Astronomy Exam 2 Part 4

A. the universe is expanding.

B. the fabric of space is curved by the presence of mass.

C. all galaxies see themselves at the center of universal expansion.

D. light travels at a finite velocity and takes time to get to us.

E. the universe had a distinct beginning about 15 billion years ago.

A. the faster they vary, the more distant they are.

B. their luminosity can be determined from their period of variation.

C. they obey Hubble’s law.

D. they are the most common type of main-sequence star visible in galaxies.

E. they all lie in the same spot on the HR diagram.

A. luminosity

B. temperature

C. radius

D. rotation rate

E. density

A. the Doppler shifts of stars on each side of its center.

B. the relative motions of other galaxies inside them.

C. the length and curvature of their spiral arms.

D. the time it takes individual stars to orbit the center.

E. None of the above—galaxies don’t rotate.

A. some of the most distant galaxies coming toward her and some going away from her.

B. many more nearby quasars than we do.

C. our Galaxy approaching her.

D. the more-or-less same relation between redshift and distance that we see.

E. All of the above.

A. he observed that the nebula was rotating.

B. he used Cepheid variables to find it was a tremendous distance away.

C. he determined that the nebula was moving away from our Galaxy.

D. he counted that there were more than one billion stars in the nebula.

E. he detected dust and gas in the nebula.

A. red giants.

B. main-sequence stars.

C. planetary nebulae.

D. the Big Bang.

E. supernovae.

A. dark matter.

B. neutral hydrogen.

C. luminous stars.

D. ionized hydrogen.

E. black holes.

A. Mass that disappears into black holes.

B. Mass made of anti-matter whose effect cancels out the gravity of ordinary matter.

C. Mass that radiates strongly at X-ray wavelengths and is therefore invisible with ordinary light.

D. Mass deduced to be present from its gravitational effect but which emits no visible light or other detectable radiation

E. None of the above.

A. tells us that the universe is expanding.

B. permits us to measure the distances to distant galaxies and quasars.

C. implies that the universe had a beginning about 15 billion years ago.

D. says that more distant galaxies recede more rapidly than nearby ones.

E. all of the above.