Final Exam

Front 1

The region of the Sun that contains sunspots and granulation is the

Back 1

photosphere

Front 2

The region of the Sun that can be seen easily with the naked eye only during a total solar eclipse is the

Back 2

corona

Front 3

The region of the Sun that is 1.7 times hotter than the surface and is the primary source of ultraviolet (UV) radiation is the

Back 3

chromosphere

Front 4

The surface temperature of the Sun is approximately

Back 4

5,800 K

Front 5

When we observe the Sun in visible light, sunspots appear dark because

Back 5

they are cooler than the surrounding photosphere by about 2,000 K

Front 6

A blackbody curve shows the wavelength peak of the Sun's radiation is in the middle of the ___ region of the electromagnetic spectrum

Back 6

visible

Front 7

The solar corona is so hot it emits mainly ___ radiation

Back 7

x-ray

Front 8

The temperature of the Sun's ___ is about 15 x 10^6 k

Back 8

core

Front 9

Solar ___ is a flow of energetic particles constantly streaming outward from the Sun

Back 9

wind

Front 10

Solar ____ is the name given to a filament projecting outside the lib of the Sun wehre we can see it against the black background of space. These filaments are huge and can last for days

Back 10

prominence

Front 11

The sunspot cycle averages about ___ years long

Back 11

11

Front 12

At the center of the Sun, fusion converts hydrogen into

Back 12

helium, energy and neutrinos

Front 13

Solar energy leaves the core of the Sun in the form of

Back 13

photons

Front 14

Our Sun is of spectral type ___

Back 14

G

Front 15

Fusion in the sun works by the process known as the ___

Back 15

proton-proton chain

Front 16

Which one of the following star types is MOST like the sun

Back 16

F9 dwarf

Front 17

The magnitude a star would have if it were placed at a standard distance of 10 parsecs is its

Back 17

absolute magnitude

Front 18

A temperature-luminosity diagram of stars usually includes a diagonal band called the

Back 18

main sequence

Front 19

A binary star that varies in brightness as one component (Star A) passes in front of the other (Star B) is a

Back 19

eclipsing binary

Front 20

The MAIN value in the study of binary stars is the ability it gives astronomers to determine accurately the ___ of each star

Back 20

mass

Front 21

The period-luminosity relation applies to ___, supergiant stars that are very useful in measuring distances to nearby galaxies (Polaris is an example)

Back 21

Cepheid variables

Front 22

Star clusters with irregular shapes, composed of up to several thouseand stars, and containing relatively young stars are called ___ clusters

Back 22

open

Front 23

Star clusters with tight, spherical shapes, composed of up to a million stars, and containing old stars and little gas are called ___ clusters

Back 23

globular

Front 24

When thermal pressure outward balances gravity's inward pull on the gas in a star, we call this condition ___equilibrium

Back 24

hydrostatic

Front 25

Low-mass stars (like the Sun) are both with ___ or fewer solar masses

Back 25

2

Front 26

A stellar-sized hot body that derives its energy from an ongoing free-falling gravitational collapse (but not from thermonuclear reactions) is called a

Back 26

brown dwarf

Front 27

A star's main-sequence lifetime is the time the star spends on the main sequence as a

Back 27

hydrogen-fusing star

Front 28

Compared with low-mass stars, high-mass stars have main-sequence lifetimes that are

Back 28

a lot shorter

Front 29

___ pose the greatest hazard to communications satellites in Earth orbit

Back 29

Protons from the Sun

Front 30

Which one of the following is NOT a property of a star like the Sun when it is in its red giant phase

Back 30

Its lifespan at this stage is 10 million years of .1% of its stay on the main sequence

Front 31

Near the end of the red giant phase, when such a star becomes unstable, it may eject shells of gas into space, forming a

Back 31

planetary nebula

Front 32

The pressure that keeps a white dwarf from collapsing further as it cools comes from

Back 32

degeneracy pressure of packing electrons too closely

Front 33

A white dwar contains approximately the mass of ___ within the volume of the Earth

Back 33

The Sun

Front 34

The Chandrasekhar limit says that a white dwarf's mass cannot exceed ___ times the mass of the SUn, or the white dwarf will become too unstable and explode

Back 34

1.4

Front 35

If, after a supernova, the stellar core is less than 2.5-3 solar masses, the result will probably be a

Back 35

neutron star

Front 36

In descending order -hottest to coolest- the spectral classes are

Back 36

OBAFGKM

Front 37

Neutron stars pack the mass of the Sun (or greater) into an object that has a diameter of about

Back 37

10 km (half the length of Manhattan Island)

Front 38

In a black hole, the radius of the event horizon is called the ___ radius

Back 38

Schwarzchild

Front 39

Though no light escapes from a black hole, the existence of these objects can be inferred from X-ray observations of hot gas surrounding them in ___ disks

Back 39

accretion

Front 40

Supermassive black holes probably exist in

Back 40

the centers of most galxies and globular clusters

Front 41

As a red giant, a star will initiate hydrogen shell burning. Hydrogen shell buring proceeds at a higher rate than core hydrogen fusion did, resulting in the star becoming larger in radius and

Back 41

more luminous

Front 42

Suppose you drop a clock toward a black hole. As you look at the clock from a high orbit, what will you notice

Back 42

Time on the clock will run slower as it approaches the black hole, and light from the clock will be increasingly redshifted

Front 43

Which one of the following statements about black holes is NOT true

Back 43

A spaceship passing near a 10 solar mass black hole is much more likely to be destroyed than a spaceship passing at the same distance from the center of a 10 solar mass main-sequence star

Front 44

Which statement about pulsars is NOT thought to be true

Back 44

Pulsars can form only in close binary systems

Front 45

Stars like the Sun have two internal zones that tranpsort energy from the core to the surface. Name these two zones

Back 45

convection and radiation

Front 46

White dwarfs are dense, hot, inert cores of low-mass stars made primarily of the element carbon, which requires a temperature of ___ to begin fusion. Low-mass stars do not have enough mass to reach such a high temperature

Back 46

600 Million K

Front 47

The more massive a white dwarf, the

Back 47

smaller is its radius

Front 48

An isolated brown dwarf will

Back 48

remain a bown dwarf forever

Front 49

A star's position on the main sequence is fixed by one, fundamental property-the star's

Back 49

mass

Front 50

Degeneracy pressure prevents objects with masses below about ___ from becoming true stars

Back 50

.08 Msun

Front 51

Solar activity includes

Back 51

all of the above

Front 52

Aside from H2 and He, the MOST abundant "heavy" molecule found in molecular clouds is

Back 52

CO

Front 53

In a big molecular cloud, about half of teh elements heavier than helium are found in

Back 53

microscopic, solid grains of interstellar dust

Front 54

Will our Sun ever undergo a white dwarf supernova explosion. Why or why not

Back 54

No, because it is not orbited by another star