Exam 3

galaxies that we see as they were 11 billion years ago or more, as compared to galaxies today, are generally:

a. bluer, and smaller

to predict whether a star will ultimately become a black hole, what is the key property of the star we should look at? a. mass b. surface temp c. color d. distance e. diameter

a. mass

why do astronomers think that they are fewer quasars today than there were billions of years ago?

a. quasars are seen when the supermassive black hole at the center of a galaxy has a lot of "food to eat" (stars and gas) and the amount of available food tends to decrease with time

the very strong sources of radio waves at the center of our galaxy is called a. sagittarius A b. cygnus x-1 c. the crab nebula d. milky way CC1 e. benford G1

a. sagittarius A

our milky way galaxy is what type of galaxy? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above

a. spiral

the type of galaxy that sometimes has a distinct bar of stars running across the central region is a. spiral b. elliptical c. dwarf elliptical d. irregular e. all of the above can have clear, distinct central bars

a. spiral

which of the following statements about our modern ideas of how spiral galaxies form and develop is true?

a. the central bulges of spiral galaxies formed first and their disks formed later

for galaxies that have super-massive black holes at their centers, how do astronomers find that the mass of the host galaxy and the mass of the black holes are related?

a. the more massive the galaxy, the more massive of the black hole are related?

which of the following objects is considered useful to astronomers as a "standard bulb" for determining distances? a. type IA supernove b. planets that resemble earth c. k-type stars d. the brightness of the bulge in a galaxy's center e. the size of the largest diameter open cluster in a galaxy

a. type IA supernove

after several decades of observation, astronomers have concluded that quasars are a. very powerful and compact sources of energy at the centers of distant galaxies b. projectiles shot out of our own galaxy and moving out into intergalactic space c. energetic collisions of comets in the oort cloud d. anti-matter stars in the halo of the milky way galaxy e. a completely baffling mystery with no hint of an answer

a. very powerful and compact sources of energy at the centers of distant galaxies

the ________ galaxy is the closest big galaxy to our milky way

andromeda

which type of galaxy is observed to contain mostly older stars? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above

b. elliptical

astronomers believe that the large elliptical galaxies formed

b. form the collision and merger of many smaller fragments

the scientist who made the first telescopic survey of the milky way and discovered that it is composed of huge number of individual stars was a. isaac newton b. galileo galilei c. edwin hubble d. harlow shapley e. jill tarter

b. galileo galilei

which of the following is not a characteristic of a spiral galaxy? a. most of its material is in the shape of a flattened disk b. it has quite a bit of gas and dust in it c. it has young stars and bright emission nebulae d. when we take spectra of its stars, they have far less of the heavier elements than the sun e. the bright stars in it can be seen organized into distinct spiral arms

b. it has quite a bit of gas and dust in it

how can supermassive black holes at the centers of galaxies help new stars to form in that galaxy?

b. new stars can form when the flow of particles from a black hole accretion disk or jet compresses the material some distance away from the black hole and starts the "clumping" that leads to the formation of stars

your weird cousin, who is really into astronomy, decides that the return address he uses on his letters is incomplete! to his city, state, and country, he begins to add;" north america, earth, solar system...": if he now wants to include the name of the galaxy's sprial-structure feature in which the earth is located, how should his address end? a. cygnus arm b. orion spur c. perseus arm d. sagittarius-carina arm e. mar arm

b. orion spur

When astronauts aboard the space shuttle in space let go of an orange, it just floats there. why is that? a. the ISS is so far from earth, the gravity there is essentially zero b. the ISS is falling around the earth, and in free fall, things feel no weight c. spacetime is so different aboard the ISS, that time stops, and nothing can fall d. the law of gravity only works on the earth, it doesn't work in space e. this is an unsolved problem in science, and so it is "fruitless" to worry about it

b. the ISS is falling around the earth, and in free fall, things feel no weight

what observation in astronomy, made after the discovery of quasars, was a big help to astronomers in figuring out what quasars really were? a. the understanding that most stars become white dwarfs when they die and white dwarfs are much smaller than main-sequence stars b. the discovery that the milky ways galaxy has a black hole at the center with enough mass for 4 millions suns c. the discovery that the galaxies mostly show a red shift d. the discovery of exoplanets (planets orbiting other stars) throughout the galaxy e. the discovery of herbig-halo objects around newly forming stars

b. the discovery that the milky ways galaxy has a black hole at the center with enough mass for 4 millions suns

if a very distant galaxy looks bluer overall to astronomers, from this they can conclude that:

b. the galaxy must have a lot of young stars and thus active star formation must still be going in it

once a black hole forms, the size of its event horizon is determined only by a. the size (diameter) of the star that collapsed into the black hole b. the mass inside the event horizon c. the time since the black hole formed d. the composition of the material that formed the black hole e. you can't fool me; every black hole has an event horizon of the same size

b. the mass inside the event horizon

the andromeda galaxy (our nearest spiral neighbor) has spectral lines that show a blue shift. from this we may conclude that: a. the universe is no longer expanding b. this particular nearby galaxy is moving towards us c. this galaxy has merged with the milky way and is now part if it d. this particular nearby galaxy is moving away from us e. this galaxy has an unusual of very bright and hot o-type stars in it

b. this particular nearby galaxy is moving towards us

An object whose gravity is so strong that the escape velocity from it exceeds the speed of the light called _________

blackhole

astronomers have concluded that growing supermassive black holes (which have millions of times the sun's mass or more) is pretty unlikely at our location in the milky way galaxy. where do they think is the most likely place in the milky way for such a supermassive black hole? a. at the outer edge of the galaxy's disk, where there is less pull from other stars b. where a neutron star has already formed c. at the center of the milky way galaxy, where matter if more crowded d. at the location astronomers call cygnus x-1 e. no place in our galaxy is likely for a really massive black hole

c. at the center of the milky way galaxy, where matter if more crowded

according to our current understanding, giant elliptical galaxies form:

c. by the merger (or swallowing) of a number of smaller galaxies in a cluster of galaxies

which of the following objects do many astronomers believe is a black hole? a. the nebula in Orion where new stars are seen to form (from dark dust clouds) b. the crab nebula c. cygnus x-1 d. the open cluster called the pleiades e. bayonne, new jersey

c. cygnus x-1

which type of galaxy is very difficult to see, but may be very common? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above

c. dwarf elliptical

If you are in a freely falling elevator near the top of a tall building, as the elevator falls your weight would be: a. the same as your usual weight b. a bit less than your usual weight c. equal to zero-you would be weightless d. a little more than your usual weight e. so great that you would be pressed to the floor and in great pain

c. equal to zero-you would be weightless

most spiral galaxies consist of: a. flat, rotating disk containing stars b. gas and dust c. gas, dust and bulge d. flat, rotating disk containing stars, gas, dust, and bulge

c. gas, dust and bulge

to map out how clusters of galaxies are distributed in the universe, astronomers needed to know where each cluster was in the sky and

c. how far away from us each cluster was

where would you look for the youngest stars in the milky way galaxy? a. in the halo b. where there is dark matter c. in the disk d. in the nuclear bulge e. you can't fool me; my chances of finding a very young star are the same, wherever in the galaxy I look

c. in the disk

the astronomer who first worked out the mathematical description of black hole event horizons was a. edwin hubble b. jocely bell c. karl schwarzschild d. s. chandraskehar e. frederick Pohl

c. karl schwarzschild

today, astronomers find compelling evidence that they energy source of the quasars and active galaxies is a. antimatter and matter colliding at the center of a galaxy b. chain reactions of supernova explosions c. matter falling toward a supermassive black hole at the center of a galaxy d. the left-over (and stored) energy of the big bang explosion e. you can't fool

c. matter falling toward a supermassive black hole at the center of a galaxy

how do astronomers now explain the fact that the energy emitting regions for quasars are so small? a. quasars are just optical illusions caused by gravitational lensing effects b. quasars are the result of 3 or 4 galaxies colliding: the collision squeezes the quasar c. quasars are the result of matter falling into a black hole; the event horizons of even supermassive black holes are extremely small on the cosmic scale d. quasars are caused by the actions of neutron stars and neutron stars have been squeezed so much that they are very, very small e. you can't fool me, there is no plausible explanation for the small sizes of quasar energy regions

c. quasars are the result of matter falling into a black hole; the event horizons of even supermassive black holes are extremely small on the cosmic scale

why do galaxies collide, while stars almost never do,

c. stars are much farther apart (compared to how big they are) than galaxies are

an astronomer discovers a massive galaxy which has 4 nuclei. what is a likely explanation for a galaxy having more than one nucleus?

c. the galaxy must have swallowed several smaller galaxies that were its neighbors

in the first direct detection of gravitational waves by LIGO 2015, the waves came from a. the collapse of a nearby star into a white dwarf b. a supernova explosion in a nearby galaxy c. the merger of two black holes d. the rapid motion of three hot Jupiter planets around a nearby star e. the dashed hopes of all the people in the US who want their government to work well for them

c. the merger of two black holes

edwin hubble developed a classification scheme for galaxies. by what characteristic did he classify galaxies? a. their brightness b. their overall color c. their shape d. their abundance of the element iron e. their doppler shift

c. their shape

by examining rich clusters of galaxies, such as the coma clusters, astronomers have discovered that spiral galaxies

d. are found mostly in the outer regions of such clusters, not in the middle

what method would astronomers use to find the distance to a galaxy so far away that individual stars are impossible to make (resolve)? a. parallax b. cepheid variables c. using the x-ray emission from the entire galaxy d. finding the redshift and using hubble's law e. the turnoff point of the main sequence on an H-R diagram

d. finding the redshift and using hubble's law

what method would astronomers use to find the distance to a remote quasar? a. parallax b. cepheid variables c. measuring the size of its dark matter halo d. finding the redshift and using hubble's law e. the turnoff point of the main sequence of H-R diagram

d. finding the redshift and using hubble's law

when quasars "shine" (in visible light and other kinds of radiation) with a lot of energy, where (what location) does this huge amount of energy come from? a. from the outer spiral arms of the galaxy in which the quasar is located b. from inside the event horizon of a supermassive black hole c. from supernova explosions (a whole bunch of them all at once) in the galaxy on which the quasar is located d. from an accretion disk around a supermassive black hole e. from a much more distant object to lie behind the quasar and fools us into thinking the quasar is shining

d. from an accretion disk around a supermassive black hole

if we want to see what galaxies looked like at a time close to the beginning of the universe, where should we look?

d. in a direction away from the plane of the milky way, where we can see very faint galaxies that are more than 10 billion light years away

what was especially noteworthy about the sagittarius dwarf galaxy when it was discovered among the small galaxies near the milky way? a. it was so large in mass, astronomers could not understand how the milky way wasn't flying toward it b. it had a supermassive black hole in the center much larger than the milky ways c. it was rotating so quickly that it could not hold together for very long d. it was on a collision course with the milky way and would be swallowed by it eventually e. it was made entirely of dark matter and so could not been seen on any photographs

d. it was on a collision course with the milky way and would be swallowed by it eventually

how are galaxies and quasars related?

d. quasars are active supermassive black holes at the centers of galaxies

compared to the mass of our own milky way galaxy, the total mass we estimate for the andromeda galaxy is a. a lot smaller b. a little bit smaller c. exactly the same d. somewhat bigger e. not something we can measure

d. somewhat bigger

when scientists say that "black holes have no hair", what do they mean? a. that the event horizon of a black hole is very smooth and does not have parts that jut out b. that if you threw something toward a black hole )a rabbit, say) it would quickly be ripped apart into small pieces c. that time near a black hole slows down so much our hair would not grow at a normal rate d. that once a black hole forms, very little information can be extracted from it about the material that is now inside e. no one knows what this means; regular people are not meant to figure out some of the weird things physicists say about black holes

d. that once a black hole forms, very little information can be extracted from it about the material that is now inside

which of the following statements about the nuclear bulge of our galaxy is false? a. it is significantly thicker than the disk of the galaxy b. it typically consists of older stars c. it is difficult for us to see with visible light because of cosmic dust d. the best way to learn more about it is to observe higher energy radiation, such as ultraviolet and x-rays e. there is evidence that it is not exactly spherical, but elongated

d. the best way to learn more about it is to observe higher energy radiation, such as ultraviolet and x-rays

if a nearby galaxy still acts like a quasar today, what is the most likely explanation?

d. the galaxy must be undergoing a collision with another galaxy that is providing fresh fuel for its central black hole

how do quasars demonstrate that the universe evolves with time/ a. there were very few quasars long ago, and their numbers have been growing since b. quasars began emerging only about a billion years ago, and now there are many more than ever c. quasars have been around since the big bang, but the radiation they give off gets stronger and stronger as time in the universe goes on d. the number of quasars reached a maximum some time ago, and now the numbers have been declining e. quasars actually don't demonstrate any evolution; the number of quasars has been pretty constant for the entire history of the universe

d. the number of quasars reached a maximum some time ago, and now the numbers have been declining

a "galactic year" as define by astronomers is: a. the time it takes the earth to go around the sun (starting with when it's closest in its orbit to the center of the galaxy) b. the time it takes the outermost part of the solar system (the oort cloud) to rotate once relative to the galaxy c. the time it took the milky way galaxy to develop spiral arms d. the time it takes the sun to revolve once around the center of the milky way galaxy e. the time it will take the sun to become a red giant and expand into the galaxy

d. the time it takes the sun to revolve once around the center of the milky way galaxy

the reason type IA supernovae are useful to astronomers for determining distances to other galaxies is that a. they only occur in spiral galaxies, for which no other way of getting distances is available b. it is easy to measure the blueshift produced by such explosions c. they are much larger than many other objects that can be seen in galaxies d. they are very bright, and generally reach the same peak luminosity e. they produce very energetic pulars whose radio radiation can be detected across vast distances

d. they are very bright, and generally reach the same peak luminosity

one important way astronomers can learn in some detail about what happens when galaxies collide is

d. to simulate galaxy collisions on a large computer and watch what the simulation predicts

what have we learned from the work of harlow shapley and others about the location of the sun in the milky way galaxy? a. we are almost exactly in the center of a giant flat pinwheel b. we are very close the edge of the visible disk of the galaxy, more than 50,000 ly from the center c. we are high above the disk of the galaxy, about as far away as the most distant globular cluster d. we are in the disk of the galaxy, about 3/5 of the way from the center e. you can't fool me; because of all the dust, astronomers still have no idea where our sun is located in the milky way galaxy

d. we are in the disk of the galaxy, about 3/5 of the way from the center

Edwin Hubble was able to show that, with the exception of a few of the nearest galaxies, the farther a galaxy is from us, the a. brighter it looks b. bluer its color c. the later in its life we are seeing it d. the larger its halo is e. the faster it is moving away from us

e. the faster it is moving away from us

when astronomers make counts of how many quasars there are at different distances from us, what do they find? a. there are more quasars closer to us than farther away c the largest number of quasars is pretty much the same at every range of distances (as many are close to us as far away) b. the largest number of quasars can be found at about a distance of 1 million ly away from us d. the largest number of quasars were found exactly at the time of the big bang (when the universe began) have been declining steadily in numbers ever since e. the largest number of quasars can be seen at about the distance corresponding to a time when the universe was only 20% its current age (a time when the universe was still young)

e. the largest number of quasars can be seen at about the distance corresponding to a time when the universe was only 20% its current age (a time when the universe was still young)

which of the following can a black hole not "eat" (swallow)? a. a planet b. a cloud of gas and dust c. a star d. another black hole e. you can't fool me, black holes can eat anything

e. you can't fool me, black holes can eat anything

the type of galaxy that consists almost entirely of old stars and is thus less blue (more yellow and reddish) than the other type is _______

elliptical galaxy

in 3.75 million years, andromeda has approached the milky way true or false

fale b

a barred spiral galaxy is a type of spiral galaxy without a central bar, or one that is not a barred spiral galaxy true or false

false b

a binary black hole did not support the idea that black holes can grow to enormous masses in the centers of galaxies by merging with nearby galaxies true or false

false b

a large LMC, approximately 200,000 light-years away true or false

false b

all quasars have in common is that they appear to be huge source of energy with redshifts that indicate they are far away. true or false

false b

blackbody: a hypothetical perfect radiator that absorbs and distributes all radiation falling upon it true or false

false b

cepheus is a constellation in the southern sky true or false

false b

elliptical galaxy probably originated from the collision of two irregular galaxies true or false

false b

elliptical galaxy: a galaxy with an elliptical shape, little interstellar matter, and spiral arms true or false

false b

herschel constructed this cross section of the galaxy by counting stars in a horizontal direction 'true or false

false b

in 1785, william herschel made the first important discovery about the architecture of the milky way galaxy. using a large refracting telescope that he had built true or false

false b

the halo stars is the name given to the young formation of stars which encircle the outer edge of the milky way galaxy true or false

false b

the less massive the galaxy, the more massive the central black hole true or false

false b

_______ is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other

friction

the rotational center of the milky way is the _______ center

galactic

an asymmetrical galaxy having neither spiral arms nor an elliptical shape is called _______ galaxy

irregular

all ______ have in common is that they appear to be small sources of energy with redshirts that indicate they are far away

quasars

herschel was right about: the ____ of our system, but wrong about where the sun lies within the disk

shape

a flattened, rotating galaxy with pinwheel-like spiral arms winding outward from the galaxy's nuclear bulge is called ______galaxy

spiral

a large explosion that takes place at the end of a stars's life cycle is called _____

supernova

a stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a star true or false

true A

In general theory of relativity, the einstein field equations relate the geometry of space-time with distribution of matter within it true or false

true a

a black hole is a place in space where gravity pulls so much that even light cannot get out true or false

true a

a bulge is a tightly packed group of stars within a larger formation true or false

true a

a dwarf galaxy is a small galaxy composed of about 100 million up to several billion stars true or false

true a

a globular cluster is a spherical collection of stars that orbits a galactic core true or false

true a

a quasar might not be much larger than our solar system it releases as much energy as billions of stars true or false

true a

a supercluster is a large group of smaller galaxy clusters or galaxy groups true or false

true a

astronomers use the red-shift using hubble's law to find the distance to a remote quasar true or false

true a

collapsar is the shortened form to describe a collapse star. when an old star. when an old star no longer has enough fuel for significant fusion reactions. true or false

true a

dwarf elliptical galaxies are elliptical galaxies that are smaller than ordinary elliptical galaxies true or false

true a

galaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation true or false

true a

globular clusters are very tightly bound by gravity, which gives them their spherical shapes true or false

true a

stephan's quintet is a visual grouping of 5 galaxies of which 4 form the 1st compact galaxy group ever discovered true or false

true a

the bubbles in the galaxy may be evidence that the supermassive black hole at the center of our galaxy was a quasar a few million years ago true or false

true a

the colors of the galaxy change from the yellowish light of old stars in the center to the blue color of hot, young stars true or false

true a

the energetic jets are "spit out" from the chaotic accretion disks of supermassive black holes in directions that are perpendicular to the disk true or false

true a

the galactic center is the rotational center of the milky way true or false

true a

the milky way is the galaxy that contains the solar system, with the name describing the galaxy's appearance from earth true or false

true a

the rich galaxy cluster that is closest to our local group of galaxies is the virgo cluster true or false

true a

the spiral arms of m100, shown here, are bluer than the rest of the galaxy, indicating young, high-mass stars and star-forming regions true or false

true a

when the star gets closer still, the tide become stronger than the gravity holding the star together, and it breaks up into a streamer. true or false

true a