Exam 2

Question 1

The hottest zone in the sun is the

Answer 1

core

Question 2

The most common element in the sun is

Answer 2

hydrogen

Question 3

T OR F: The sun rotates at different rates at different latitudes on the sun

Answer 3

True

Question 4

The innermost part of the sun is the

Answer 4

core

Question 5

a region of the sun where energy is transported very slowly because the matter is densely packed; this is called the ___________.

Answer 5

radiative zone

Question 6

a region of the sun where vast bubbles of hot material move upward and then sink down, much like bubbling oatmeal or miso soup, called the ______________.

Answer 6

convective zone

Question 7

The layer where the Sun becomes opaque and we can not see further in is called its _________

Answer 7

photosphere

Question 8

Further outward is a region of thinner, hot gas, called the __________

Answer 8

chromosphere

Question 9

The Sun’s outermost layer, the _____, has very low density and extends for millions of miles

Answer 9

corona

Question 10

During a solar maximum, what phenomena should you expect to see enhanced compared to the average levels?

Answer 10

number of solar flares
number of sunspots
aurora on Earth

Question 11

Which of the following types of star is the coolest (has the lowest surface temperature)?

Answer 11

M

Question 12

T OR F: The amount by which the spectral lines of a star is redshifted tells astronomers how fast the star is moving away from us

Answer 12

True

Question 13

Astronomers use the term interstellar matter to refer to:

Answer 13

gas and dust that lies between stars 

Question 14

The red color we see on a lot of photographs of nebulae comes from which element?

Answer 14

hydrogen

Question 15

A type of star cluster that contains mostly very old stars is

Answer 15

a globular star cluster 

Question 16

Why can a star with a mass like our Sun not fuse (produce) further elements beyond carbon and oxygen?

Answer 16

because such a star just cannot get hot enough for the fusion of heavier nuclei 

Question 17

When a single star with a mass equal to the Sun dies, it will become a

Answer 17

white dwarf 

Question 18

If you want to find stars that are just being born, where are the best places to search?

Answer 18

in giant molecular clouds

Question 19

A star whose temperature is increasing but whose luminosity is roughly constant moves in what direction on the H-R diagram?

Answer 19

to the left 

Question 20

Astronomers identify the “birth” of a real star (as opposed to the activities of a protostar) with what activity in the star?

Answer 20

when nuclear fusion reactions begin inside its core 

Question 21

Everything we know about
stars comes from their light, and
they don’t all appear equally
bright, nor the same color; they
differ in:

Answer 21

Temperature
* Mass
* Energy emission
* Composition
* Etc.

Question 22

total amount of energy at all wavelengths that a star emits per
second.

Answer 22

luminosity

Question 23

the amount of a star’s energy that reaches a given area each second here on Earth

Answer 23

apparent brightness

Question 24

For two stars of the same apparent brightness, the star closer to the Sun will generally have

Answer 24

a lower luminosity

Question 25

formula for apparent brightness

Answer 25

luminosity / distance^2

Question 26

brightest stars are what magnitude

Answer 26

1

Question 27

faintest stars are what magnitude

Answer 27

6

Question 28

Which of the following quantities do you need in order to calculate a star’s luminosity?

Answer 28

distance and apparent brightness

Question 29

There are seven general categories of stellar spectra, corresponding to different temperatures. From hottest to coolest, those categories are

Answer 29

O B A F G K M (Oh Be A Funny Goat, Kick Me)

Question 30

The more massive stars are generally also the more

Answer 30

luminous

Question 31

A binary star system: A. Is composed by two stars B. Is held together by gravity C. Is useful to find the mass of the component stars D. Is not always visually detectable E. All of the above

Answer 31

E. All of the Above

Question 32

where most stars are

Answer 32

the main sequence

Question 33

What are the two most important intrinsic properties for classifying stars?

Answer 33

luminosity and surface temperature

Question 34

Apparent motion of object against distant background from two vantage points.

Answer 34

parallax

Question 35

A graph that shows how the brightness of a variable star changes with time is called a

Answer 35

light curve

Question 36

The interstellar medium consists of

Answer 36

gas and dust

Question 37

region of space that is clearly distinguishable through a telescope (dark or bright) , but is not sharply defined like a planet or a star

Answer 37

nebula

Question 38

glowing cloud of hot interstellar medium

Answer 38

emission nebula

Question 39

Study of the stars and galaxies through hydrogen signals

Answer 39

radio astronomy

Question 40

The reddish color of emission nebulae indicates that:

Answer 40

hydrogen gas is present

Question 41

If an interstellar cloud contracts to become a star, it is due to which force?

Answer 41

Gravitational

Question 42

Objects more massive than the Sun form into stars

Answer 42

Much faster, over tens of thousands of years

Question 43

spherical cluster of stars with the absence of massive main-sequence stars, and the heavily populated red giant region. Found away from the galactic plane

Answer 43

globular cluster

Question 44

What is a T-Tauri star?

Answer 44

A protostar about to become a star

Question 45

Once a star has reached the main sequence stage of its life, it derives its energy almost entirely from

Answer 45

the conversion of hydrogen to helium

Question 46

Helium begins to fuse extremely rapidly; within hours the enormous energy output is over, and the star once again reaches equilibrium

Answer 46

helium flash

Question 47

During formation, the Sun evolved toward the main sequence as shown in the figure. The Sun will evolve away from the main sequence when (a) Its core begins fusing iron. (b) Its supply of hydrogen is used up. (c) The carbon core detonates, and it explodes as a Type I supernova. (d) Helium builds up in the core, while the hydrogen-burning shell expands. (e) The core loses all of its neutrinos, so all fusion ceases.

Answer 47

(d) Helium builds up in the core, while the hydrogen-burning shell expands.

Question 48

What determines the outcome (bang or whimper) is

Answer 48

the mass of the star when it is ready to die, not the mass it was born with.

Question 49

do black dwarfs exist?

Answer 49

No

Question 50

Stars like our Sun will end their lives as

Answer 50

white dwarfs

Question 51

a one-time violent explosion – once it happens, there is little or nothing left of the progenitor star.

Answer 51

supernova

Question 52

Star that flares up very suddenly and then returns slowly to its former luminosity

Answer 52

novae

Question 53

A white dwarf can explode when

Answer 53

Its mass exceeds the Chandrasekhar limit.

Question 54

star formation is

Answer 54

cyclical