Bright stars in the night sky traditionally have their own proper names, like "Sirus" or "Canopus".

Most stars don't have names, but instead catalogue identifiers, like the Bayer designation, Flamsteed number, Hipparcos id, etc. Those are not proper names.

What is the brightest star to not have a name?

Some findings and qualifiers, found through initial research:

  • The IAU has a Working Group on Star Names, with some 449 approved names, but this is still rather incomplete and does not reflect the full body of star names that are in regular use. "Official" is not a requirement for names to exist!
  • Another collection I found is the NASA technical memorandum 33-50 from 1971 containing 537 star names, by necessity including names not on the IAU list. Cited sources: "Becvar, A. , Atlas of the Heavens — II Catalogue 1950.0. Sky Publishing Corp. , Cambridge, Mass. , 1964.", "Smithsonian Astrophysical Observatory Star Atlas of Reference Stars and Nonstellar Objects. The M. I. T. Press, Cambridge, Mass. , 1969.", "Allen, R. H. , Star Names, Their Lore and Meaning. Dover Publications, Inc. , New York, 1963."
  • Names need only apply to naked eye inseparable systems as a whole. For instance, Capella B is one of the brightest stars in the sky, and does not have it's own name, but is visually indistinguishable from Capella A, and would thus be covered under the name "Capella".
  • The brightest star that is missing from lists with some regularity is Gamma Velorum, but this has the name "Regor" in common use. It's not an old name, merely half a decade and coined by the Apollo 1 astronauts. All names are ultimately "just made up by someone",the important part is whether other continue to use the name. A more traditional Arabic name is "Suhail al Muhlif", even though the "Suhail" name itself is rather ambiguous this would also count as a name.
  • Epsilon Centauri is called "Birdun" and Alpha Lupi is called "Men", both missing from many lists.

My best candidate so far is the star Eta Centauri, the 82nd brightest star in the sky according to the HYG database. Its Chinese name 庫樓二 does not count, since this is simply a catalogue number. But it may very well have a traditional name, I have just not been able to find it.

  • $\begingroup$ In order to answer this question, you would have to define a very strict naming standard. What appears as one star to they eye often turns out to be a double in a telescope. And even many of those turn out to be doubles as we get better and better catalogs. So there needs to be a consistent method of determining which stars are actually named. $\endgroup$ Dec 4, 2022 at 15:19
  • $\begingroup$ May we include variables at their peak brightness rather than minimum or average? $\endgroup$
    – James K
    Dec 4, 2022 at 16:17
  • $\begingroup$ @GregMiller I'm leaning towards the approach of treating the combined brightness of doubles, even optical doubles, as a single "star". Certainly, traditional names aren't going to distinguish those. $\endgroup$ Dec 4, 2022 at 16:33
  • $\begingroup$ @JamesK All three sound reasonable. Would this significantly change the answer? $\endgroup$ Dec 4, 2022 at 16:33
  • $\begingroup$ Eta Carina, doesn't have a proper name, but at maximum brightness it rivals Sirius. But it is very irregular. The last big flare was in 1845. The trouble is that by defining names as "used by others" will give rise to edge cases. Nobody really uses Saik,Sabik or Han to refer to Zeta Ophiuchi, but you can find all of these names in "lists of star names". There are a lot of stars in these lists in which fail the criteria "generally used by others". As you are looking at edge cases, the answers will all be eitther trick answers like "eta car" or stars like Zeta Ophiuchi $\endgroup$
    – James K
    Dec 4, 2022 at 16:50

1 Answer 1


Given reasonable interpretation of your criteria, Eta Centauri and Epsilon Centauri have almost identical apparent magnitudes and neither has a proper name.

However this answer is very sensitive to definitions. Not many people actually use (for example) "Kaus Australis" for the brightest star in Sagitarius. It isn't the common name, in the way that "Rigel" or "Sirius" is. But it does appear in catalogues of star names. It is not at all clear that "others continue to use this name". Perhaps so few people continue to use the name that it is effectively nameless.

On the other hand, I'm sure that you can find some culture that has names for these stars in the Centaur. There are plenty of indigenous sky cultures from south of the Equator. Doubtless some group has names for these stars, even if they are not recorded but are just private names used by the culture.

So whatever answer is given to this question will be an "edge" answer. Nevertheless, Eps Cen and Eta Cen are two possible answers that do make sense.


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