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What is this spectrum I took?

  1. Feb 22, 2012 #1
    I was taking solar spectra yesterday for a Physics lab, and I found this strange phenomenon slightly to the left of the sun. I think it might be a solar prominence, but then again I know absolutely nothing about astronomy. What is it?

    (The graph is intensity vs. wavelength)


    EDIT: I can't get the image to show, but the link is http://imgur.com/FfZxd. The absorption peaks are at 760.15 nm and 761.18 nm.
    Last edited: Feb 22, 2012
  2. jcsd
  3. Feb 22, 2012 #2


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    How far to the left are we talking about here? A few arcseconds?
  4. Feb 22, 2012 #3


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    here's the image for easy viewing :)



    Attached Files:

  5. Feb 22, 2012 #4
    Never mind, it turns out it's probably just the cheap spectrometer giving faulty readings. No strange solar phenomena today.
  6. Feb 22, 2012 #5


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    No worries! Keep up the experiments!
  7. Feb 25, 2012 #6
    The features seen at ~690, 720 and 760nm are due to absorption of the sunlight by molecules (water, I think) in the Earth's atmosphere. They are otherwise known as telluric absorption features.
  8. Feb 27, 2012 #7

    If the spectrographic data is properly normalized and calibrated (obviously it is not), then those would be O2 lines. Now, do you think that molecular oxygen might exist in a G-type star? If not, where might molecular oxygen exist between your telescope and the sun?

    Also, looking at the data, I am not convinced the wavelengths are accurate. You should be able to calculate what the peak energy output from the sun is from Wein's displacement law. If the wavelengths are off, then that might be H2O instead of O2. Now, where could H2O exist? In the sun's atmosphere? Probably not.
  9. Feb 27, 2012 #8
    I am not sure if these questions are directed at me, but I'll answer anyway. The wavelength calibration looks okay to me. The Calcium H & K lines appear to be located at their expected positions (393.4 and 396.9nm), as do the Sodium D line (~589nm) and the hydrogen alpha (656.3nm), to name just a few.

    Also, the telluric features are labelled in the solar spectrum shown on that wiki page.
  10. Feb 28, 2012 #9
    It was directed at the OP, but I just looked at some spectra of various objects I took last year and I guess I was misremembering the O2 lines being weaker than the H2O lines (except for Saturn, where H2O was almost as strong as O2, which may be partially due to extraterrestrial O2 combining with atmospheric O2).
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