<p>What is the double peak in this case, please? What does the third mean? Many thanks</p>
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CC BY-SA 4.0
2021-05-28T00:30:01.373Z
There's hyperfine splitting and isotope differences (protons vs deuterium) http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hydfin.html  btw are these wavelengths reported for air or corrected for vacuum wavelength?
uhoh
CC BY-SA 4.0
2021-05-28T03:44:38.140Z
Thank you. So, 656.47 nm is the wavelength for H alpha? I am measuring V/R ratio. V is the third from the left and R the right one that is much lower? HOw can I find out whether these wavelengths are reported for air or corrected for vacuum wavelength? It is measured with a step of 0.03 A.
Elena Greg
CC BY-SA 4.0
2021-06-01T18:34:01.277Z
Whether it's corrected for vacuum or measured in air would depend on your source. The source of the data should tell you which it is and I don't think anyone here could help you figure that out without a lot more information about what your source is.
zephyr
CC BY-SA 4.0
2021-06-01T18:54:40.243Z
OK. Thank you for your explanation.
Elena Greg
<spectroscopy><spectra><stellar-astrophysics><h-alpha>
H alpha - double peak (Be star)
Elena Greg
# H alpha - double peak (Be star)

(Asked by: username_0 on 2021-05-27)

What is the double peak in this case, please? What does the third mean? Many thanks

[![enter image description here](https://i.sstatic.net/r6NV6.png)](https://i.sstatic.net/r6NV6.png)

[![enter image description here](https://i.sstatic.net/qY6nX.png)](https://i.sstatic.net/qY6nX.png)

**Tags:** spectroscopy, spectra, stellar-astrophysics, h-alpha
> **Comments:**
> **username_1**: There's hyperfine splitting and isotope differences (protons vs deuterium) http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hydfin.html  btw are these wavelengths reported for air or corrected for vacuum wavelength?  
> **username_0**: Thank you. So, 656.47 nm is the wavelength for H alpha? I am measuring V/R ratio. V is the third from the left and R the right one that is much lower? HOw can I find out whether these wavelengths are reported for air or corrected for vacuum wavelength? It is measured with a step of 0.03 A.  
> **username_2**: Whether it's corrected for vacuum or measured in air would depend on your source. The source of the data should tell you which it is and I don't think anyone here could help you figure that out without a lot more information about what your source is.  
> **username_0**: OK. Thank you for your explanation.  

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## 0 answers

