If a star is found by spectroscopic observations to be about 500 parsecs distant, its parallax is:
A).2".
B).5".
C).02".
D).002".
E).005".

Question

Quizplus · Accepted Answer

The parallax angle is inversely proportional to the distance of the star. As the star is found to be about 500 parsecs distant, the parallax angle would be very small, leading to a higher value of distance modulus. The parallax would be around 1/500 or 0.002 arcsec, which is provided in option D. If a star is observed to be about 500 parsecs distant, its parallax would be very small, in the order of milliarcseconds. The only option that falls in this range is D, which represents a parallax of 0.002 arcseconds.

If a Star Is Found by Spectroscopic Observations to Be