Question

Star A and Star B have measured stellar parallax of 1.0 arc second and 0.75 arc second, respectively. Which star is closer? How do you know?

Answer 1

Star A is closer than Star B

Step-by-step explanation:

As we know that in parallax method of distance measurement the angle subtended by the star when it covers a distance of one Parsec arc length, it is known as parallax angle

Here we can say

`angle = (1 Parsec)/(distance)`

so we have

`distance = (1 Parsec)/(angle)`

so here we have

angle subtended by Star A = 1 arc sec

angle subtended by star B = 0.75 arc sec

now we have

distance for star A is given as

`d_a = (1 Parsec)/(1) = 1 Parsec`

distance of star B is given as

`d_b = (1 Parsec)/(0.75) = 1.33 Parsec`

So star A is closer than star B