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1) Find the distance of a star whose parallax is

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1) Find the distance of a star whose parallax is .02′′ in parsecs, kilometers, and light-years. 2. Two stars have parallaxes of .1′′ and .005′′, respectively. Which star is closer to us, and how much? If the stars are equally luminous, how much brighter will the nearer one appear than the farther one? 3. Star A has a parallax of .2′′ and star B has a parallax of .04′′. Star B appears 3 times as bright as star A. Which of the stars is more luminous, and by how much? 4. The radial velocity of a star is 5 km/sec and its tangential velocity is 12 km/sec. What is the space velocity of the star? 5. Why is it easier to detect proper motion than parallax? What else do you have to know besides its proper motion in order to find the tangential velocity of a star? 6. A star at a distance of 100 pc has a radial velocity of 25 km/sec. By what percentage does its distance from us change after a) 100 years, and b) 1 million years? (1 year=3×107sec.). 7. A star is 10 pc away. It is observed to have a proper motion of 10′′ per year. What is its velocity relative to the Sun, as measured perpendicular to the line of sight between us and the star? 8. A star is 20? above the horizon at its highest point on the celestial sphere on some night. A year later, it is 20? 10′′ above the horizon when it reaches this highest point. What is its proper motion? Where will it be (i.e. at what angle) after another 359 years? What will its proper motion be at that time? 9. Two stars have the same proper motion. Star A is 100 pc away, moving at a speed of 300 km/sec in the radial direction and 500 km/sec along its direction of motion. Star B is only 10 pc away. What is its velocity perpendicular to our line of sight? What can we say for sure about the radial velocity of star B?