Proxima Centauri Might Not Be the Closest Star To Earth

StartsWithABang writes The Alpha Centauri system consists of three stars, including Proxima Centauri, the closest star to Earth. But while main-sequence, hydrogen-burning stars are easy to find due to their visible light output, brown dwarfs — which only fuse the small amounts of deuterium they're born with — often emit no visible light at all, and can only be seen in the infrared. In 2013, WISE discovered a binary pair of brown dwarfs just 6.5 light years away, making them the third-closest star system to Earth, and leaving open the possibility that there may yet be brown dwarfs closer to us than any star, a question that it will take the James Webb Space Telescope to answer.

Comments

Are Brown Dwarfs Stars?

[jfdavis668]

I don't think brown dwarfs count as stars.

Re:Are Brown Dwarfs Stars?

[ShanghaiBill]

Okay, so it must be helium fusion going on in dwarfs then?

In stars like our sun, the main process is the proton-proton chain. Deuterium is produced, but it is then almost immediately fused with an additional proton into He3, which then undergoes additional fusion to form He4.

Stars bigger than 1.3 solar masses use the Carbon-Nitrogen-Oxygen Cycle to fuse hydrogen into helium in a reaction catalyzed by carbon.

White dwarfs have little material left to fuse. They are mostly carbon and oxygen, but they are not big enough or hot enough to fuse the carbon or oxygen into heavier elements. So they slowly cool off and die.

 

Re:Are Brown Dwarfs Stars?

[Neil Boekend]

The decay from white dwarf to black dwarf is slow. In fact it's so incredibly slow that the universe isn't old enough to have them in it yet.
Estimates for the time it takes are 10^15 to 10^37 years, depending on factors like pronton decay and WIMP existence. The universe is "only" 13.8*10^9 years old.

This makes their indetectability practically moot.
Theoretically it's still fun to think about. The only ways to detect them with current physics would be occlusion (low detection chance) and gravitational influence (low detection range).