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Beta Lyrae in med/high resolution

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#1 Astrobodger

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Posted 15 May 2013 - 06:13 PM

I have been capturing Beta Lyrae spectra on my DIY spectrometer (1200 l/mm grating) to monitor what happens as this binary pair eclipse each other. The UK weather hasn't allowed me to capture data on as many nights as I wanted, but something is better than nothing.

 

Beta Lyr Ha IR.png

 

The lines are split due to rotation of the accretion disc (doppler effect). The helium seems to show this far more than Hydrogen. I will try and figure out how to calculate the rotation speed.

 

The DIY spectrometer used is actually still work in progress so the spectra quality will improve as I iron out a few issues.

Thanks for looking
John

 


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Celestron 8" F5 Newt on EQ5

Spectrographs 300 l/mm & 1200 l/mm, SA100

Mammut L429, Canon 1000d, Canon 450d

 

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#2 Astrobodger

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Posted 16 May 2013 - 10:22 AM

I have updated the chart with some quick and dirty calculations of radial velocity.

 

I have made what is possibly a naive assumption that I can use half the distance between each peak as Delta Lamda in the classic calculation. 

v = c x Delta Lamda/Lamda

 

I have posted this for confirmation on Ken Harrison's hardcore spectroscopy site.

 

Link to new chart
https://dl.dropboxus...ad Velocity.png

 

NB the bottom plot in the original chart was for 20th April not 20th May (being able to take spectra in the future would be quite an achievement ;) )

 

thanks for looking

John


Celestron 8" F5 Newt on EQ5

Spectrographs 300 l/mm & 1200 l/mm, SA100

Mammut L429, Canon 1000d, Canon 450d

 

http://uk.groups.yah...up/astrobodger/


#3 astrodoc71

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Posted 17 May 2013 - 09:17 AM

Very cool stuff John! This is an extremely complex system. If the pros can't understand it, then I have little hope...but I do have a couple of questions for you.

1) The emission peaks both pertain to the accretion disc, so you are just seeing the disc moving toward us and away from us at the same time (since they show up in the same graph)? This is the reason for the double peaks? Do we know why the hydrogen doesn't show it even though it is the more intense emssion?

2) This doesn't appear to tell us anything about the eclipsing companioin star? Wouldn't we want to measure the change in intensity of the emission over the period of the binary system to see the effects of the companion star? Isn't this something different than what you're doing here or are you able to see that with the data you have?

3)  Let's talk about the doppler effects. You have a pretty high resolution set up. Are you able to resolve the radial velocities of the 2 stars in the system. Right now you have the doppler phenomenon showing up in one plot. What about any changes between different days that would indicate movement of the stars around each other rather than just the disc rotating?

 

Thanks John!

Dave


daveandtelescope.wordpress.com


#4 Astrobodger

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Posted 17 May 2013 - 01:19 PM

Hi Dave,

 

You are right this is complex and an insane choice of target to tackle when you are tweaking a bodged spectrometer and also writing your own processing software to work with the new requirements of higher resolution spectroscopy. :wacko:

 

I started a thread on Ken Harrison's forum to get some input from experts (no offense intended to users of this forum!). This thread may answer some of your questions (and raise even more?).

 

http://tech.groups.y...py/message/7531

 

It seems you need a lot of knowledge to know which things to look at. You are correct that the Ha lines are doppler shifted due to the rotation of the disc.

 

Last night I used Si lines (as advised by Paulo on the other forum) to measure the actual radial doppler shift and got 0.29nm =137km/s.

 

SheliakVegaHa17May2013_b.png

 

cheers

John

 


Celestron 8" F5 Newt on EQ5

Spectrographs 300 l/mm & 1200 l/mm, SA100

Mammut L429, Canon 1000d, Canon 450d

 

http://uk.groups.yah...up/astrobodger/


#5 astrodoc71

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Posted 18 May 2013 - 11:39 AM

That's really great John! So it seems from that discussion you referenced on the astronomical spectroscopy group that the Si lines do in fact reflect the relative velocities of the 2 component stars in the binary system and not just the accretion disc? Excellent work!

That Gif animation is fantastic and I have posted that link here for the readers as this is basically what I was referring to before, namely the change in intensity of the emission lines as the one star eclipses the other! Even though the intensities are not consistent from one period to the next I think it might still be fun for those of us with the SA100 to see what happens, maybe reproduce a gif animation of our own!

http://quasar.teoth....ies/02_full.gif

 

Thanks again!

Dave


daveandtelescope.wordpress.com


#6 gasman

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Posted 18 May 2013 - 08:37 PM

Highly interesting John. How come you show just the silicon lines shifted but not all the others? is it because the O2 and H20 is local to us?

 

Steve



#7 Astrobodger

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Posted 24 May 2013 - 03:24 PM

That's right Steve.

 

The O2 and H20 are absorption lines caused by the Earth's atmosphere. There can be very convenient for calibration purposes at higher resolutions. Easier that using a Neon calibration lamp that I have started to play with.

 

cheers

John


Celestron 8" F5 Newt on EQ5

Spectrographs 300 l/mm & 1200 l/mm, SA100

Mammut L429, Canon 1000d, Canon 450d

 

http://uk.groups.yah...up/astrobodger/






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