<p>It can tell you the chemical composition of the star. what elements are present and this can help you tell other things about the star. For example, the oldest stars are metal poor meaning they formed earlier in the history of the universe. Younger stars are expected to have more metal in them.</p>
<p>Also the energy of the spectral lines of the elements are well known. From the spectra of a star we can measure the shift in the spectral lines and from that we can determine the doppler shift and the stars velocity relative to earth.</p>

CC BY-SA 4.0
2020-07-18T04:57:10.367Z
perhaps mention that we can learn about the [interstellar medium](https://en.wikipedia.org/wiki/Interstellar_medium#The_atomic_hydrogen_model) that's between it and us as well?
uhoh
CC BY-SA 4.0
2020-07-18T03:17:19.713Z
2020-07-18T03:23:48.263Z
2020-07-18T03:23:48.263Z
Natsfan
<p>Stellar spectra contain both emission and absorption lines. What can these lines from a star's spectrum tell us?</p>

CC BY-SA 4.0
2020-07-18T02:10:26.600Z
Given enough context, its chemical composition, its distance, its age, its radial motion, and probably some other stuff I'm not thinking of.
Brian Tung
CC BY-SA 4.0
2020-07-18T02:33:23.980Z
It could tell you that helium exists, and if you were willing to do a little work it could tell you what $$\frac{m_e e^4}{8 \epsilon_0^2 h^2}$$ equals.
uhoh
CC BY-SA 4.0
2020-07-18T02:43:11.783Z
What is e and h here.
Oop
CC BY-SA 4.0
2020-07-18T03:26:14.390Z
What did you find out before you asked your question here? Please edit your question to add more detail, so that an answer can focus on the exact issue your initial research was unable to resolve. :-)
Chappo Hasn't Forgotten
CC BY-SA 4.0
2020-07-18T04:54:01.413Z
@Oop Sorry, I made a very obscure joke. That's the [Rydberg constant](https://sco.wikipedia.org/wiki/Rydberg_constant) and there $e$ is the elementary charge unit and $h$ is the Planck constant. The idea is that by observing spectral lines, especially those of hydrogen, we can determine the energy levels of electrons in atoms. Of course I assume that your questions primarily asks what can be learned about a star, or the interstellar matter between it and us!
uhoh
<star><stellar-astrophysics>
What can a star's spectrum tell us?
Oop
# What can a star's spectrum tell us?

(Asked by: username_0 on 2020-07-18)

Stellar spectra contain both emission and absorption lines. What can these lines from a star's spectrum tell us?

**Tags:** star, stellar-astrophysics
> **Comments:**
> **username_1**: Given enough context, its chemical composition, its distance, its age, its radial motion, and probably some other stuff I'm not thinking of.  
> **username_2**: It could tell you that helium exists, and if you were willing to do a little work it could tell you what $$\frac{m_e e^4}{8 \epsilon_0^2 h^2}$$ equals.  
> **username_0**: What is e and h here.  
> **username_3**: What did you find out before you asked your question here? Please edit your question to add more detail, so that an answer can focus on the exact issue your initial research was unable to resolve. :-)  
> **username_2**: @Oop Sorry, I made a very obscure joke. That's the [Rydberg constant](https://sco.wikipedia.org/wiki/Rydberg_constant) and there $e$ is the elementary charge unit and $h$ is the Planck constant. The idea is that by observing spectral lines, especially those of hydrogen, we can determine the energy levels of electrons in atoms. Of course I assume that your questions primarily asks what can be learned about a star, or the interstellar matter between it and us!  

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## 1 answers

### Answer by username_4 on 2020-07-18. Score: 1

It can tell you the chemical composition of the star. what elements are present and this can help you tell other things about the star. For example, the oldest stars are metal poor meaning they formed earlier in the history of the universe. Younger stars are expected to have more metal in them.

Also the energy of the spectral lines of the elements are well known. From the spectra of a star we can measure the shift in the spectral lines and from that we can determine the doppler shift and the stars velocity relative to earth.

> **Comments:**
> **username_2**: perhaps mention that we can learn about the [interstellar medium](https://en.wikipedia.org/wiki/Interstellar_medium#The_atomic_hydrogen_model) that's between it and us as well?  

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