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Have you ever wonder if there are any green stars?  I have, so I did a  
little research.

I remembered seeing Hubble and NASA pictures of certain emission and  
absorption nebulae with swaths of green colors and some of them with a  
few small green stars.

I also looked at NASA’s WISE survey picture of a green color  
star(scanning in infrared). NASA discovered this green ultra-cool  
brown dwarf called WISEPC JO45853.90+643451.9 in Camelopardalis or The  
Giraffe. The brown dwarf is position right on the neck of the Giraffe.

This brown dwarf has methane in atmosphere, which absorbs blue light  
and the dwarf is so faint that it does not give red light. Thus color  
green.

This week I decided to do some reading on subject. I found that some  
Brown dwarfs (some astronomers think of them as failed stars) can  
appear green.

Brown dwarfs are cool and dim and keep contracting until a form of  
pressure takes over-electron degeneracy pressure and these are called  
T dwarfs. Other brown dwarfs called L dwarfs fuse deuterium for very  
short periods of time.

The spectrum of some of these T dwarfs shows absorption bands of  
methane. Similar to spectra of Jupiter. NASA has detected tiny  
crystals circling around 5 brown dwarfs. The crystals are thought to  
be olivine (color green) thought to help seed formation of planets.

The presence of methane and green olivine crystal means that a dwarf  
star can appear to be green.

The problem is, are these real stars or just large planets. Most T  
dwarfs size is less than 13 Jupiter masses. Some are free-floating and  
formed on their own through gravitational contraction out of a cloud  
of gas-like normal stars.

Some astronomers classify L dwarfs as stars and T dwarfs as planets.

Gibor Basri UC at Berkeley proposed we call T dwarfs planemos  
(planetary mass objects) if they are at least massive enough to be  
spherical but not massive enough to be deuterium-fusing brown dwarfs.

How do we know that some T dwarfs (electron degeneracy pressure) were  
not L dwarfs (fused deuterium) at one time?

It is my belief that with advance technology we will start seeing more  
pictures of these green color dwarf stars.

I wouldn't jump for joy if you think (as an amateur astronomers)  
you’ll ever see a green star through your telescope.  That technology  
is way above our pay scale.

Ivo Rabell


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