PHY 101 test 3 Questions

The very strong source of radio waves at the center of our Galaxy is called

Sagitarrius A

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

elliptical

What method would astronomers use to find the distance to a remote quasar?

finding the redshift and using Hubble's Law

Most spiral galaxies consist of

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

______ forces caused the gas in the thin disk to fragment into clouds or clumps with masses like those os star clusters

gravitaional

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

how far away from us each cluster was

which of the following is NOT a characteristic of a spiral galaxy?

it has quite a bit of gas and dust in it

What was especially noteworthy about the Sagitarrius Dwarf Galaxy when it was discovered among the small galaxies near the Milky Way?

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

How are galaxies and quasars related?

quasars are active supermassive black holes at the centers of galaxies

Why do galaxies collide, while stars almost never do?

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

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

supernova

What observation in astronomy, made AFTER the discovery of quasars, was a big help to astronomers in figuring out what quasars really were?

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

Once a black hole forms, the size of its event horizon is determined only by

the mass inside the event horizon

In the first direct detection of gravitational waves by LIGO in 2015, the waves came from

the merger of two black holes

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 hole are related?

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

Herschel was right about:

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

Dwarf elliptical galaxies are elliptical galaxies that are smaller than ordinary elliptical galaxies

true

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

true

Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered

true

What have we learned from the work of Harlow Shapley and others about the location of the sun in the milky way galaxy?

we are in the dis of the galaxy, about 3/5 of the way from the center

which of the following can a black hole not "eat" (swallow)?

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

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

bluer and smaller

which type of galaxy is observed to contain mostly older stars?

elliptical galaxies

you are in a freely falling elevator near the top of a tall building, as the elevator falls, your weight would be:

equal to zero- you would be weightless

To predict whether a star will ultimately become a black hole, what is the key property of the star we should look at?

mass

Compared to the mass of our own Milky Way Galaxy, the total mass we estimate for the Andromeda Galaxy is

somewhat bigger

Our Milky Way Galaxy is what type of galaxy

spiral

when astronauts aboard the international space station (ISS) in space let go of an orange, it just floats there. Why is that?

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

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

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

Edwin Hubble developed a classification scheme for galaxies. By what characteristic did he classify galaxies?

their shape

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

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

A bulge is a tightly packed group of stars within a larger formation

true

A globular cluster is a spherical collection of stars that orbits a galactic core

true

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

true

Astronomers use the red-shift and using Hubble's Law to find the distance to a remote quasar

true

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

true

Elliptical galaxy: a galaxy with an elliptical shape, little interstellar matter, and spiral arms

false

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

friction

what do we mean by gravitational forces?

gravitation al forces cause the gas in the disc to fragment into clouds or clumps with masses like those of star's clusters

Where would you look for the youngest stars in the Milky Way Galaxy?

in the disk

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

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

Which of the following statements about the nuclear bulge of our Galaxy is FALSE

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

Edwin Hubble was able to show that (with the exception of our nearest neighbors) the farther a galaxy is from us, the

the faster it is moving away from us

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

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

If a very distant galaxy looks blue overall astronomers, from this they can conclude that:

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

How do quasars demonstrate that the universe evolves with time?

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

The Andromeda Galaxy (our nearest spiral neighbor) has spectral lines that show a blue shift. From this we may conclude that:

this particular nearby galaxy is moving towards us

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

The rich galaxy cluster that is closest to our local group of galaxies is the virgo cluster

true

in general theory of relativity, the Einstein field equations relate the geometry of space time with the distribution of matter within it

true

Which of the following objects is considered useful to astronomers as a "standard bulb" for determining distances?

type Ia supernovae

what is the difference between unbarred and barred?

unbarred- type of spiral galaxy without a central barr barred- spiral galaxy with a central barr shaped struct6ure composed of stars

After several decades of observation, astronomers have concluded that quasars are

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

Which of the following objects do many astronomers believe is a black hole?

Cygnus X-1

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

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

why is the use of Hubble's law to measure distances galaxies so important to astronomers

because most galaxies are so far away the only way to get distance to them is the use of hubble's law

the ______ galaxy is the closest big galaxy to our Milky Way

Andromeda

Which type of galaxy is very difficult to see, but (astronomers recently realizes) may be very common?

Dwarf elliptical

The appearnece of four images of the same galaxy or quasar due to gravitational lensing by an intervening galaxy is called

Einstein's Cross

What location does this huge amount of energy come from?

From an accretion disk around a supermassive blackhole