MadSci Network: Astronomy
Query:

Re: Have all the stars in a 100 light year radius been mapped

Date: Tue Feb 19 09:26:12 2002
Posted By: Steve Cartoon, Web Engineer
Area of science: Astronomy
ID: 1012926836.As
Message:

G'day!
   While it is possible that all the stars of magnitude 5.0 and less 
within a 100 light-year have been mapped (that is, the ones visible to the 
naked eye), it is definite that all the stars within 100 light-years have 
NOT been mapped.
   Dunno if you were interested in astronomy back in 1996, but it was 
about that time that the first extra-solar planets were being tracked. 
About that same time a big argument emerged over a new type of observed 
stellar body called a brown dwarf. The argument essentially was about the 
largest size one of these brown dwarves could be and still be technically 
called a planet (1 to 10 times the size of Jupiter is still a planet, 10-
80 times the size of Jupiter are brown dwarves, larger objects than this 
tend to ignite into stars).
   Brown dwarves do not emit very much light at all. In fact, the way that 
the one circling Gliese 229 (one of the first, I think) was detected was the 
light from the parent star reflecting off the brown dwarf. Others have 
been detected blocking the view or bending light around other more-visible 
stellar objects. The Orion Nebula is supposed to have quite a number of 
brown dwarves. More and more reports are coming in which state that there 
are lots and lots of these brown dwarves, and that they could account for 
some of the matter supposedly missing from the universe.
   From this, it's easy to conclude that there are free-standing brown 
dwarves out there, quite possibly with their own miniature solar systems 
(much like Jupiter), and that their near-lightlessness would make them 
practically impossible to detect with modern astronomical equipment.
   So, the answer to your question is quite definitely NO (at least for 
most of this century).
   And there's also rogue planets (spun off from dying nova stars) and 
really big dead space rocks (asteroids and planetoids) out there that are 
so cold they can't even be detected unless they cross the path of 
something else that was visible. That's not really part of an answer to 
your question, but they're out there too.

   I hope this helps you somewhat. Good luck to you!

   Steve Cartoon
   Former Internet Software Engineer, Edmark.com





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