Which of the following types of galaxies has experienced no significant star formation during the last 10 billion years |
Elliptical |
As we progress in the Hubble classification sequence of spiral galaxies from type Sa to Sb to Sc, how do the physical characteristics change |
The central bulges become smaller, while the spiral arms become less tightly wound |
Which of the following statements describes the orbits of stars within most elliptical galaxies |
They have random orbits in three dimensions |
Which type of galaxy exhibits the largest range of sizes and masses |
elliptical |
The Tully-Fisher relation uses the close correlation between the rotational speed of a spiral galaxy and its luminosity as a distance indicator. Why does this correlation exist |
The greater the mass of a galaxy, the faster it spins, and the more mass there is to give off light |
Why do errors and uncertainties in distance measurements get bigger the farther out we measure |
The techniques used to measure far distances are calibrated by using more local measurements; therefore, any errors accumulate |
Which of these standard candles has been used to determine distances to the most distant galaxies |
Type I supernovae |
What is the criterion for a group of galaxies to be considered a cluster |
Galaxies in a cluster are bound together by their mutual gravitational pull |
According to Hubble's law, as the distance to galaxies ________, the ________ increases |
increases; apparent recessional velocity |
Which of the following is NOT an implication of Hubble's law |
The Milky Way Galaxy is at the center of the Universe |
Active galaxies give off more energy than "normal" galaxies in what part of the electromagnetic spectrum |
All of the above |
What characteristic of some radio lobe galaxies suggests that their energy emission changes over time |
They display "blobs" of material along their lengths that indicate this material was ejected in bursts |
What is observed that connects radio emissions in the galactic nucleus with the emissions in the halo or radio lobes |
There is a jet of matter coming out of the nucleus, which often points toward the lobes |
How does the energy output from active galactic nuclei differ from the energy output from normal galaxies |
The emission of active galactic nuclei is nonstellar, whereas the emission of a normal galaxy is stellar |
What is the best explanation of the differences between a lobe radio galaxy and a core-dominated radio galaxy |
There is no real difference. When we look at core-dominated radio galaxies, we are looking at the galaxy through one of its lobes and along one of the jets |
Except for the nucleus, what does a Seyfert galaxy look like |
a spiral galaxy |
Early attempts to explain the spectra of quasars were unsuccessful because the spectra were which of the following |
redshifted by a larger amount than expected |
The fact that the energy output of active galactic nuclei can vary significantly over a short time indicates that the central object emitting the energy is which of the following |
much less than a parsec across |
Which of the following is NOT a characteristic of an active galaxy |
a regular, rapid pattern of radio frequency and optical emission peaks ranging from milliseconds to seconds in repetition rate |
The large amount of synchrotron radiation coming from an active galaxy indicates the presence of what in the active galaxy |
A powerful magnetic field |
Using the method of standard candles, we can, in principle, find the distance to a campfire if we know |
the number of logs used |
If the light from a galaxy fluctuates in brightness very rapidly, the region producing the radiation must be |
very small |
Active galaxies are very luminous because they |
contain black holes in their cores |
Quasar spectra |
are strongly redshifted |
According to Figure 15.18 (Galaxy Energy Spectra) in the textbook, active galaxies |
emit large amounts of energy at all wavelengths |
Most galaxies are spirals like the Milky Way |
F |
Most elliptical galaxies contain only young stars |
F |
Type I supernovae can be used to determine distances to galaxies |
T |
Most galaxies are receding from the Milky Way Galaxy |
T |
Within 30 Mpc of the Sun, there are about |
few thousand galaxies |
Hubble's law states that |
the greater the distance to a galaxy, the greater is the galaxy's redshift |
Irregular galaxies, although small, have lots of star formation taking place in them |
T |
Hubble's law can be used to determine distances to the farthest objects in the universe |
T |
Active galaxies can emit thousands of times more energy than our own Galaxy |
T |
If the galaxy in Figure 15.10 (Galaxy Rotation) in the textbook were smaller and spinning more slowly, then the igure should be redrawn to show |
a narrower combined line |