In article ,
Andrew Usher writes:
... while a super AGB star can reach up to ~100,000
Lsun or Mbol ~ -8 (from memory, anyway - it's something like that).

However, it seems these thermally pulsing stars will be obscured by
dust. I'm not entirely sure why, given that lower-mass giants are not,

Any star that's losing mass will likely have dust condense in the
outflow. The exception would be if the outflow is low density and
very fast, so density becomes too low at the radius where dust would
be cool enough to condense. However, even novae and supernovae (some
of them, anyway) show dust condensation, though the solar wind, for
example, does not.

There are plenty of "extreme carbon stars" with luminosities around
10^5 solar. Think of CW Leo or LL Peg, for example. (Other names
that might be more familiar to some are IRC +10216 and AFGL 3068,
respectively.) One recent paper is by Speck et al. (2009 ApJ 691,
1202). References in it will probably lead you to the extensive
literature on the subject, or you could just put the phrase quoted
above into ADS and see what appears.

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