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A nova includes...

Mass transfer into a white dwarf in a binary system

Most important property in how a star will evolve and die?

Mass

A white dwarf can explode when...

its mass exceeds the Chandreskhar limit

A type II supernova occurs when...

iron builds up in the core

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some examples of which type of dying star exhibit rapid pulses that were originally suspected to be communications from extraterrestrials?

Neutron Star

the average density of a neutron star approaches...

about 10^14 kg/m^-3

Pulsars show all of the following except...

high temp. fusion reactions

Lighthouse model explains

rotating neutron star generates observable beam of light

Many millisecond pulsars lie within

Globular clusters

Based on star counts, 100 years ago most astronomers thought galaxies were

circular disk, 10 kpc wide, 2 kpc thick

Location of the galactic center was first found by Harlow Shapley using

RR lyrae variables in globular clusters

Which is the correct description of the sun's location within the milky way?

above the disc, about 1/3 of the galactic radius from the center

Why was Herschel's strategy for mapping out galaxy flawed?

he relied on visual wavelengths, which are obscured by dust

Curtis was right in arguing the milky way was

similar to spiral nebulae, blocking our view of spiral nebula in the galactic plane

Harlow Shapely was correct in arguing the Milky Way was

much larger than previously expected

Region on the HR diagram where pulsating variables occur is called the

instability strip

All RR lyrae stars have about the same

luminosity (of about 100 suns)

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A star in the instability strip of the HR diagram would

vary in temperature and radius

most of the new star formation in the Galaxy is found in the...

spiral arms

the orbits of Population II stars (older stars) have been compared to

comets around the sun

galactic year is the time for our solar system to orbit the galaxy; it is about...

225 million years

detailed measurements of the disk and central bulge region of our galaxy suggest our Milky Way is a...

barred spiral galaxy

The "aspect ratio" of thickness to width of the galactic disk is about

1:100

which sequence of formation by age is correct, oldest to youngest?
- open clusters, emission nebulae, globular clusters

globular clusters, emission nebulae, open clusters

What use are 21 cm radio waves to galactic astronomers?

their doppler shifts allow us to map the motions of the hydrogen in the galaxy

leading explanation for the existence of spiral arms are

passages of spiral density waves

Which of the following is most like the rotation of stars in the disk of the Milky Way?

Cars moving at a constant speed on a circular race track

What two observations allow us to calculate the Galaxy's mass?

sun's orbital velocity and its distance from the Galactic Centre

Which method relies on the mass of a dark object revealing its presence...

temporary brightening of a distant star by a gravity lens

most of the mass of the Milky Way seems to exist in the form of...

dark matter (out in the halo)

Proposed WIMPS would be massive like ______, but more elusive than __________, however this is not yet proven

neutrons, neutrinos

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A spherical galaxy, like M 87, which looks like a monster globular cluster, is type...

E0

Flattest of elliptical class are class...

E7

Which type of galaxy has a stellar disk, but without gas and dust?

S0 (Spiral Galaxy)

You see a spiral galaxy with a large central bulge and tightly wrapped arms. It would be a...

Spiral galaxy (Sa)

An intermediary wound barred spiral galaxy would, in Hubble's system, be...

SBb

Hubble's classification, which type of galaxy has a small bulge and loose, widely spread, poorly defined spiral pattern

Sc

In Hubble's classification, which type of galaxy has no stellar disk, no gas, and no dust?

Elliptical (E0)

Which statement is true about ages and masses of spiral and elliptical galaxies?

Both types are about the same age, but spirals vary less in mass

Which of these would be made up of only Population II stars?

elliptical galaxies

Most galaxies in the local group are...

small ellipticals like the companions to M31 in Andromeda

Most of the stars in the Local Group are in

big spirals like our galaxy (M31)

Within the boundaries of the constellations of Coma and Virgo are found...

largest nearby superclusters of galaxies

Why does the cepheid "standard candle" have limited usefulness beyond 20 mpc?

cepheids are too faint to be seen beyond that distance, even with HST

Which of the following paraphrases Hubble's Law?

the greater the distance to a galaxy, the greater the redshift

The Tully-Fisher relation is between the galaxy's luminosity and its....

rotation

For finding the distance to M31, Hubble relied upon...

cepheid variables in its spiral arms

While examining the spectrum of a galaxy you find that all the hydrogen lines are shifted to the longest wavelengths. The galaxy is...

moving away from us

Quasars usually have their distances measured by what technique?

Hubble's Law

Why do some quasars have red shifts greater than 1?

they are very distant, with relativistic red shifts that take into account dilation of space-time, as Einstein predicted

Quasars were at cosmological distance that appeared like ordinary faint stars meant that

they must be producing such large quantities of energy that even fusion could not explain

In active galaxies, their central engines may be temporarily fed by...

nearby galaxies

A billion solar mass black hole would still have a radius of only...

20 AU

Synchotron radiation produces a _______ spectrum

continuous non-thermal

The energy radiated by a typical quasar requires that its black hole accrete about

ten solar masses a year

When spiral galaxies do collide, the impact is greatest on their...

giant molecular clouds

due to the galaxy density and collisions, _______ are in the centres of clusters

spirals

Pre-galactic blobs had masses similar to...

Large Magellanic clouds

why are super massive galaxies often found at the cores of rich galaxy clusters?

they are the result of many galactic mergers; one galaxy growing at the expense of others

some quasars show absorption spectra with a smaller redshift than their emission spectra, this indicates that...

there is cooler gas between us and the quasar

Astronomers think most galaxy interaction took place at redshifts greater than 1 because...

clusters were more compact

why is thought that quasars probably spend only a fairly short time in their highly luminous place?

because a black hole cannot power a highly luminous quasar for more than a few million years

Energy radiated from a typical quasar requires that its black hole accrete about...

10 solar masses a year

The ratio of bulge mass to black hole mass is roughly...

200 to 1

What is the Great Wall?

large sheet of galaxies measuring 70 mpc by 100 mpc

Gravitational lensing of distant, faint irregular galaxies may be the key to...

mapping dark matter

Homogeneity and isotropy taken as assumptions regarding the structure and evolution of the universe, are known as...

cosmological principle

Hubble time is expressed as

1/H (13 Billion years?)

Redshift of galaxies is correctly interpreted as...

space itself is expanding with time, so the photons are stretched while they travel outside of space

What does Hubble Law imply about the universe?

the universe had a beginning and has expanded since, giving it a finite age

The sky is dark at night because...

all the light from the objects in space hasn't reached us yet

What is the Big Bang?

the event that started the expansion of the universe

If the density of the universe is greater than the critical density, this means that...

the universe is expanding at a rate less than the escape speed of the universe

In the closed universe model, the geometry of space time in two dimensions resembles the surface of a...

sphere

in Robert Frost's classic poem, when he ends with "ice will suffice", the universe is...

open

In a closed universe, a beam of light will...

come back to where it originated

Critical evidence for cosmic acceleration in 1998 came from two teams of astronomers, both observing...

type I supernovae

the universal accelerating force could not be considered...

dark matter

Matter made out of protons, neutrons, and electrons in the universe accounts for that percent of the total mass of the universe?

less than 4%

in the critical density universe now proposed, the ratio of dark energy to matter is about...

3 to 1

in our best current theory, the first quasars formed about...

13 billion years ago

According to the turn off points of the oldest globular clusters, they formed about...

12 billion years ago

Discovery of the cosmic microwave background was important because...

experimental verification of a prediction from the Big Bang Theory

What temp. has the Big Bang has cooled to by now?

just over 2.7 K

Photons from the microwave background have not interacted with matter since the universe was how old?

400,000 years old

of the normal elements around us, the Big Bang produced...

hydrogen and helium

at the end of the first 15 minutes, the mass ratio of H/He was about...

75/25

The scarcity of what isotope is a critical test of the density of the present cosmos?

deuterium

about how hot was the Big Bang when matter and energy "decoupled"?

3,000 K

What did the cosmic microwave background tell cosmologists about the early universe?

horizon problem in that the microwave background is too isotropic

the best answer to both the flatness and horizon problem is...

the inflationary epoch

which of these could be considered as "hot dark matter"?

neutrinos

MASTERING ASTRO - Most of the energy of the supernova is carried outward via a flood of...
A.) gamma rays
B.) protons
C.) neutrinos
D.) positrons
E.) helium nuclei

Neutrinos

A 20 solar mass star will stay on the main sequence for 10 million years, yet its iron core can exist for only a...
A.) century.
B.) year.
C.) week.
D.) month.
E.) day

day

As a star's evolution approaches the Type II supernova, we find...
A.) helium to carbon fusion takes at least 100 million K to start.
B.) the heavier the element, the higher the temperature to fuse it.
C.) photo disintegration of iron nuclei begins at 10 billion K to ignite the supernova.
D.) the heavier the element, the less time it takes to make it.
E.) All of the above

All of the above

Rank the following steps that lead to a Type I supernova event in order of when they occur from first to last.
-white dwarf at Chandrasekhar limit, accretion disk with growing white dwarf, carbon fusion begins throughout, detonation

accretion disk with growing white dwarf, white dwarf at Chandrasekhar limit, carbon fusion begins throughout, detonation

the radius of a white dwarf is determined by a balance between the inward force of gravity and the outward push of ________
A.) electron degeneracy pressure
B.) nova
C.) massive star supernova
D.) white dwarf limit (1.4 solar masses)
E.) accretion disk
F.) white dwarf supernova

electron degeneracy pressure

A(n) _________ occurs when hydrogen fusion ignites the surface of a white dwarf in a binary system
A.) electron degeneracy pressure
B.) nova
C.) massive star supernova
D.) white dwarf limit (1.4 solar masses)
E.) accretion disk
F.) white dwarf supernova

nova

A(n) ___________ occurs when fusion creates iron in the core of a star
A.) electron degeneracy pressure
B.) nova
C.) massive star supernova
D.) white dwarf limit (1.4 solar masses)
E.) accretion disk
F.) white dwarf supernova

massive star supernova

A(n) white dwarf in a close binary system will explode as a supernova if it gains enough mass to exceed the _________
A.) electron degeneracy pressure
B.) nova
C.) massive star supernova
D.) white dwarf limit (1.4 solar masses)
E.) accretion disk
F.) white dwarf supernova

white dwarf limit (1.4 solar masses)

A(n) _________ consists of hot, swirling gas captured by a white dwarf (or neutron star or black hole) from a binary companion star
A.) electron degeneracy pressure
B.) nova
C.) massive star supernova
D.) white dwarf limit (1.4 solar masses)
E.) accretion disk
F.) white dwarf supernova

accretion disk

A(n) ____________ can occur only in a binary system, and all such events are thought to have the same luminosity
A.) electron degeneracy pressure
B.) nova
C.) massive star supernova
D.) white dwarf limit (1.4 solar masses)
E.) accretion disk
F.) white dwarf supernova

white dwarf supernova

In a neutron star, the core is....
A.) electrons and protons packed so tightly they are in contact.
B.) made of compressed neutrons in contact with each other.
C.) primarily iron and silicon.
D.) constantly expanding and contracting.
E.) no longer rotating.

made of compressed neutrons in contact with each other

An object more massive than the sun, but roughly the size of a city, is a...
A.) white dwarf.
B.) brown dwarf.
C.) red dwarf.
D.) neutron star.
E.) supernova remnant.

neutron star

What would happen if mass is added to a 1.4 solar mass white dwarf?
-The star would erupt as a carbon detonation (type I) supernova.
-The star's radius would increase. -The star would immediately collapse into a black hole.
-The core would collapse as a type II supernova.
-The star would explode as a nova.

the star would erupt as a carbon detonation (type I) supernova

Which of these does not exist?
-a million solar mass black hole -a 6 solar mass black hole
-a 6.8 solar mass neutron star
-a 1.0 solar mass white dwarf
-a 0.06 solar mass brown dwarf

a 6.8 solar mass neutron star

the most rapidly "blinking" pulsars are those that...
-spin fastest.
-are oldest.
-are most massive.
-are hottest.

spin fastest

X-ray bursters are similar to novae, except the collapsed star is a neutron star, not a white dwarf.

True or False

True

Three terrestrial-sized planets in orbits of a fraction of an AU have been found near
Supernova 1987A.
a magnetar.
Cygnus X-1.
a millisecond pulsar.
a white dwarf.

a millisecond pulsar

What are X-ray bursters?
They are the central sources of energy for planetary nebulae.
They are neutron stars on which accreted matter builds up, then explodes in a violent nuclear explosion.
They are violent energy sources known to lie at the heart of the Milky Way and similar massive galaxies.
They are rapidly rotating black holes whose precession points their poles toward us on occasion.
They are very massive stars that explode as supernovae, emitting bursts of X- rays and gamma-rays in the process.

They are neutron stars on which accreted matter builds up, then explodes in a violent nuclear explosion.

Almost half of all known millisecond pulsars are found in what type of object?
open clusters
emission nebulae
giant molecular clouds
globular clusters
supernova remnants

globular clusters

To which of these phenomena are X-ray busters most similar?
hypernovae
novae
type II supernovae
type I supernovae
planetary nebulae

novae

Gamma-ray bursts are observed to occur...
approximately uniformly over the entire sky.
throughout the Milky Way Galaxy.
near pulsars.
mainly near the Sun.

approximately uniformly over the entire sky

A proposed explanation for gamma-ray bursters is
coalescence of a neutron star binary.
hypernova-making black holes and bi-polar jets.
collisions between two white dwarfs.
Both A and B are possible.
All three are possible.

Both A and B are possible

Rank these objects based on their diameter, from largest to smallest. (Note that the neutron star and black hole in this example have the same mass to make your comparison easier, but we generally expect black holes to have greater masses than neutron stars.)

Jupiter, one-solar-mass white dwarf, main-sequence star of spectral type A, a two-solar-mass neutron star, the event horizon of a two-solar-mass black hole, the moon

main-sequence star of spectral type A, Jupiter, one-solar-mass white dwarf, the moon, a two-solar-mass neutron star, the event horizon of a two-solar-mass black hole

Rank these objects based on their mass, from largest to smallest.

main-sequence star of spectral type M, a one solar mass white dwarf, typical black hole (formed in a supernova), typical neutron star, Jupiter, the Moon

typical black hole (formed in a supernova), typical neutron star, a one solar mass white dwarf, main-sequence star of spectral type M, Jupiter, the Moon

Listed following are several astronomical objects. Rank these objects based on their density, from highest to lowest.

- singularity of a black hole, main sequence star, typical neutron star, one solar mass white dwarf

singularity of a black hole, typical neutron star, one solar mass white dwarf, main sequence star

Listed following are distinguishing characteristics of different end states of stars. Match these to the appropriate consequence of stellar death for a White Dwarf

-in a binary system, it can explode as a supernova
-usually has a very strong magnetic field
-viewed from afar, time stops at its event horizon
-size defined by its Schwarzschild radius
-sometimes appears as a pulsar
-has a mass no greater than 1.4MSun
- typically about the size (diameter) of Earth
- supported by electron degeneracy pressure

in a binary system, it can explode as a supernova, has a mass no greater than 1.4MSun, typically about the size (diameter) of Earth, supported by electron degeneracy pressure

Listed following are distinguishing characteristics of different end states of stars. Match these to the appropriate consequence of stellar death for a Neutron Star
-in a binary system, it can explode as a supernova
-usually has a very strong magnetic field
-viewed from afar, time stops at its event horizon
-size defined by its Schwarzschild radius
-sometimes appears as a pulsar
-has a mass no greater than 1.4MSun
- typically about the size (diameter) of Earth
- supported by electron degeneracy pressure

sometimes appears as a pulsar, usually has a very strong magnetic field

Listed following are distinguishing characteristics of different end states of stars. Match these to the appropriate consequence of stellar death for a Black Hole
-in a binary system, it can explode as a supernova
-usually has a very strong magnetic field
-viewed from afar, time stops at its event horizon
-size defined by its Schwarzschild radius
-sometimes appears as a pulsar
-has a mass no greater than 1.4MSun
- typically about the size (diameter) of Earth
- supported by electron degeneracy pressure

viewed from afar, time stops at its event horizon, size defined by its Schwarzschild radius

Black holes result from stars having initial masses
- less than the mass of the Sun.
- between 1 and 2 times the mass of the Sun.
- up to 8 times the mass of the Sun.
- more than 25 times the mass of the Sun.

more than 25 times the mass of the Sun.

When another spaceship is moving by you (at constant velocity), you will measure the spaceship to be shorter than its rest length, while passengers on that ship will measure your length to be shorter. Imagine that you and the passengers on the other ship are arguing (by radio) about who really is the one that has become shorter. To settle the argument, you agree to meet up on Mars and put the two spaceships next to each other to see which one is really shorter. What will you find when you meet up on Mars?
Your spaceship really is shorter than the other one.
Both spaceships are the same length.
The other spaceship really is shorter than yours.

Both spaceships are the same length

The figures below show several different astronomical objects. Rank the objects based on the strength of the gravitational force that would be felt by a spacecraft traveling at a distance of 10 AU from the center of each of the objects, from weakest to strongest.
- the sun, black hole mass, red giant mass, white dwarf mass

all the same

The figures below show several different astronomical objects. Rank the objects based on the amount that spacetime is curved (relative to flat spacetime) at a distance of 10 AU from the center of each of the objects, from least to greatest. If two (or more) cases are equal, show this equality by dragging one figure on top of the other(s).
- the sun, black hole mass, red giant mass, white dwarf mass

all the same

The figures below show several different astronomical objects. Rank the objects based on the amount that spacetime is curved (relative to flat spacetime) very near the surface (or event horizon) of the objects, from least to greatest.
- the sun, black hole mass, red giant mass, white dwarf mass

red giant mass, the sun, white dwarf mass, black hole mass

The figures below show several different astronomical objects. Rank the objects based on the acceleration a spaceship would have as it passed very near the surface (or event horizon) of each object, from smallest to largest.
- the sun, black hole mass, red giant mass, white dwarf mass

red giant mass, the sun, white dwarf mass, black hole mass

Where does an object on an elliptical orbit experience the greatest acceleration?
where spacetime has the most curvature
where spacetime has the least curvature
The acceleration is the same everywhere along the orbit.

where spacetime has the most curvature

Imagine that the Sun could be turned into a black hole without changing its mass. How would Earth's orbit change?
Earth's orbit would change from elliptical to unbound.
Earth's orbit would move farther from the Sun.
Earth would be sucked into the black hole.
Earth's orbit would not change.

Earth's orbit would not change.

Imagine that the Sun gained mass without changing its radius. How would the structure of spacetime change at the distance of Earth's orbit?
The structure of spacetime would stay the same.
Spacetime would become more curved at Earth's orbit.
Spacetime would become flatter (less curved) at Earth's orbit.
A black hole would engulf the Earth.

Spacetime would become more curved at Earth's orbit.

Listed following are several locations in the Milky Way Galaxy. Rank these locations based on their distance from the center of the Milky Way Galaxy, from farthest to closest.
- the edge of the central bulge, a cloud of gas and dust in the outskirts of the disk, our solar system, a globular cluster int he outskirts of the halo

a globular cluster in the outskirts of the halo, a cloud of gas and dust in the outskirts of the disk, our solar system, the edge of the central bulge

Imagine a photon of light traveling the different paths in the Milky Way described in the following list. Rank the paths based on how much time the photon takes to complete each journey, from longest to shortest. (USE NUMBERS)
- 1.) across the diameter of the galactic disk, 2.) from the sun to the center of the galaxy, 3.) through the disk from top to bottom, 4.) across the diameter of the central bulge, 5.) across the diameter of the galactic halo

5, 1, 2, 4, 3

Each item below belongs either with the population of disk stars or the population of halo stars of the Milky Way Galaxy. Match each item to the appropriate population (for Disk Stars (Yellow))
- youngest stars, stars whose orbits can be inclined at any angle, globular clusters, stars with the smallest abundance of heavy elements, stars that all orbit in nearly the same plane, the sun, oldest stars, high mass stars

youngest stars, the sun, stars that all orbit in nearly the same plane, high mass stars

Each item below belongs either with the population of disk stars or the population of halo stars of the Milky Way Galaxy. Match each item to the appropriate population (for Halo Stars (Green)) (USE NUMBERS)
- 1.) youngest stars, 2.) stars whose orbits can be inclined at any angle, 3.) globular clusters, 4.) stars with the smallest abundance of heavy elements, 5.) stars that all orbit in nearly the same plane, 7.) the sun, 8.) oldest stars, 9.) high mass stars

8, 3, 4, 2

The circular but relatively flat portion of the galaxy is the ________
- halo
- bulge
- disk
- spiral arm
- spiral galaxy
- globular cluster

disk

The first portion of the galaxy to form was the _______
- halo
- bulge
- disk
- spiral arm
- spiral galaxy
- globular cluster

halo

A tightly packed group of a few hundred thousand very old stars is a _________
- halo
- bulge
- disk
- spiral arm
- spiral galaxy
- globular cluster

globular cluster

A _________ stands out in a photo of a galaxy because it shines bright with light from massive young stars and glowing clouds of gas and dust
- halo
- bulge
- disk
- spiral arm
- spiral galaxy
- globular cluster

spiral arm

Our Milky Way galaxy is a _________
- halo
- bulge
- disk
- spiral arm
- spiral galaxy
- globular cluster

spiral galaxy

Stars orbiting in the ________ near the galaxy's center can have orbits highly inclined to the galactic plane

bulge

The first stars that formed in the Milky Way now...
orbit in the Galactic plane.
orbit closest to the Galactic center.
orbit in the same direction as the Milky Way spins.
have random orbits in the halo.

have random orbits in the halo

Population I stars came billions of years before Population II stars.
True
False

False

In our vicinity, the galactic disk is about 100 times wider than it is thick.
True
False

True

Most of the new star formation in the Galaxy is found in the...
spiral arms.
halo.
globular clusters.
galactic center.
bulge.

spiral arms

Matter belonging to the Galaxy can be traced out to ________ from the center.
50 kpc
5 kpc
8 kpc
15 kpc
200 kpc

50 kpc

The orbits of Population II stars have been compared to...
binary stars.
planets around the Sun.
comets around the Sun.
satellites around planets.
the accretion disc around a black hole.

comets around the sun

From the Sun, the distance to the Galactic Center is about
8 pc.
8,000 pc.
100,000 pc.
225 million pc.
100 billion pc.

8,000 pc

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