Gives us the speed of stars
Doppler effect?
Since this is not my area of expertise, I searched Google under the key words "star speed measure astronomy" to get these possible sources:
http://www.associatedcontent.com/article/1839147/how_astronomers_measure_the_distance.html?cat=58
http://spiff.rit.edu/classes/phys240/lectures/expand/expand.html
http://en.wikipedia.org/wiki/Doppler_effect
http://answers.yahoo.com/question/index?qid=20080507061330AA7hTLH
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
I hope this helps a little more.
To find the speed of stars, we need to consider two different aspects: their proper motion and their radial velocity.
1. Proper motion:
Proper motion refers to the apparent motion of a star across the celestial sphere over time. It is measured in units of arcseconds per year (symbol: "/yr"). Proper motion can be obtained by comparing the star's position in the sky at different times. However, it is important to remember that proper motion gives us the angular velocity of a star relative to our line of sight, and not its true velocity through space.
2. Radial velocity:
Radial velocity represents the velocity of a star along our line of sight either towards or away from the observer. It is commonly measured using the Doppler shift of a star's spectral lines. When a star moves towards us, its spectral lines appear shifted towards the blue end of the spectrum (blueshift), indicating a higher frequency. Conversely, when a star moves away from us, the lines appear shifted towards the red end (redshift), indicating a lower frequency. The magnitude of this shift allows for the determination of the star's radial velocity.
By combining proper motion and radial velocity, astronomers can determine the star's actual motion through space. This three-dimensional velocity, known as space velocity, includes the component of motion in the plane of the sky (proper motion) and the motion directly towards or away from us (radial velocity).
It's worth noting that not all stars have measurable proper motion or radial velocity, especially distant or faint stars. However, for those stars with measurable values, they can range from a few kilometers per second (km/s) to hundreds of km/s, depending on their location within the galaxy and other factors.
To obtain the specific speed of a particular star, you would need to refer to astronomical databases, such as the SIMBAD database, which provides comprehensive information on known stars, including their proper motion, radial velocity, and space velocity. Alternatively, you can consult scientific literature or contact professional astronomers for specific data on individual stars.