Question

Which of the following is used to determine if a star is moving closer to Earth?

Absolute magnitude

Brightness

Doppler shift

Parallax

Answer 1

it is parallax. this is how it works: Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. Nearby objects have a larger parallax than more distant objects when observed from different positions, so parallax can be used to determine distances.

Answer 2

The Doppler effect concerns objects in motion - most notably sirens on police cars and ambulances change pitch as they go past. The same thing happens for light from stars that are approaching or receding - look up red shift and blue shift and you'll get a better explanation. As for parallax, I think this might be useful for determining the distance of a star, but I'm a Biologist rather than an astrophysicist!

Answer 3

I think you are correct, ebaxter01.

I found this off the Wiki page.
"The Doppler effect for electromagnetic waves such as light is of great use in astronomy and results in either a so-called red shift or blue shift. It has been used to measure the speed at which stars and galaxies are approaching or receding from us, that is, the radial velocity. This is used to detect if an apparently single star is, in reality, a close binary and even to measure the rotational speed of stars and galaxies"

Answer 4

so the answer is?

Answer 5

You should be able to figure it out off of what ebax mentioned.