Does the Nemesis star exist?

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In summary, the Nemesis star is a concept that originated in the 1980s but is now considered obsolete by scientists. It was thought to be a possible companion star to the Sun, but it is believed to have left the Solar System more than 4 billion years ago. Due to the nature of stellar nurseries and open star clusters, it is possible that the Sun had a companion star that was lost shortly after formation. However, it is no longer considered a possibility by scientists.
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Nemesis star
Does the Nemesis star really exist? I don't think it does. If the Sun had a companion star it should have been detected by now. Stars don't go hidden.
 
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  • #2
It exists only as a concept, in our imagination.
 
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I'm sure you started with a web/Wikipedia search. What did you learn and what do you still need help understanding?
 
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If it does exist, one would have to ask how it has evaded our efforts to detect it. It is either very, very dim, which would mean it's probably NOT a star, its very far away, which would mean its NOT a companion of our Sun, is blocked by something like dust, which would obscure background stars and allow us to see this dust cloud (plus we can see through with infrared telescopes), or has somehow just hasn't been seen, which would mean that it would have to be somewhere in the sky where our astrometric telescopes and space probes (the ones that measure stellar distances) aren't looking.
 
  • #5
The nice rhing about the Wikipedia article is that it discusses what is and is not excluded., A star almost certainly. A big, cold planet*, not so much.

* Technically, under the de-planetification-of-Pluto ruling, this would not be a planet, since it has not cleared its neighborhood. It would be a "dwarf planet", even though it could be bigger than Jupiter.
 
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I just had a look at the Wikipedia article on Nemesis. It says that in 2017 that some scientist said that thought that the Sun may have had a companion star in the past, but it left the Solar System more than 4 billion years ago. This is a possibility. The reason why we would not be able to detect the historical companion star is because it is no longer a companion star, but got separated.

The Nemesis hypothesis originated in the 1980s and it was considered a serious possibility back then, however nowadays it is considered obsolete. Scientists today don't believe Nemesis to be a possibility.
 
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Jupiter60 said:
I just had a look at the Wikipedia article on Nemesis. It says that in 2017 that some scientist said that thought that the Sun may have had a companion star in the past, but it left the Solar System more than 4 billion years ago. This is a possibility. The reason why we would not be able to detect the historical companion star is because it is no longer a companion star, but got separated.
Indeed. Stellar nurseries often form dozens, hundreds, or thousands of stars in a confined area. It would be no surprise if the Sun had a close companion that was lost shortly after formation. Open star clusters, which is where the Sun likely formed, tend to 'disintegrate' over time.
 
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