Two stars have the exact same luminosity, but star Y is four times dimmer looking that star X. This means that????   1) star Y is four times as far away as star X   2) star Y is 16 times as far away as star X   3) star Y is half as far away as star X   4) star Y is twice as far away as star X   5) we can't figure out the relative distance of the two stars from the information given

1. Sirius A has an apparent magnitude of 4.72, determine its luminosity.

Barnard's Star is the 2nd closest star to Sol (~ 6 light years). It is moving toward the Earth with a speed of 110 km/s. Calculate the blue shift of light from Barnard's star, defined by AX/X. OA: OB: OC: OD: OE: -3.668x10-4 -4.586x10-4 -5.732x10-4 -7.165x10-4 OF: OG: -8.956x10-4 -1.120x10-3 -1.399x10-3 OH: -1.749x10-3

The three most prominent spectral lines of hydrogen are H-α at 656 nm, H-β at 486 nm, and H-γ 434 nm. If we observe an object with H-α at a wavelength of 700 nm, what wavelength will we observe H-β and H-γ? Is the object moving toward or away from us, and how do you know? Suppose we observe another object with H-α at 585 nm. Is this object moving toward or away from us? Is it moving slower or faster than the first object?