96 KiB) Viewed 6441 times

and the two spectra of B and C looked like this

Here is the spectrum of B.

Beta Mon B.png (13.75 KiB) Viewed 6441 times

Here is the spectrum of C.

Beta Mon C.png (15.81 KiB) Viewed 6441 times

Is there a way to easily rotate the orientation of the ALPY slit without losing focus and/or having to recalibrate the tracking?
I read on Chrisian Buil’s website where he mentions a 9 um slit for the ALPY. Does anyone have experience with smaller slits for the ALPY?
I DID NOT process these spectra with ISIS (because I didn't know how to separate B and C).
Thank you.

[etienne bertrand]

Hello James,
Your CMOS camera for the aquisition spectre is ASI 178MM (cooled) ?
It's possible to have the orignal spectra for work it ? (dark, offset, flat, star and calibration) ? I'm interessted by this cmos results .
I don't know if there is interference wave in the continuum (540nm to 660nm) ? How many spectr you take for a star ? because it's possible there is noise in the spectra.
Maybe the instrumental response will be better because your spectr right.
But it's good spectr !

[James Ley]

Hello Etienne,
Oops I made some mistakes and you noticed.
Because I wasn't sure how to separate the spectra of B and C with ISIS, I used RSpec. The spectrum of Beta Mon A is from one 80 s capture and the spectrum of B and C is from one 160 s capture. I made around 10 images of each. I also captured Zeta Leporis as a reference plus flats, darks and a reference, but I have never processed these. I would be very happy to share my data if you could tell me how.

Now that I think of it, I have few spectra I have processed with ISIS. Here is one:
I used 54 Gem as my reference star 8 x 60s

54 Gem a3V reference.png (18.81 KiB) Viewed 6405 times

Notice that the noise you saw from 540 nm to 600 nm is now gone. This was removed by my flats correction.

I used this reference to calibrate my spectrum of Zeta Tauri 19 x 25 s

Zeta Tauri 12 30 2017.png (12.4 KiB) Viewed 6405 times

I thought it was interesting that I might see a double peak for H-alpha. Robin Leadbeater made the helpful suggestion that I pursue a smaller slit for the ALPY600 to improve the resolution.

Zeta Tauri halpha.png (12.78 KiB) Viewed 6405 times

I would also be very happy to share this data with you if you tell me how.

[etienne bertrand]

Very good results !!!!
You have mesure your resolution on your spectra ? I'm curious to konw it.

[James Ley]

I was able to process the spectrum of Beta Mon A with ISIS. Therefore this image is calibrated and corrected using 14 Lep as a nearby reference star. I think it is interesting to compare the single capture above with this average spectrum
Duration : 726.0 secondes
Resolution power : 516.3

Beta Mon A full.png (12.58 KiB) Viewed 6338 times

I looked at some echelle spectra of Beta Mon A and I could see many of the metal emission peaks that I see here. At high resolution, many were split into two peaks with the central absorption extending below the continuum. In my low resolution spectrum these peaks seemed broad or flat topped, with a few having a small dip in the middle. Again, I think a 9 um slit might be interesting. Here's a zoom of some of those emissions.

Beta Mon A zoom.png (11.64 KiB) Viewed 6338 times

[James Ley]

Here is the spectrum containing both Beta Mon B and C.
As I thought, I was unable to separate the two components, although they were visible in the image. The H-beta emission of Beta Mon C is gone, but the absorption has a weird bump. Next chance I get I'll rotate the slit to see if I can't get good spectra of B and C separately.
Duration : 1448.0 secondes
Resolution power : 553.0

Beta Mon BC.png (12.29 KiB) Viewed 6337 times

One of the (many) aspects of ISIS that I don't understand is the Binning Zone Adjustment. If I make it too narrow (even though the spectrum doesn't seem outside the range), my spectrum is sometimes unusable.

[Olivier GARDE]

One of the (many) aspects of ISIS that I don't understand is the Binning Zone Adjustment. If I make it too narrow (even though the spectrum doesn't seem outside the range), my spectrum is sometimes unusable.

Hi james,

The binning zone must contain all the spectrum and to be sure to take into account the whole spectrum (especially for the blue part) you must push the thresholds level of visualization.

Also the areas above and below the binning area (subtraction area of ​​the sky background) must contain no spectrum except for interstellar lines and lines of light pollution.

And of course the spectrum must be as horizontal as possible and at the same place for each individual exposure.

[James Ley]

Thank you Olivier,
That is very helpful. Can one change Y0, the position of the spectrum? What is the meaning of Ysup and Yinf?
ISIS is a wonderful program, but when I do something wrong, it betrays my ignorance.