Question

Which of the following could be expressed as seconds of arc per year?

A. Radial velocity

B. Proper motion

C. Tangential velocity

D. Space velocity

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The proper motion of a star is

A. its tangential speed in km/s (measured in a direction perpendicular to the line of sight from the Earth to the star).

B. its radial speed in km/s (measured along the line of sight from the Earth to the star).

C. the diameter of the circle through which the star appears to move in the sky each year due to the motion of the Earth.

D. the angle through which the star moves across our sky per year.

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How can we tell that there is a binary system of stars even if we cant resolve both stars in a telescope?

A. The spectral class will vary with time in such a way to show two stars.

B. The luminosity class of the star will vary between giant and dwarf classifications.

C. Two sets of spectral lines will Doppler-shift red and blue opposite each other as time goes on.

D. The larger star will be stationary, but the smaller star will show a proper motion which will appear as a continuous Doppler shift.

E. The pair of stars’ luminosities will vary with time as they interact, and exchange matter.

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The spectra of spectroscopic binaries changes regularly due to

A. changes in the temperatures of the stars as they revolve.

B. changes in the size of the stars as they revolve.

C. changes in the absolute magnitudes of the stars as they revolve.

D. the Doppler effect.

E. [A, B, and C.]

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Of the following, which is the more fundamental quantity?

A. Absolute magnitude

B. Apparent magnitude

C. [They are equally fundamental.]

D. [No general statement can be made.]

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A star with an apparent magnitude of 3 emits ______ times as much energy as a star with an apparent magnitude of 5.

A. 0.6

B. 2

C. 2.5

D. 6.25

E. [The answer cannot be determined from the information given.]

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A star with an absolute magnitude of 3 emits_________ times as much energy as a star with an absolute magnitude of 5.

A. 0.6

B. 2

C. 2.5

D. 6.25

E. [The answer cannot be determined from the information given.]

Answer 1