There are many terms from classic and modern SF that remain unresearched, and the Historical Dictionary of Science Fiction will be continually updated, especially as additional resources are put online. Boing Boing is syndicating new entries from the HDSF on a regular basis. (Read the series introduction.)
Rigellian (noun, adjective, and the language)
We have discussed demonyms on several occasions: these are words that refer to people from a particular place. Given the very large number of stars in the universe, there is an effectively unlimited supply of possible places where aliens can live; deciding which real (or fictional) worlds could be inhabited, and thus could generate demonyms, is a difficult task.
However, there aren't that many stars having well-known names, and SF writers have been positing inhabitants of their (perhaps nonexistent) planetary systems for many decades. We have entries for Aldebaranian, Alpha Centurian, Betelgeusean, Sirian, and Tau Cetan, all from the 1930s or earlier, and we have draft entries for many others, including Altairian, Arcturan, Denebian, and Fomalhautian.
Today's entry is the cluster of terms named after Rigel, the blue supergiant in the constellation Orion. There are, as usual, three related entries, for the noun, denoting an inhabitant of the system; the adjective; and the (rare) noun referring to the language of Rigellians. The main noun and adjective both date from the 1930s, and remain in use to the present day. Between this and Betelgeuse, we've probably exhausted the main candidates from Orion (not many people are writing about the natives of Bellatrix or Alnilam, the third- and fourth-brightest stars in that constellation), so whatever's next, it'll be time to move on.