Velocity determination through redshift


by Shyan
Tags: determination, redshift, velocity
Shyan
Shyan is offline
#1
Mar5-12, 07:44 AM
Shyan's Avatar
P: 734
As you know,astronomers calculate the velocity of distant stars by measuring their light's redshift.This suggests that they have a way to know each star's light's wavelength in a different way from observing its light.What is that way?
thanks
Phys.Org News Partner Astronomy news on Phys.org
Unique pair of supermassive black holes in an ordinary galaxy discovered
Red stars and big bulges: How black holes shape galaxies
Image: X-raying the cosmos
Janus
Janus is offline
#2
Mar5-12, 10:34 AM
Emeritus
Sci Advisor
PF Gold
Janus's Avatar
P: 2,352
They measure the shift in the star's spectrum. Each element produces a unique "fingerprint" as a pattern of lines in the spectrum. By looking at the position of these lines in the star's spectrum they can tell if they have been shifted from their normal position, this tells them the amount of red shift.

For Instance, if they find the pattern of lines associated with hydrogen closer to the red end of the spectrum than it should be, this tells then that the light has been red shifted. How far it has moved tells them by how much it has been red shifted.
Drakkith
Drakkith is offline
#3
Mar5-12, 05:33 PM
PF Gold
Drakkith's Avatar
P: 11,055
See here: http://en.wikipedia.org/wiki/Astronomical_spectroscopy


Register to reply

Related Discussions
velocity and redshift Special & General Relativity 11
Help with velocity/redshift/distance law Cosmology 2
Gravitational redshift and phase velocity Special & General Relativity 0
Graphical Velocity Determination Introductory Physics Homework 3
Simple Determination of Initial Velocity of a Pojectile Introductory Physics Homework 2