GMS@PSUVM.BITNET (12/17/84)
I believe that there is some controversy surrounding the apparant discovery of a 'planet' orbiting another star in Ophiuchus. The controversy is not concerning the object itself, for it is most certainly there, but rather what to call it. To be rather picky about names, this object should be termed a 'brown dwarf' rather than a planet. Current theories of solar system formation include the probable existance of such objects. It could be still condensing, and may one day shed its outer atmosphere to shine (albeit faintly) as a red dwarf star. With an upper-atmosphere temperature of about 2000 degrees (Farenheit, Celsius or Kelvin???) this object is certainly undergoing fusion at its center. It has been speculated that if the planet Jupiter were more massive (I believe by a factor of four) that it too would generate enough contraction heat to ignite thermonuclear reactions, and hence become a star. (Does that make it a semi-protostar?) At any rate, I am mentioning this nitpicky argument primarily in response to some people who have said that the nitpicky argument is really being generated by astronomers who are jealous at not having found the first planet themselves. I disagree. I have been fortunate enough to work with the astronomers at Allegheny Observatory, who are in the process of searching for planets with a new instrument that achieves astrometric measurements of unprecidented precision, enough to accurately scan near space (up to about 10 parsecs) for even Earth-sized planets. (Assuming other factors too numerous to mention here.) Although I applaud the achievements of the astronomers who discovered the first 'brown dwarf', lets recognize it for what it is. The brown dwarf is no more a planet than were the rings of dust discovered by IRAS around Vega and Fomulhaut. The discovery of the brown dwarf, DOES lend even more observational evidence to current theories of star and solar system formation, and lends support to the argument that there may be planets surrounding most stars. ------------------------------------------------------------------------------ Gerry Santoro Microcomputer Information and Support Center GMS @ PSUVM (bitnet) Penn State University !psuvax1!santoro (UUCP) 101 Computer Building santoro @ penn-state (CSNET) University Park, PA 16802 (814) 863-4356
amra@ihuxj.UUCP (Steven L. Aldrich) (12/18/84)
{....Reality Wow, What A Concept! }
Gerry,
Thanks for the information about the Non-Planetary Mass orbiting VB-8.
I had thought this "object" was a bit "strange" to be a planet. I wonder
why the "news-media" didn't do a more "professional" job of reporting
the FACTS/DATA Correctly, instead of their hack-job on this discovery.
I would have been just as "excited" about the story personally, if it
had been accurately reported. The discovery of a Brown-Dwarf is also an
important mile-stone in this type of astronomy, as you point out.
BTW, the Temp. figures I quoted were in degrees F. not K or C, in case
you wanted to know. I was wondering if you'd be kind enough to supply
some additional input on a related matter?
Namely, what is the "upper-limit" for a planet's Mass & Temp. according
to the theorists? Isn't it somewhere just above Jupiter's figures? I'm
sure others would be interested in this info, so please Post any reply
in this matter. Thanks Again Gerry for your Kind, informative reply to
my recent ramblings! Merriest of Holidays.......
Peace & Best Wishes From:
The Atoms Currently Associated As
Steve Aldrich (ihnp4!ihu1n!amra) <=== New Address!
P.S. If you Can Not reach me at my New path, try the Old one
===> IHNP4!IHUXJ!AMRA <====
It may still be forwarding E-Mail to me for the next 1-2 weeks.rivers@seismo.UUCP (Wilmer Rivers) (12/20/84)
In article <1352GMS@PSUVM>, GMS@PSUVM.BITNET writes: > I believe that there is some controversy surrounding the apparant > discovery of a 'planet' orbiting another star in Ophiuchus. The controversy > is not concerning the object itself, for it is most certainly there, but > rather what to call it. > > To be rather picky about names, this object should be termed a 'brown > dwarf' rather than a planet. Current theories of solar system formation > include the probable existance of such objects. It could be still > condensing, and may one day shed its outer atmosphere to shine (albeit > faintly) as a red dwarf star. Has the IAU, or any other such body, adopted a formal definition of what is a "star", and what is a "planet"? This "brown dwarf" definition seems to rest on the distinction that it is a star because fusion is going on in the core. However, it should be noted that deuterium fusion takes place at a much lower temperature than does hydrogen fusion, and it has been speculated (sorry, I don't remember the references) that Jupiter may have had enough energy released by gravitational contraction to burn deuterium at one time. Even now, Jupiter emits more energy than it receives from the sun; does this qualify it to be a "star", albeit one that has entered a post-fusion "dwarf" stage ? The intuitive dis- tinction between stars and planets is that stars are (ionized) gas, whereas planets have a solid (Moon), liquid (Enceladus ?), or metallic (Jupiter ?) core. Even this idea, however, does not correctly consider the interiors of those dwarfs which are (or which at one time were) unarguably "stars" but which are now cool. [Note that in the limiting case of nuclear matter, neutron stars have cm-tall "mountains" and undergo "starquakes".] So just what is the official distinction between stars and planets ?
sharp@noao.UUCP (Nigel Sharp) (12/21/84)
> I believe that there is some controversy surrounding the apparant > discovery of a 'planet' orbiting another star in Ophiuchus. The controversy > is not concerning the object itself, for it is most certainly there, but > rather what to call it. > > To be rather picky about names, this object should be termed a 'brown > dwarf' rather than a planet. Current theories of solar system formation > include the probable existance of such objects. ... ... Hear hear ! I hesitated to say anything about this, for reasons below. > With an upper-atmosphere temperature of about 2000 degrees (Farenheit, > Celsius or Kelvin???) this object is certainly undergoing fusion at its > center. ... ... Not certainly. A very interesting debate is in progress about the exact behaviour of low-mass stars, and precisely when nuclear burning sets in. I favour the existence of nuclear burning in such an object, making it clearly not a planet. It is worth noting that there ARE definitions of planets (by quite reputable people) which would exclude the Earth (no internal power generation is one criterion which would exclude us, unless you insist on some sort of "significant" qualifier). However, the VB8B results is very interesting: it's just not what most people would term a planet (recent comment "if I flew a layman past it, he'd call it a star"). > At any rate, I am mentioning this nitpicky argument primarily in response > to some people who have said that the nitpicky argument is really being > generated by astronomers who are jealous at not having found the first > planet themselves. ... ... Precisely why I have been silent. > Although I applaud the achievements of the astronomers who discovered > the first 'brown dwarf', lets recognize it for what it is. The brown dwarf > is no more a planet than were the rings of dust discovered by IRAS > around Vega and Fomulhaut. > Gerry Santoro > Microcomputer Information and Support Center GMS @ PSUVM (bitnet) |||||| No axe to grind ! -- Nigel Sharp [noao!sharp National Optical Astronomy Observatories]