ASTR 113 Test 3

The diagram below illustrates the velocities of galaxies for a model of expanding universe with H0= 50 km/s/Mpc as seen from the Milky Way. What would be the velocity of Galaxy #4 with respect to Galaxy #2? 1000 km/s 750 km/s 500 km/s 250 km/s

500 km/s

Which of these plots best illustrates the star formation rate for an ellipitical galaxy?

A which is a line going up rapidly then down rapidly and platueing

Which of these graphs correctly reflects the relationship between recessional velocity Vr and Distance D for galaxies as expressed by Hubble's Law?

B which is a graph with a perfect ascending line

Quasars vs. pulsars Match different properties with the appropriate objects (Note: the same option can be used more than once).

Both involves compact, Quasars emit large amounts of high energy, quasars luminosity is larger, and pulsars emission varies on regular periods

The pictures below show three possible geometries of the universe, which depend on the density of matter and energy of the whole universe with respect to a critical value. Order them from the lowest to the highest density.

Curvy C, Flat B, Round A

What property determine if the universe will expand forever? A. the amount of normal matter in the universe B. the amount of dark matter in the universe C. the amount of dark energy in the universe D. A and B E. A, B, and C

E. A, B, and C

A graduate student needs to measure the mass of a spiral galaxy she is studying. Which of the following observations would be important for her to make? She should compare the color of the galaxy to other galaxies of the same type. She should construct an H-R diagram for an open cluster in the galaxy's disk. She should measure gamma ray emission from the galaxy. She should measure the speed of stars or gas near the outer regions of the galaxy.

She should measure the speed of stars or gas near the outer regions of the galaxy

Among irregular galaxies what makes the Large and Small Magellanic Clouds especially useful for astronomers? They contain only very old stars. They have a regular but extremely complicated shape. They are among the biggest irregular galaxies ever found. They are (for galaxies) very close to us, so they are easy to stud

They are (for galaxies) very close to us, so they are easy to study.

Put in chronological order starting from the beginning the following events in the history of the universe. Big Bang unification of fundamental forces annihilation and pair production primordial fusion of hydrogen into helium nuclei formation of neutral atoms formation of first stars formation of first neutron stars

They're in order

A spiral galaxy consists of both a disk and spheroidal component neither a disk or spheroidal component only a disk disk component only a spheroidal component

both a disk and spheroidal component

Dark matter in clusters of galaxies (like the one shown below) is detected ... by observing gravitational lensing of galaxies located in front of the cluster. by measuring the rotation velocity of stars in the galaxy outskirts. by observing gravitational lensing of galaxies located behind the cluster. by measuring the velocities of galaxies by observing the radio emission produced by the intracluster gas.

by observing gravitational lensing of galaxies located behind the cluster.

The galaxy at the center of a well-populated cluster of galaxies is most likely a(n) any galaxy without any preference for a specific morphological type spiral galaxy elliptical galaxy irregular galaxy

elliptical galaxy

A protogalactic cloud that forms an elliptical galaxy would likely have low density and large angular momentum high density and small angular momentum high density and large angular momentum low density and small angular momentum

high density and small angular momentum

The Hubble's diagram below illustrates the uncertainties for a few galaxies. The uncertainties on the galaxy distances are due to difficulties encountered applying different techniques of distance determination. Based on the plot we can conclude that these uncertainties there is not enough information to derive a conclusion increase with distance decrease with distance do not change with distance

increase with distance

According to the Cosmological Principle, the universe is isotropic and homogeneous consists only of galaxies that are exactly like the Milky Way cannot be understood by the use of scientific observations alone has no beginning and no end has all the galaxies arranged in groups about the size of our Local Group

is isotropic and homogeneous

Galaxy collisions were ... in the early universe than they are today more common just as common less common there were no collisions in the early universe

more common

An irregular galaxy consists of both a disk and spheroidal component only a spheroidal component only a disk disk component neither a disk or spheroidal component

neither a disk or spheroidal component

Extragalactic astronomy is often compared to a time machine because looking in the appropriate direction in the sky, we can see the future. observing different galaxies at different distances is equivalent to looking at different cosmic times, which allows one to study the evolution of galaxies. we can follow the evolution of an individual galaxy. Since we know that the life duration of stars is inversely proportional to their mass (i.e., high-mass stars live a shorter life), and since galaxies have very large masses, we can follow the evolution of individual galaxies on human timescales. actually it is more similar to a washing machine, since everything rotates (ga

observing different galaxies at different distances is equivalent to looking at different cosmic times, which allows one to study the evolution of galaxies.

Today we know that what all quasars have in common is that they appear to be small sources of energy with strong radio emission showing regular pulses tremendous proper motion (apparent motion across the sky) no lines in the spectrum at all redshifts that indicate they are far away gravitational lenses clearly visible around them

redshifts that indicate they are far away

Spiral galaxies appear white because they contain stars of all ages and colors mostly old red stars mostly young red stars mostly old blue stars mostly young blue stars

stars of all ages and colors

The Hubble tuning fork is useful for

summarizing galaxy classification by morphology

The Hubble tuning fork is useful for summarizing galaxy classification by morphology describing galaxies based on their size and metallicity illustrating the evolutionary paths of galaxies organizing galaxies by size and age

summarizing galaxy classification by morphology

Scientists speculate that the properties (laws) of te universe must be the way they are because if they were significantly different, we would not be here to think about them. This idea is called the Hubble law the anthropic principle the inflationary self-image hypothesis the narcissus conjecture the cosmological principle

the anthropic principle

When two galaxies collide why don't their stars typically collide? the supermassive black hole at the center of the galaxies swallows the stars stars actually collide frequently during galaxy mergers the distance between stars is very large compared to their size stars don't interact gravitationally with each other

the distance between stars is very large compared to their size

This image shows the expected and observed rotation curves for a galaxy. The fact that the observed speed of stars is much faster than expect near the far edge of the galaxy is an indicator that a second galaxy has recently merged with the galaxy in the image the mass of stars in the galaxy is much greater than expected the galaxy includes mysterious "dark matter" the galaxy is in the process of flying apart

the galaxy includes mysterious "dark matter"

With enormous effort, a team of astronomers manages to collect enough light from a galaxy far, far away to produce a spectrum. That spectrum has lines from the elements carbon, silicon, and sulfur. This tells the team that the galaxy must be a massive elliptical galaxy the galaxy must have had an entire generation of stars that was born, lived, and died the galaxy must be closer to us than 1 billion light years the galaxy must contain a quasar what they are seeing is not a galaxy at all, but the remnant of one supernova

the galaxy must have had an entire generation of stars that was born, lived, and died

Because of the expansion of the universe, which of these objects are moving apart? two planets in a stellar system two stars in a galaxy two galaxies in a clusters two widely separated galaxies all of the above

two widely separated galaxies

Which of the following objects i s considered useful to astronomers as a "standard bulb" (also called "standard candle") for determining distances.? the size of the largest open cluster in a galaxy type Ia supernovae the brightness of the central bulge in a galaxy K-type stars

type Ia supernovae

Compared to current nearby galaxies, early galaxies ... had already their final shape were redder in color were more numerous were less numerous were less likely to interact were bluer in color

were more numerous were bluer in color