Theoretical Data UCD Proposal

[Rob Seaman]

On Oct 24, 2007, at 7:45 AM, Brian Thomas wrote:

> On Wednesday 24 October 2007, Frederic V. Hessman wrote:
>
>>         IVOAT:stellarobjects            "stellar objects"
>
> OK, I'm not a theorist, but isn't that already handled by  
> IVOAT:star (??).
> Do we want to start getting in the business of aliased terms (beyond
> what already exist in the IAU Thesaurus)?

I would have thought that an ontologist would dote on splitting such  
hairs - well, not hairs precisely for objects in the range of 10^30  
kg, but you get the idea :-)

A star is like a planet in that we all want it to have a detailed  
definition, even if we disagree on those details.  For most of us,  
however, a star's energy budget includes nuclear reactions.  By such  
a definition, compact post-nuclear residue such as white dwarfs and  
neutron "stars" may be stellar objects, but are not stars.  Stellar  
objects in the 1 Msun range begin life as stars.  (I would think  
coalescing nebulae are not yet stellar objects.)  Objects in the  
10^-3 Msun range aren't stellar at all, but rather planets (whatever  
the heck that means).  Brown dwarfs would likely be considered  
stellar objects, but not stars.  Black holes are neither.  (A stellar  
object, like a quasi-stellar object, probably has to emit EM  
radiation.)  One would think stellar objects are subclassed from  
compact objects, and stars are subclassed from stellar objects.

Or maybe Rick meant something entirely different.  His fundamental  
point was that for his purposes such a distinction might make sense.   
For yours, perhaps not.

If we don't want to recognize aliases, perhaps we should have no  
interest in the IAU Thesaurus.

- Rob