Talarican,
Re: HARD SCIENCE ALERT! SENSITIVE PERSONS TAKE COVER!
I agree with you, since I've done an investigative essay on the subject (in fact, I continue to work on it--lately I had to fix errors in my hypothetical starflight mission profile, as the time dilation for the boost phases was off). Unpublished as of yet, but yes, all my working notes are scattered around here and Cave Canum.
As for the type of star, your comments are all on target--well, mostly. The "redness" is a bit slippery: it is actually a "pinkness," and we must remember that coloration of sunlight at the planetary surface is often 1) due to atmospheric contaminants, 2) a "hard science" mistake on the part of the author; but then again, "cannonical colors" ("G is for yellow," "M is for red") do not exactly match up to visual colors seen by human eyes looking through telescopes (examples: Aldebaran is K5 III, where "K is for orange," but it is a "pale rose" in visual color; Aludra is type B5 Ia, where "B is for almost white," but it is "pale red") and presumably this colored light falls onto the planets as well.
(Personally I think that the best candidates will be type G, in order to accomodate that 402 day year, where the days are around 30 hours each.)
It may be too harsh of me, but you forgot to mention that Urth has many of the same impossibilities with its primary (in terms of writer's craft, 5HC is a dry-run for some of the hardware in Severian's narrative: sky darker than light blue; twin planets; etc.). Since some would argue that the dying sun is a dingus not a dingo, that is, a sapient-modified luminary not a natrually-dying fireball, this hints tenuously that the C&A primary is a similar post-modification star.
At the very least it is a non-cannonical anomaly. Like some of those stars in the neighborhood that are simply too dim (for instance, the B companion of 85 Pegasi, which, according to some, is under-luminous by a factor of
15).
But what am I saying?! You don't even have the book, and presumably haven't read it yet!
=mantis=