Astro test four practice B

A star with a distance modulus of zero is at a distance of a. 10 parsecs. b. 1000 parsecs. c. 1 parsec. d. 10,000 parsecs. e. 100 parsecs.

A

Barnards star is a near neighbor of the Sun whose properties we know quite well. It is a type M4V with absolute magnitude 13.22. Suppose that another star of spectral type M4V is observed to have apparent magnitude 8.22. How far away is it? a. 1 parsec. b. 5 parsecs. c. 100 parsecs. d. 10 parsecs. e. 1000 parsecs.

A

In a Hertzsprung-Russell diagram,white dwarf stars such as Sirius B are a. at the lower left. b. at the upper right. c. at the upper left. d. at the lower right.

A

In the Hertzsprung-Russell Diagram, a main sequence star would not be found a. in the upper right or lower left. b. in the center. c. in the lower right or upper left.

A

Nuclear fusion requires high temperatures because nuclei a. repel each other. b. are extremely strong. c. have hard shells. d. have a lot of inertia.

A

Suppose that the color and behavior of a star identify it as a type that we know has absolute magnitude ñ3. If the stars apparent magnitude is found to be 7, how far away is it? a. 1000 parsecs. b. 50 parsecs. c. 5 parsecs. d. 10 parsecs. e. 100 parsecs.

A

The diffraction limit of a telescope refers to the effect of a. the wavelength of light. b. chromatic aberration. c. atmospheric turbulence. d. errors in the lens shape. e. its light collection area.

A

The first red giant stage of a one solar mass stars life usually ends with a. an explosion in the helium core. b. blowing out the hydrogen burning shell. c. a quiet transition to helium burning d. a core collapse. e. a complete shutdown of all nuclear reactions.

A

The position of a protostar on an HR diagram changes because a. the size and temperature of the protostar change. b. the protostar moves. c. the mass of the protostar changes. d. the protostar gets older.

A

When a white dwarf star collects matter from a neighboring star, fusion reactions on the surface of the white dwarf cause a. novas. b. a supernova. c. re-expansion to a red giant. d. a planetary nebula. e. a helium flash.

A

Which of these answers describes the fundamental assumption that is behind all of the methods that astronomers refer to as the "distance ladder?" a. Distant objects are similar to nearby objects. b. It is possible to calculate the absolute magnitudes of nearby objects. c. It is possible to measure the apparent magnitudes of distant objects. d. Nearby objects show close relationships between absolute magnitude and spectral type.

A

A mirror that is shaped like a shallow bowl sitting on the table with its open end facing up will focus light that comes a. vertically upward from below. b. vertically down from above. c. horizontally from the side.

B

A star that is approximately the size of the Earth is probably a a. horizontal branch star. b. white dwarf star. c. brown dwarf star. d. main sequence star. e. red giant star.

B

Cruising far from the Sun, we notice that the Sunís apparent brightness has dimmed to 10 watts per square meter. We know that the apparent brightness at a distance of 1au is 1000 watts per square meter. How far from the Sun are we? a. 1 au b. 10 au c. 100 au d. 1000 au

B

For stars on the main-sequence, stars with decreasing mass have a. decreasing surface temperature and increasing absolute brightness. b. decreasing surface temperature and absolute brightness. c. increasing surface temperature and decreasing absolute brightness. d. increasing surface temperature and absolute brightness.

B

In a particular binary star system, we are only able to determine a minimum mass for each star and cannot determine the angle between our line of sight and the plane of the stars orbits. This system is most likely a. an eclipsing spectroscopic binary system. b. a spectroscopic binary system. c. a visual binary system.

B

Stars with more than 15 times the mass of our Sun usually evolve o§ the main sequence along a path in the HR diagram that a. is mostly vertical. b. is mostly horizontal. c. starts out vertical and then goes almost horizontal. d. starts out horizontal and then goes almost vertical.

B

The formation of a new white dwarf is usually accompanied by a a. dust cloud. b. planetary nebula. c. nova. d. helium flash. e. supernova explosion.

B

The mass of a carbon atom is 12.00amu while the mass of a helium-4 atom is 4.003amu. If a gamma ray photon splits a carbon atom into three Helium atoms, how much energy is converted into mass? a. 0.006amu b. 0.009amu c. 0.004amu d. 0.002amu e. 0.012amu

B

The violet lines in the Hydrogen spectrum are normally seen with wavelengths 410 nm and 434 nm. In the light of a star that is moving toward us, we might expect to see those lines at wavelengths of a. 410 nm and 434 nm b. 400 nm and 424 nm c. 415 nm and 439 nm

B

When the core of a star collapses while inside the star, the result is a a. ordinary nova. b. type II supernova. c. gamma-ray burst. d. type Ia supernova.

B

When the hydrogen fuel runs out at the center of a main sequence star, the star a. stops burning and becomes a brown dwarf. b. swells up and becomes a red giant. c. begins to collapse to a white dwarf star. d. explodes as a supernova. e. continues as a main sequence star.

B

A black hole that has formed from the collapse of a star is expected to be a. 100 times the size of a neutron star. b. less than 1/10 the size of a neutron star. c. similar in size to a neutron star.

C

A star whose full spectral type is K2V is a. a red giant star. b. a bright blue supergiant star. c. a red main sequence star. d. a red subgiant star. e. a red supergiant star.

C

A star with an apparent magnitude of 8:4 and an absolute magnitude of 1:0 would appear in our sky as a star a. that is barely visible to the naked eye. b. of dazzling brightness. c. that is visible only with a telescope. d. of average naked-eye brightness.

C

High protostellar winds of ejected gas occur when the protostar is in the a. Tau Ceti phase. b. photosphere formation phase. c. Tau Tauri phase. d. nuclear ignition phase. e. main sequence phase.

C

The average energy of motion of an atom or molecule in a gas is called its a. entropy. b. density. c. temperature. d. frequency.

C

The object Gliese 229B glows in the infrared but is much cooler and dimmer than a class M star and shows traces of lithium that a normal star would quickly burn up in the nuclear reaction that occurs in its core. This object is most likely a. a planet. b. a yellow dwarf. c. a brown dwarf. d. a white dwarf. e. a class M object.

C

The origin of the energy that is released in a supernova explosion is a. nuclear energy stored in the star. b. matter-antimatter annihilation. c. gravitational energy from the core collapse. d. rotational energy in the core.

C

The red subgiant stage of a star is best described by a. dropping temperature and increasing brightness. b. constant temperature and brightness. c. dropping temperature and constant brightness. d. increasing temperature and increasing brightness. e. increasing temperature and decreasing brightness.

C

The star 36-Ophiuchus is six parsecs from our Sun. The light from this star in the 'serpent holder' constellation has been traveling for approximately a. 0:55 years. b. 12 years. c. 20 years. d. 1:8 years. e. 6 years.

C

The star Wemadeit shows a stellar parallax angle of 0.2 seconds of arc while the star Waytoofar shows a stellar parallax angle of 0.3 seconds of arc. From this, you can conclude that a. Both stars are at the same distance from our Sun. b. Wemadeit is moving faster than Waytoofar. c. Waytoofar is closer to our Sun than Wemadeit. d. Wemadeit is closer to our Sun than Waytoofar. e. Waytoofar is moving faster than Wemadeit.

C

The velocity of a wave is defined to be a. the distance from one crest to the next. b. the time taken for a crest to pass. c. the distance traveled by a crest divided by the time taken. d. the number of crests that pass divided by the time taken. e. the number of crests that pass multiplied by the time taken.

C

The velocity of sound waves is roughly the same for all wavelengths. Suppose that a sound wave has a wavelength of one meter and a frequency of 1000Hz. The wavelength of a 250Hz sound wave would then be a. 250 m. b. 1/4 m. c. 4 m. d. 1 m. e. 1000 m.

C

Think of the front of a telescope as the end that light enters. A telescope with Newtonian Focus has the eyepiece a. sticking out the side near the back. b. inside the telescope barrel. c. sticking out the side near the front. d. at the back of the telescope. e. off to one side in a position that stays fixed when the telescope moves.

C

Which of the following magnitudes corresponds to the brightest star? a. +2:1: b. +5:6: c. 1:5: d. +3:4: e. +1:2

C

Which of the following particles has the smallest mass? a. proton. b. neutron. c. electron. d. deuteron.

C

A star is seen to move by 0:8 seconds of arc between March 1, 1999 and September 1, 1999 and then back to its starting point on March 1, 2000. What is the parallax angle for this star? a. 0:2 seconds of arc. b. 0:3 seconds of arc. c. 0:8 seconds of arc. d. 0:4 seconds of arc. e. 0:1 seconds of arc.

D

Adaptive optics is used to correct telescopes for a. the diffraction limit. b. spherical aberration. c. poor light collection ability. d. atmospheric turbulence. e. chromatic aberration.

D

Stars that are much more massive than our Sun a. form faster but burn slower. b. form more slowly and burn slower. c. form more slowly but burn out faster. d. form faster and burn out faster.

D

Which of the following spectral types corresponds to the star with the highest surface temperature? a. G5 b. G0 c. F5 d. F0

D

A star at a distance of 10,000pc should have an apparent brightness equal to its absolute brightness multiplied by a. 10^-4: b. 10^-2: c. 10^-3: d. 10^-5: e. 10^-6:

E

A star whose apparent brightness is 104 times that of a sixth magnitude star would have magnitude a. 6. b. 1. c. 11. d. 21. e. 16.

E

Because mirrors only use one surface, they have a big advantage over lenses: They can be a. thicker and stronger. b. made out of metal. c. made more accurately. d. filled with more holes. e. thinner and larger in diameter.

E

Ham radio operators sometimes operate receivers for the 2 meter wavelength. The 2 meters refers to the a. size of the near-field zone of the receiver. b. length of the required radio antenna. c. maximum amplitude of the radio waves. d. frequency of the radio waves. e. distance from one maximum of the radio waves to the next.

E

In order to use spectroscopic parallax to find the distance to a star, you need to know a. only the spectral type and luminosity class (B2V for example). b. the spectral type (O, B, A, etc.) and the absolute magnitude. c. the spectral type and luminosity class (B2V for example) and the absolute magnitude. d. only the spectral type (O, B, A, etc.) e. the spectral type and luminosity class (B2V for example) and the apparent magnitude.

E

Neutron stars are often observed as a. novas. b. quasars. c. Tau Tauri stars. d. asteroids. e. pulsars.

E

Stellar Parallax is caused by a. the motion of our Sun relative to its neighbors. b. the finite speed of light. c. turbulence in the Earths atmosphere. d. the actual motion of stars relative to their neighbors. e. the motion of the Earth around the Sun.

E

We see what appears to be a single star. However, when the light from the star is put through a spectrometer, we see two distinct spectra, shifting back and forth. The star is actually a. a single-line spectroscopic binary system. b. an astronometric binary system. c. just a single star with a weird spectrum. d. a visual binary system. e. a double-line spectroscopic binary system.

E