A few astronomy questions?

M

Meagan K

New member
I had tons of astronomy homework... and I got most of it done, but I can't figure out these problems... can you help me?

1) If a star has a parallax of 0.050 second of arc, what is it's distance in parsecs? In light-years? In AU?

2) If a star has a parallax of 0.016 second of arc, and an apparent magnitude of 6, how far away is it, and what is it's absolute magnitude?

3) If a main-sequence star has a luminosity of 400 L what is it's spectral type? (H-R diagram)

4) If a star has an apparent magnitude equal to it's absolute magnitude, how far away is it in parsecs? In light-years?

So if you guys could help me figure out how to solve these... that would be much appreciated. Thanks.
 
1) parallax of 0.050 second of arc
distance = 1/parallax angle = 1/0.05 = 20 parsecs
1 parcec = 3.26 light years
light year distance = light years*parsecs = 65.2
1 Parsec = 206264.806 AU
distance = 206264.806*20 = 4125296.12

2) star has a parallax of 0.016 second of arc
1/0.016 = 62.5 parsecs
Absolute Magnitude of 2

3) Spectral Type A

4) 10 parsecs
32.6 light years
 
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