<p>If the wavelength of K Ca II is 393,4 nm and the weight of a calcium atom is  6.66e-26 kg, then how do I find Δλ?</p>
<p>This is what I've tried so far:</p>
<p><a href="https://i.sstatic.net/DWjWz.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/DWjWz.jpg" alt="this is what ive tried so far" /></a></p>

CC BY-SA 4.0
2022-03-09T15:59:09.507Z
Hi Samuel, it will be easier, or at least more more likely to be helpful, if you describe how you have tried so solve this problem so far. As the question stands now, it looks a bit like "do my homework", which is not really what this site is for.
pela
CC BY-SA 4.0
2022-03-10T01:56:53.637Z
Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
Community
CC BY-SA 4.0
2022-03-10T16:14:23.350Z
@pela hi! I'm sorry that I made it seem like a do my homework question, I've just been looking for an equation that would help me solve Δλ with the information I have. I have tried an equation (updated my post with it) although I'm not sure if that's the right one I'm looking for, as im not entirely sure if it calculates the actual Δλ  or just the line width. Thank you in advance!
Samuel Adámek
CC BY-SA 4.0
2022-03-21T10:30:20.053Z
No worries, but I still think your question would benefit from some details that doesn't require us the interpret your equations. You're also encouraged to write them in text (mathjax) rather than an image, since images can't be searched. But I think you're on the right track, probably just need to fiddle terms around. The thermal velocity dispersion is $v_\mathrm{th}=\sqrt{2k_\mathrm{B}T/m}$, the frequency shift is $\Delta\nu=\nu_0 v_\mathrm{th}/c$, and the wavelength shift should then be $\Delta\lambda=c/\nu_0^2\times\Delta\nu$.
pela
<spectroscopy><doppler-effect>
How do I find thermal doppler line broadening for a K Ca II line in a star at 3000K?
Samuel Adámek
# How do I find thermal doppler line broadening for a K Ca II line in a star at 3000K?

(Asked by: username_0 on 2022-03-09)

If the wavelength of K Ca II is 393,4 nm and the weight of a calcium atom is 6.66e-26 kg, then how do I find Δλ?

This is what I've tried so far:

[![this is what ive tried so far](https://i.sstatic.net/DWjWz.jpg)](https://i.sstatic.net/DWjWz.jpg)

**Tags:** spectroscopy, doppler-effect
> **Comments:**
> **username_1**: Hi Samuel, it will be easier, or at least more more likely to be helpful, if you describe how you have tried so solve this problem so far. As the question stands now, it looks a bit like "do my homework", which is not really what this site is for.  
> **username_2**: Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.  
> **username_0**: @pela hi! I'm sorry that I made it seem like a do my homework question, I've just been looking for an equation that would help me solve Δλ with the information I have. I have tried an equation (updated my post with it) although I'm not sure if that's the right one I'm looking for, as im not entirely sure if it calculates the actual Δλ  or just the line width. Thank you in advance!  
> **username_1**: No worries, but I still think your question would benefit from some details that doesn't require us the interpret your equations. You're also encouraged to write them in text (mathjax) rather than an image, since images can't be searched. But I think you're on the right track, probably just need to fiddle terms around. The thermal velocity dispersion is $v_\mathrm{th}=\sqrt{2k_\mathrm{B}T/m}$, the frequency shift is $\Delta\nu=\nu_0 v_\mathrm{th}/c$, and the wavelength shift should then be $\Delta\lambda=c/\nu_0^2\times\Delta\nu$.  

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## 0 answers

