Stellar Parallax

Stellar Parallax

Name:______Section:__Online___ Date: ______

Procedure

1.  Using a ruler and Figure 1, draw a line from the Earth through the center of Star A and extend it through the distant stars at the top of the page. This is an Earth observer’s line of sight for this date.

2.  Now we can locate the position of Star A in the telescope field of view (Figure 2) relative to the distant stars. Make a small “X” at that location and label it “A, Jan. 1”.

3.  To see the parallax displacement the observer would wait 6 months and repeat the observation on July 1. First, you need to accurately locate the Earth for
July 1 by making a small dot on the Earth’s orbit (label the point July 1).

4.  Draw a line beginning from the July 1 position of the Earth, through Star A and again extent the line through the distant stars.

5.  Now locate this position for Star A in the telescope field of view. Make a small “X” at that location and label it “A, Jul. 1”.

6.  Lightly draw a line connecting the January 1 and the July 1 star positions and label this parallax displacement “pA”.

7.  Repeat the procedure but this time for Star B.

Questions

1.  Is a parsec a unit of distance, an angular unit, or a unit of time?

2.  For a star with a parallax of 0.167 arc seconds (p = 0.167 arcsec), what is its distance from us in light-years?

3.  Consider two stars that are different distances from the Earth. Star 1 has a parallax 1/5 as large as Star 2. Which star is farther away? How much farther?

4.  Find the distance in light-years to the star Wolf 359. The necessary information to make this calculation can be found in the telescopic observations shown below. (Hint: Use a ruler to measure the parallax displacement in centimeters, then convert it to arc seconds and don’t forget, parallax is 1/2 the measured displacement.) Show your work!

5. 

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