<p>Metals have many electrons and many energy transitions available, therefore they are more likely to interact with photons (they increase the opacity). As a consequence, a star with higher metallicity will experience stronger winds, driven by the metal lines, that lead to a higher mass loss rate.</p>
<p><a href="https://i.sstatic.net/wwbDr.png" rel="noreferrer"><img src="https://i.sstatic.net/wwbDr.png" alt="the mass of a star as a function of time" /></a>
This plot from <a href="https://arxiv.org/abs/1809.09130" rel="noreferrer">Mapelli (2018)</a> shows the mass of a <span class="math-container">$90 M_\odot$</span> star as a function of time, for different metallicities. The higher <span class="math-container">$Z$</span>, the more dramatic is mass loss.</p>
<p>This of course influences the mass of the black holes that can be produced. If at the end of its life, a star has retained only a small fraction of its initial mass, it will form a black hole much smaller than if it had not lost mass. And if the mass loss has been so dramatic that the mass of the compact remnant is below the <a href="https://en.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E2%80%93Volkoff_limit" rel="noreferrer">Tolman-Oppenheimer-Volkoff limit</a>, the result might be a neutron star instead of a black hole.</p>
<p>This is the main reason why the likelihood of forming a black hole decreases with metallicity. High metallicity stars can loose enough mass during their life, that they are more likely to form a neutron star.</p>
<p>Useful reference: <a href="https://iopscience.iop.org/article/10.1086/375341" rel="noreferrer">Heger et al. (2003)</a></p>

CC BY-SA 4.0
2022-09-12T07:31:12.263Z
So just to make this 100% clear in my mind. A stars matter is like a sail to the photons, metallicity is like plugging any potential holes in that sail to increase it's capture of the wind?
TheJeran
CC BY-SA 4.0
2022-09-12T14:46:00.427Z
@TheJeran Yes, it is a good analogy
Prallax
CC BY-SA 4.0
2022-09-10T22:50:56.237Z
2022-09-11T06:45:34.833Z
2022-09-11T06:45:34.833Z
Prallax
<p>Large stars collapse and if they are large enough form black holes. But the likelihood reduces with metallicity.</p>
<p><a href="https://i.sstatic.net/iA0cF.png" rel="noreferrer"><img src="https://i.sstatic.net/iA0cF.png" alt="enter image description here" /></a></p>
<p>What mechanism facilitates this? I believe it has something to do with opacity and Eddiington luminosity but haven't been able to find a source that pulls the information together in a conceptual manner.</p>

CC BY-SA 4.0
2022-09-10T11:14:27.300Z
Please provide proper attribution for that image. It looks similar to https://commons.wikimedia.org/wiki/File:Supernovae_as_initial_mass-metallicity.svg
PM 2Ring
CC BY-SA 4.0
2022-09-10T11:17:45.533Z
Related question (with the same diagram): https://astronomy.stackexchange.com/q/12707/16685 but the answers there don't give any details on the role of metallicity.
PM 2Ring
<black-hole><supernova><metallicity>
How does metallicity reduce the likelihood of black hole formation?
TheJeran
# How does metallicity reduce the likelihood of black hole formation?

(Asked by: username_0 on 2022-09-10)

Large stars collapse and if they are large enough form black holes. But the likelihood reduces with metallicity.

[![enter image description here](https://i.sstatic.net/iA0cF.png)](https://i.sstatic.net/iA0cF.png)

What mechanism facilitates this? I believe it has something to do with opacity and Eddiington luminosity but haven't been able to find a source that pulls the information together in a conceptual manner.

**Tags:** black-hole, supernova, metallicity

> **Comments:**
> **username_1**: Please provide proper attribution for that image. It looks similar to https://commons.wikimedia.org/wiki/File:Supernovae_as_initial_mass-metallicity.svg  
> **username_1**: Related question (with the same diagram): https://astronomy.stackexchange.com/q/12707/16685 but the answers there don't give any details on the role of metallicity.  

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## 1 answers

### Answer by username_2 on 2022-09-10. Score: 6 | Accepted answer

Metals have many electrons and many energy transitions available, therefore they are more likely to interact with photons (they increase the opacity). As a consequence, a star with higher metallicity will experience stronger winds, driven by the metal lines, that lead to a higher mass loss rate.

[![the mass of a star as a function of time](https://i.sstatic.net/wwbDr.png)](https://i.sstatic.net/wwbDr.png)
This plot from [Mapelli (2018)](https://arxiv.org/abs/1809.09130) shows the mass of a $90 M\_\odot$ star as a function of time, for different metallicities. The higher $Z$, the more dramatic is mass loss.

This of course influences the mass of the black holes that can be produced. If at the end of its life, a star has retained only a small fraction of its initial mass, it will form a black hole much smaller than if it had not lost mass. And if the mass loss has been so dramatic that the mass of the compact remnant is below the [Tolman-Oppenheimer-Volkoff limit](https://en.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E2%80%93Volkoff_limit), the result might be a neutron star instead of a black hole.

This is the main reason why the likelihood of forming a black hole decreases with metallicity. High metallicity stars can loose enough mass during their life, that they are more likely to form a neutron star.

Useful reference: [Heger et al. (2003)](https://iopscience.iop.org/article/10.1086/375341)

> **Comments:**
> **username_0**: So just to make this 100% clear in my mind. A stars matter is like a sail to the photons, metallicity is like plugging any potential holes in that sail to increase it's capture of the wind?  
> **username_2**: @username_0 Yes, it is a good analogy  

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