Astronomy: Exam III

b. the mass inside the event horizon

*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

Gravitational

*_________________ forces caused the gas in the thin disk to fragment into clouds or clumps with masses like those of star clusters.

supernova

A _________ is a large explosion that takes place at the end of a star's life cycle.

collapsar

A ___________ is a massive star that undergoes gravitational collapse especially after colliding with another star.

black hole

A _____________ is a place in space where gravity pulls so much that even light cannot get out.

binary star

A _____________ is a star system consisting of two stars orbiting around their common barycenter.

binary black hole

A _____________ is a system consisting of two black holes in close orbit around each other.

Blackbody

A ______________ is a hypothetical perfect radiator that absorbs and reemits all radiation falling upon it

black holes

LIGO found that gravitational waves were produced in the final fraction of a second of the merger of two _________.

binary star systems

Like black holes, binary black holes are often divided into stellar binary black holes, formed either as remnants of high-mass ____________ or by dynamic processes and mutual capture.

stars, dust

Many _________ and dark clouds of ________ combine to make a spectacular celestial sight of our home Galaxy, the Milky Way.

solar masses

Stellar black holes have masses ranging from about 5 to several tens of ____________.

multiple star systems

Systems of two or more stars are called ________________.

matter

The gravity in a black hole is so strong because _______ has been squeezed into a tiny space.

Gravitational waves

______________ are disturbances in the curvature of spacetime, generated by accelerated masses, that propagate as waves outward from their source at the speed of light.

Gravitational waves

________________ are disturbances in the curvature of spacetime, generated by accelerated masses, that propagate as waves outward from their source at the speed of light.

Galaxy mergers

________________ can occur when two (or more) galaxies collide.

Supernova

*A large explosion that takes place at the end of a star's life cycle is called _______________.

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

*After several decades of observation, astronomers have concluded that quasars are: a. very powerful and compact sources of energy at the centers of distinct galaxies b. projectiles shot our 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

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

*By examining rich clusters of galaxies, such as the Coma Clusters, astronomers have discovered that spiral galaxies: a. grow to be very large and bright at the centers of these clusters b. turn out to be most of the galaxies in such clusters, and many are found throughout each cluster c. do not exist at all in such clusters d. are found mostly in the outer regions of such clusters, not in the middle e. are all tilted exactly the same way in such cluster; all their disks are fully aligned

d. somewhat bigger

*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

c. their shape

*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

e. the faster it is moving away from us

*Edwin Hubble was able to show that (with the exception of our nearest neighbors) 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

a. the more massive the galaxy, the more massive the central black hole

*For galaxies that have supermassive black holes at their centers, how do astronomers find that the mass of the host galaxy and the mass of the black hole are related? a. the more massive the galaxy, the more massive the central black hole b. the more massive the galaxy, the less massive the central black hole c. all supermassive black holes have roughy the same amount of mass d. once the mass of a galaxy reaches a certain size, it is not possible to form a black hole in the center at all; only galaxies smaller than this limit can have central black holes e. none of the above

a. bluer and smaller

*Galaxies that we see as they were 11 billion years ago or more, as compared to galaxies today, are generally: a. bluer and smaller b. redder and smaller c. redder and larger d. bluer and larger e. pretty much the same

a. the shape of our system, but wrong about where the Sun lies within the disk

*Herschel was right about: a. the shape of our system, but wrong about where the Sun lies within the disk b. where the Sun lies within the disk, but wrong about he shape of our system c. the shape of our system, and where the Sun lies within the disk d. none of the above

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

*How are galaxies and quasars related? a. quasars can be seen in front of galaxies, but they have nothing to do with them b. quasars can only be seen behind galaxies, but they have nothing to do with them c. quasars and galaxies are never seen together, and they have nothing to do with each other d. quasars are active supermassive black holes at the centers of galaxies e. quasars are a complete mystery; so it is not possible to say how they might be related to galaxies

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

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

*If a nearby galaxy still acts like a quasar today, what is the most likely explanation? a. the galaxy was formed recently, and is just now going through its "adolescence" b. the galaxy must have an enormous Doppler shift and must have traveled here from a large distance away c. the galaxy must be made entirely of very massive stars; very few low mass stars exist in it d. the galaxy must be undergoing a collision with another galaxy that is providing fresh fuel for its central black hole e. the dark matter in the galaxy must be undergoing a transformation into matter we can see

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

*If a very distant galaxy looks blue to astronomers, from this they can conclude that: a. the galaxy is moving toward us at great speed b. the galaxy must have a lot of young stars and thus active star formation must still be going in it c. the galaxy must be composed mostly of very old stars d. the galaxy must not be especially massive when compared to most galaxies e. the galaxy must have had a personal tragedy of some sort and needs a lot of love

c. equal to zero - you would be weightless

*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. the merger of two black holes

*In the first direct detection of gravitational waves by LIGO in 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 U.S. who want their government to work well for them

d. flat, rotating disk containing stars, gas, dust, and bulge

*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

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

*One important way astronomers can learn in some detail about what happens when galaxies collide is: a. to watch the Andromeda Galaxy (M31), which is on a collision course with us, for a decade b. to look at the supermassive black hole at the center of the Milky Way c. to examine the satellite galaxies presently orbiting the Milky Way d. to simulate galaxy collisions on a large computer and watch what the simulation predicts e. to look at videos of car accidents that are particularly violent

b. spiral

*Our Milky Way Galaxy is what type of galaxy? a. elliptical b. spiral c. dwarf elliptical d. irregular e. none of the above

b. this particular nearby galaxy is moving toward us

*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 toward us c. this galaxy has merged with the Milky Way and is now part of it d. this particular nearby galaxy is moving away from us e. this galaxy has an unusual number of very bright and hot O-Type stars in it

Andromeda

*The ______________ galaxy is the closest big galaxy to our Milky Way.

Einstein Cross

*The appearance of four images of the same galaxy or quasar due to gravitational lensing by an intervening galaxy is called _________ __________.

Elliptical

*The type of galaxy that consists almost entirely of old stars and is thus less blue (more yellow and reddish) than the other types is ____________.

a. Sagittarius A

*The very strong source 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

c. how far away from us each cluster was

*To map out how clusters of galaxies are distributed in the universe, astronomers needed to know where each cluster was in the sky AND: a. how many galaxies were in each cluster b. how blue or red the galaxies in each cluster were c. how far away from us each cluster was d. whether any of the galaxies in each cluster acted like quasars e. whether any gravitational lensing could be seen in each cluster

a. mass

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

True

*True or False: A bulge is a tightly packed group of stars within a larger formation.

True

*True or False: A globular cluster is a spherical collection of stars that orbits a galactic core.

True

*True or False: A stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a star.

True

*True or False: Astronomers use the redshift and Hubble's Law to find the distance to a remote quasar.

True

*True or False: Collapsar is the shortened form to describe a collapsed star. When an old star no longer has enough fuel for significant fusion reactions.

True

*True or False: Dwarf Elliptical Galaxies are elliptical galaxies that are smaller than ordinary elliptical galaxies.

False

*True or False: Elliptical Galaxy: A galaxy with an elliptical shape, little interstellar matter, and spiral arms.

True

*True or False: Gravitational forces caused the gas in the thin disk to fragment into clouds or clumps with masses like those of star clusters.

True

*True or False: In the General Theory of Relativity, the Einstein field equations relate the geometry of space-time with the distribution of matter within it.

True

*True or False: Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered.

True

*True or False: 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

*True or False: The rich galaxy cluster that is closest to our Local Group of galaxies is the Virgo Cluster.

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

*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 to the edge of the visible disk of the Galaxy, more than 50,000 lightyears 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. 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 on an H-R Diagram

b. the discovery that the Milky Way Galaxy has a black hole at the center with enough mass for 4 million Suns

*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 Way Galaxy has a black hole at the center with enough mass for 4 million 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-Haro objects around newly forming stars

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

*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 supermassive black hole in the center much larger than the Milky Way's 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 be seen on any photographs

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

*When astronauts aboard the International Space Station (ISS) in space let go of an orange, it just floats there. Why? a. the ISS is so far from the 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, so 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

c. in the disk

*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 changes of finding a very young star are the same, wherever in the Galaxy I look

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

*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

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

*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

c. Cygnus X-1

*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

a. type Ia supernovae

*Which of the following objects is considered useful to astronomers as a "standard bulb" for determining distances? a. type Ia supernovae 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. the central bulges of spiral galaxies formed first and their disks formed later

*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 b. star formation in the spiral galaxies is much higher today than it was 8 billion years ago c. spiral galaxies formed pretty quickly after the Big Bang and already looked then the way they look today d. spiral galaxies have evolved until today they are all "red and dead," containing just old stars and showing almost no current star formation e. spiral galaxies cannot have a central super-massive black hole, so astronomers don't understand just how they formed

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

*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

b. elliptical

*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

c. dwarf elliptical

*Which type of galaxy is very difficult to see, but (astronomer recently realized) may be very common? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above

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

*Why do astronomers think that there 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 b. quasars are supermassive black holes at the centers of galaxies, and such black holes are constantly losing mass and thus getting less and less able to pull on anything c. quasars tend to merge all the time, and so there are fewer and fewer of them as time goes on d. quasars are caused by many supernovae going off at the same time, and massive stars only exploded in the early history of the universe; they don't explode today e. no one has the slightest idea on how to answer this question; it is completely unsolved

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

*Why do galaxies collide, which stars almost never do? a. stars have a very strong negative charge on them, so they repel other stars that get near b. stars don't have very much mass, so their gravity is very small and can't pull things well c. stars are much further apart (compared to how big they are) than galaxies are d. stars are surrounded by planets, which prevent collisions; galaxies are not e. actually, stars collide all the time, but astronomers don't have any way of observing it

Friction

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

stellar black hole

A _______________ is a black hole formed by the gravitational collapse of a star.

blackbody curve

A ________________ is the curve obtained when the intensities of radiation from blackbodies at particular temperatures are plotted against wavelength.

escape velocity, light

A black hole is an object whose gravity is so strong that the ______________ from it exceeds the speed of the __________.

collapses

A black hole is created when a massive stars __________ at the end of its life.

fusion reactions

A collapsed star occurs when an old star no longer has enough fuel for significant _____________ __________.

mass collapse

A star about five times as massive as the Sun will undergo a much more violent collapse, known as a ___________.

General Relativity Theory

According to the ____________________, the observed gravitational effect between masses results from their warping of spacetime

galactic mergers

Binary supermassive black holes are believed to be a result of _______________.

black hole

Collapsars are massive stars, which, in the course of merging with a compact companion, undergo core collapse, leading to a ____________.

binary

Cygnus X1 is in a ________ star system.

Jupiter, Highlands, Maria

Galileo used his telescope to discover the four moons of ________ and the ____________ and ________ on the moon.

directions, reflecting

Herschel constructed this cross section of the Galaxy by counting stars in various ___________ using a ____________ telescope.

surface, straight up

If a star collapses so that it is just a little larger than a black hole, all the light paths, except the one straight up, curve back to the ___________. When the star shrinks inside the event horizon and becomes a black hole, a beam directed _____________ returns.

neutron star

In a mass collapse, the outer layers of the star will be ejected into space in a supernova explosion, leaving behind a collapsed star called a __________.

normal, lighter, heavier

In an elevator at rest, you feel your ______ weight. In an elevator that accelerates as it descends, you would feel _______ than normal. In an elevator that accelerates as it ascends, you would feel _________ than normal.

spacetime, matter

In general theory of relativity, the Einstein field equations relate the geometry of _____________ with the distribution of ___________ within it.

Pueblo building

The ______________ is an American Indian settlement of the southwestern US, especially one consisting of multistoried adobe houses built by the Pueblo people.

hypernova, gamma ray

The gravitational collapse of star is observed as a ______________ explosion or as a ___________ burst.

galaxies, friction

The gravitational interactions between ____________ and the __________ between the gas and dust have major effects on the galaxies involved.

disk

The material pulled away by a black hole from a companion stars forms a _______ that rotates around the black hole.

True

True or False: A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it.

True

True or False: Galaxy mergers are the most violent type of galaxy interaction.

stellar-mass black hole

What is another name for a stellar black hole?

Milky Way Galaxy

Which galaxy contains the solar system?

John Wheeler

Which physicist popularized the term black hole starting in the late 1960s?

Karl Schwarzschild

Which scientist was the first to demonstrate mathematically that a black hole is possible and to determine the size of a nonrotating black hole's event horizon?

Uranus, telescopes, Galaxy, space, stars

William Hershel discovered the planet ___________, built several large ____________, and made measurements of the Sun's place in the _________, the Sun's motion through ________, and the comparative brightness's of ______.

Cygnus X-1

___________ is a galactic X-ray source in the constellation Cygnus, and the first such source widely accepted to be a black hole.

Collapsar

___________ is the shortened form to describe a collapsed star.