"Margo Schulter" wrote in message
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I also submit that the closest know planets to Pollux are Neptune or
Pluto,
depending on the time and/or the French IAU's planet definition for this
week.

An interesting question, which has come up in other threads, is how the
current Resolution 5A should be read in terms of extrasolar planets. One
position I've seen suggested is that an earlier IAU document regarding
extrasolar planets (2001 or so? -- actually, last revision, 2003) might
still apply.

Thus see:

http://www.dtm.ciw.edu/boss/definition.html

Curious, that means a planet ejected from a binary
system ceases to be a planet and becomes a
"sub-brown dwarf". Calling it a planet and
qualifying that as "free-floating" would seem more
logical. That said, my own suggestion (below) has
the same effect.

For a list of candidate extrasolar planets, interestingly dated
28 August 2006, or four days after the adoption of Resolution 5A,
see:

http://www.dtm.ciw.edu/boss/planets.html

....

Try, of course, and George Dishman and I have been having a lively debate
on just whether and how Resolution 5A might effect extrasolar planets.
I tend myself to assume that the earlier document expressly on these
planets might still more or less hold.

I have now drafted an attempt at a more general
classification scheme. I first tried to draw the
current IAU version for reference though the
situation of satellites is a little tricky when
using the literal wording. Anyway this is what I
produced:

http://www.georgedishman.f2s.com/astronomy/IAU.png

I then tried to adjust that minimally to add the
extra-solar possibilities but it ended up with
quite a bit different. I have substituted two
names, "planetesimal" instead of "dwarf planet"
to remove the linguistic difficulty and "asteroid
or comet" instead of "small solar-system body". In
hind sight it would have been better to say just
"asteroid" as the intention is that is be expanded
by footnote to include various types such as TNOs
KBOs, QB1'os, comets, etc.. Basically everything
smaller than a dwarf planet but larger than dust.
Anyway, here it is:

http://www.georgedishman.f2s.com/astronomy/GAD.png

I would appreciate your comments. I foresee possibly
contentious areas (other than name selection which
I consider unimportant compared to the criteria)
being the inclusion of brown dwarfs as a type of star
and the use of "planemo" (which you prompted) whether
the object is in orbit or not. I have restricted the
use of planet to those with a stable orbit to comply
with the IAU suggestion that it should have cleared
its neighbourhood since that cannot be determined in
say a chaotic ternary system or if the object is
free-floating.

best regards
George