On Thu, Apr 17, 2014 at 10:22:42AM -0400, Jeffrey Schwartz wrote:
> Imagine a black hole with a "hot" disk, and a planet with
> no-rotation (tidal lock, like the moon) in a very, very, very, very
> long ecliptic orbit, on the order of 250 years or so.

A tide-locked highly elliptical orbit?  One interesting feature of
those is that the tidal effects are almost completely dominated by the
close approach around periapsis.  So the planet would only present the
same face to the central body during that short period.  During the
rest of the orbit, it would continue to rotate at the same rate but
its orbit will be slower - so it will not continue to face the
primary.

For a highly elliptical orbit with apoapsis at 10x the distance of
periapsis, the ratio of angular velocities would be 100:1.  During
closest approach one side of the planet would be thoroughly burnt,
while the other only gets a lighter toasting on the way in and out.
Most of the rest of the orbit would be spent in the dark and cold.

> The "sun-side" of the planet takes a continued splatter of X-rays,
> which hit sundry elements inside the core and heat it

Although X-rays do penetrate matter to some extent, they do not get
far on a planetary scale.  Virtually none will get through the top few
metres.

> The planet was the home of a TL6 race at one point, which realized
> what was about to happen, and created deep, deep shelters since they
> had no space flight capability. This did them no real good, but it did
> allow a lot of bacteria, spores, fungus, and some insects to survive.

By "what was about to happen", do you mean the regular every-250-years
toasting, or was there some astronomical event (e.g. a passing star)
that disrupted the planet's orbit into such a highly elliptical state?

In the former case I'd expect that their ancestors must have had some
way to deal with the situation last time, whether they knew about it
or not.  (Likewise for the rest of the life on the planet)

- Tim