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ELEnin dwarf star and related threats are beginning to escalate and my August 1, 2011 safety windows could collapse at any moment, which means you need to keep your finger on the pulse of conditions until the time to bugout and meet up with your survival groups at your safe zone locations.
Brown Dwarf Comparison
Stars with less mass than the sun are smaller and cooler, and hence much fainter in visible light. Brown dwarfs are the smallest and coolest of stars. They have less than eight percent of the mass of the sun, which is not enough to sustain the fusion reaction that keeps the sun hot. These cool orbs are nearly impossible to see in visible light, but stand out when viewed in infrared. Their diameters are about the same as Jupiter's, but they can have up to 80 times more mass and are thought to have planetary systems of their own.
NASA - Brown Dwarf Comparison
Getting WISE About Nemesis(AstroBio)
These cool orbs are nearly impossible to see in visible light, but stand out when viewed in infrared. Their diameters are about the same as Jupiter's, but they can have up to 80 times more mass and are thought to have planetary systems of their own
Since methane can only exist at temperatures less than 1,200 K and the coolest stars have a surface temperature of 1,800 K, this is conclusive evidence that Gliese 229B is not a star. There remains, however, a possibility that it may be a very massive planet. The decisive factor is how GL 229B formed. If it condensed like a star from an interstellar cloud then it is certainly a brown dwarf. On the other hand, if it grew by accretion in a circumstellar disk, then some astronomers would argue that it is a large planet.
All brown dwarfs are planets.
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth. Brown dwarfs occupy the mass range between that of large gas giant planets and the lowest-mass stars; this upper limit is between 75 and 80 Jupiter masses (MJ). Currently there is some debate as to what criterion to use to define the separation between a brown dwarf and a giant planet at very low brown dwarf masses (~13 MJ ), and whether brown dwarfs are required to have experienced fusion at some point in their history. In any event, brown dwarfs heavier than 13 MJ do fuse deuterium and those above ~65 MJ also fuse lithium. Some planets are known to orbit brown dwarfs: 2M1207b, MOA-2007-BLG-192Lb, and 2MASS J044144b.
[Note added January 19, 2003: in this section, I originally mistakenly gave the brown dwarf a visual magnitude of 17, when in fact it's more like 25. This is a factor of about 1600 in brightness. I have made the correction in this section and fixed the math involved. While a factor of 1600 seems like a lot, it doesn't change my argument that if Planet X were a brown dwarf, it would be easily visible to the naked eye.]
A mature brown dwarf glows in infrared. It has a temperature of something like 1000 to 2500 degrees Celsius. An object that hot puts out very little visible light, but gives off more infrared. Not that they're all that bright: they are so faint that the first brown dwarf discovered, named Gliese 229b, eluded detection until 1995! It glows feebly at about magnitude 25 in visible light. That makes it roughly 1/40,000,000th the brightness of the faintest star visible to the unaided eye, and takes a fair sized telescope to see at all.
However (and this is a big however), Gliese 229b is a long way off: about 18 light years away, or roughly 200 trillion kilometers! If we go with Mr. Hazlewood's claim that Planet X is a brown dwarf, we can assume it is much like Gliese 229b. At a distance of even Pluto's orbit, Planet X would be a billion times brighter, glowing visibly at magnitude 2, making it a relatively bright star! Mind you, as I write this (July 2002) it must be significantly closer to us than Pluto, and proportionally brighter. It would be the third brightest object in the sky (only the Moon and Sun would be brighter). We don't see it, which leads me to the conclusion that it doesn't exist.
Because of the absorption of sodium and potassium in the green part of the spectrum of T dwarfs, the actual appearance of T dwarfs to human visual perception is estimated to be not brown, but the color of magenta coal tar dye.