<p>The paper <a href="https://ui.adsabs.harvard.edu/abs/2003ApJ...588.1121S/abstract" rel="nofollow noreferrer">Sudarsky et al., 2003</a>, which the wikipedia article is based on, is probably outdated by now in two important aspects.<br />
1.) They used equilibrium chemistry i.e. a local theory of perfect, uniform mixing in the entire atmosphere and infinitely fast chemistry. This has been by now realized to be important to correct (<a href="https://ui.adsabs.harvard.edu/abs/2006ApJ...649.1048C/abstract" rel="nofollow noreferrer">e.g. Cooper&amp;Showman 2006</a> or <a href="https://ui.adsabs.harvard.edu/abs/2017ApJS..228...20T/abstract" rel="nofollow noreferrer">Tsai et al. 2017</a>) and leads to different behaviour in the spectrum of a planet.</p>
<p>2.) The line-lists they used were inaccurate for many molecules for hot worlds (<a href="https://ui.adsabs.harvard.edu/abs/2017MolAs...8....1T/abstract" rel="nofollow noreferrer">see e.g. Tennyson &amp; Yurchenko 2017</a>), particularly in the infrared. This would mainly be leading to different computations of the P-T profile primarily, but that of course impacts the emission spectrum and hence the 'Sudarsky class'.</p>
<p>While those effects are impactful, I am not aware of any paper that systematically tried to redo the classification work from 2003, hence we don't know how impactful they would be overall.</p>

CC BY-SA 4.0
2023-04-19T00:14:39.410Z
Class-3 seems right at least, judging by that one exoplanet whose colour we know: https://exoplanets.nasa.gov/resources/139/nasas-hubble-finds-a-true-blue-planet/
Kazon
CC BY-SA 4.0
2023-04-18T11:25:30.200Z
2023-04-18T11:25:30.200Z
AtmosphericPrisonEscape
<p>How accurate is the <a href="https://en.wikipedia.org/wiki/Sudarsky%27s_gas_giant_classification" rel="nofollow noreferrer">Sudarsky scale</a> of gas-giant classification today? Do the different classes still exist, and look roughly the same?</p>

CC BY-SA 4.0
2023-04-17T14:03:26.737Z
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
<exoplanet><jupiter><optics><planetary-formation><neptune>
How accurate is the Sudarsky Scale today?
Kazon
# How accurate is the Sudarsky Scale today?

(Asked by: username_0 on 2023-04-15)

How accurate is the [Sudarsky scale](https://en.wikipedia.org/wiki/Sudarsky%27s_gas_giant_classification) of gas-giant classification today? Do the different classes still exist, and look roughly the same?

**Tags:** exoplanet, jupiter, optics, planetary-formation, neptune

> **Comments:**
> **username_1**: 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.  

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## 1 answers

### Answer by username_2 on 2023-04-18. Score: 3

The paper [Sudarsky et al., 2003](https://ui.adsabs.harvard.edu/abs/2003ApJ...588.1121S/abstract), which the wikipedia article is based on, is probably outdated by now in two important aspects.  
1.) They used equilibrium chemistry i.e. a local theory of perfect, uniform mixing in the entire atmosphere and infinitely fast chemistry. This has been by now realized to be important to correct ([e.g. Cooper&Showman 2006](https://ui.adsabs.harvard.edu/abs/2006ApJ...649.1048C/abstract) or [Tsai et al. 2017](https://ui.adsabs.harvard.edu/abs/2017ApJS..228...20T/abstract)) and leads to different behaviour in the spectrum of a planet.

2.) The line-lists they used were inaccurate for many molecules for hot worlds ([see e.g. Tennyson & Yurchenko 2017](https://ui.adsabs.harvard.edu/abs/2017MolAs...8....1T/abstract)), particularly in the infrared. This would mainly be leading to different computations of the P-T profile primarily, but that of course impacts the emission spectrum and hence the 'Sudarsky class'.

While those effects are impactful, I am not aware of any paper that systematically tried to redo the classification work from 2003, hence we don't know how impactful they would be overall.

> **Comments:**
> **username_0**: Class-3 seems right at least, judging by that one exoplanet whose colour we know: https://exoplanets.nasa.gov/resources/139/nasas-hubble-finds-a-true-blue-planet/  

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