Why would a star show little parallax?

Question

thanks for helping

Answer 1

The "nearby" stars do show parallax when a photo is taken 6 months apart--- as the Earth orbits the sun.

as distances increase -- the star cannot be seen to move in photos taken even using Earth's orbit as a baseline.

Answer 2

We can tell the distance of stars using their parallax (or apparent change in position) as the Earth moves in its orbit.  Stars that are very close have the highest parallax and stars that are far away have very little.  Alpha Centauri, the sun-like star nearest to our solar system, has a distance of 4.3 years and a parallax of 0.75", which is the highest of any object outside our solar system.  The farthest away stars that we can parallax using the Earth's movements are about 1,600 light years away.  So a star with little parallax must be approaching this limit on the distance.

Just to give you some intuition on how parallax works, do this simple experiment.  We can tell the distance of objects here on Earth from us using the parallax between our two eyes (your brain does this for you automatically, so you don't even notice, but this is how you have depth perception.)  Hold your finger about 6 inches from your face and look at it with only your left eye open.  Now look at it with only your right eye open.  Did you notice an apparent movement in your finger?  That is parallax.  Try the same with an object that is a few feet away. It appears to move as well, but not as much because it is farther away.  Now try it with something that is quite far away by looking out the window and gazing off into the distance.  You will probably not see any apparent movement.  

Answer 3

The Earth is about 93 million miles from the Sun.  Twice that is 186 million miles from the Sun.  It sounds like alot.  Proxima Centauri is 24,942,475 million miles. away. So the angle isn't much.  Just 768.7 milliarc seconds.

Bright stars like Deneb are approximately 3000 light years away - one thousand times farther.  A star like this is bright because the the brightness range of stars goes from about 10,000 times dimmer than the Sun to 10,000 times brighter than the Sun.  So just because it's bright doesn't mean it's near by.