<p>Wikipedia has a <a href="https://en.wikipedia.org/wiki/Stellar_classification#Spectral_peculiarities" rel="nofollow noreferrer">pretty comprehensive list</a> of all these peculiarities and their meaning. Spectral classification also is not always unique or unambiguous.</p>
<ul>
<li>&quot;/&quot; denotes stars which could be classified as either</li>
<li>&quot;...&quot; denotes undescribed peculiarities</li>
<li>&quot;+&quot; denotes hypergiants. But see there also for deviating use of &quot;f+&quot; or &quot;(f+)&quot;.</li>
<li>&quot;:&quot; denotes uncertain spectral classification</li>
<li>C,N,O, (any element symbol) denotes particularily strong lines from that element(s)</li>
</ul>
<p>That said, any catalogue might want to explain uncommon nomenclature in its notes.</p>

CC BY-SA 4.0
2022-07-01T12:35:44.243Z
2022-07-01T12:35:44.243Z
planetmaker
<p>I'm collecting different star catalogs I've found in the Internet to make my own and I noticed some &quot;strange&quot; peculiarity in how those catalogs describe spectral type of a star.</p>
<p>Namely:</p>
<ul>
<li>sometimes the type has got a slash like &quot;G8/K0III&quot;. Does it mean it is a binary star system? A variable star? A measurement uncertainty?</li>
<li>other types has an ellipsis: &quot;K0...&quot;. This one is a completely mystery to me...</li>
<li>you can find even &quot;+&quot; and &quot;:&quot;</li>
<li>and the last but not least: plain weird names like &quot;K1IIICN...&quot;</li>
</ul>
<p>May someone explain where those enigmatic descriptions come from? What in the way a spectral type is determined in observatories makes the need of such things?</p>

<star-catalogues><spectral-type>
Strange spectral types in star catalogs
Felix.leg
# Strange spectral types in star catalogs

(Asked by: username_0 on 2022-07-01)

I'm collecting different star catalogs I've found in the Internet to make my own and I noticed some "strange" peculiarity in how those catalogs describe spectral type of a star.

Namely:

* sometimes the type has got a slash like "G8/K0III". Does it mean it is a binary star system? A variable star? A measurement uncertainty?
* other types has an ellipsis: "K0...". This one is a completely mystery to me...
* you can find even "+" and ":"
* and the last but not least: plain weird names like "K1IIICN..."

May someone explain where those enigmatic descriptions come from? What in the way a spectral type is determined in observatories makes the need of such things?

**Tags:** star-catalogues, spectral-type


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## 1 answers

### Answer by username_1 on 2022-07-01. Score: 4 | Accepted answer

Wikipedia has a [pretty comprehensive list](https://en.wikipedia.org/wiki/Stellar_classification#Spectral_peculiarities) of all these peculiarities and their meaning. Spectral classification also is not always unique or unambiguous.

* "/" denotes stars which could be classified as either
* "..." denotes undescribed peculiarities
* "+" denotes hypergiants. But see there also for deviating use of "f+" or "(f+)".
* ":" denotes uncertain spectral classification
* C,N,O, (any element symbol) denotes particularily strong lines from that element(s)

That said, any catalogue might want to explain uncommon nomenclature in its notes.


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