Star finding help???

Question

In a star figure one star shows a parallax shift in the scale of the picture is 1mm=0.01''
I measured the shift to be 2mm...and from there I'm stuck can someone please help find what this star might be?

what does the amount of motion of the star= mm
Total parallax= ''
Stellar= ''
Distance= pc
= LY

Answer 1

If 1mm on the picture represents 0.01 arc seconds (0.01") then 2mm is 0.02". Distance in parsecs is one over parallax, in arc seconds. Since 1/0.02 is 50, it must be 50 parsecs away. Since a parsec is about 3.25 light years, it must be 50*3.25 or about 162 light years away.

Answer 2

Normally, the total shift is due to the movement of the Earth over its whole orbital diameter. However, distances are usually based on the "stellar parallax" based on the radius of our orbit.

Radius = half the diameter.

If you measured 2 mm, then total shift is 0.02", meaning the parallax angle is 0.01" (stellar parallax)

Distance in parsec is 1 / 0.01" = 100 parsecs = 326 light years (plus or minus 50, depending on the accuracy of your measurement). "Parsec" comes from "parallax second". If there were a star with a parallax of exactly 1", it would be located at 1 parsec (there are no stars that close to us).

Of the brightest stars, here are a few that are reported as having a stellar parallax of 0.01"

rho Persei at 320 l-y
Acrux at 320 l-y
Canopus at 310 l-y
Algenib at 300 l-y
Furud at 340 l-y
Aldnibah at 340 l-y

Answer 3

A star's distance d in parsecs is the reciprocal of its parallax p (or d = 1/p). One parsec = 3.262 light years.

I'll let you do the calculations.

HTH

Charles