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Astronomy > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

The hottest zone in the sun is the

A

core

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2
Q

The most common element in the sun is

A

hydrogen

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3
Q

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

A

True

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4
Q

The innermost part of the sun is the

A

core

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5
Q

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

A

radiative zone

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6
Q

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 ______________.

A

convective zone

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7
Q

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

A

photosphere

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8
Q

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

A

chromosphere

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9
Q

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

A

corona

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10
Q

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

A

number of solar flares
number of sunspots
aurora on Earth

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11
Q

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

A

M

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12
Q

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

A

True

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13
Q

Astronomers use the term interstellar matter to refer to:

A

gas and dust that lies between stars 

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14
Q

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

A

hydrogen

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15
Q

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

A

a globular star cluster 

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16
Q

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

A

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

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17
Q

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

A

white dwarf 

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18
Q

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

A

in giant molecular clouds

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19
Q

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

A

to the left 

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20
Q

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

A

when nuclear fusion reactions begin inside its core 

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21
Q

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

A

Temperature
* Mass
* Energy emission
* Composition
* Etc.

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22
Q

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

A

luminosity

23
Q

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

A

apparent brightness

24
Q

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

A

a lower luminosity

25
Q

formula for apparent brightness

A

luminosity / distance^2

26
Q

brightest stars are what magnitude

A

1

27
Q

faintest stars are what magnitude

A

6

28
Q

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

A

distance and apparent brightness

29
Q

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

A

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

30
Q

The more massive stars are generally also the more

A

luminous

31
Q

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

A

E. All of the Above

32
Q

where most stars are

A

the main sequence

33
Q

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

A

luminosity and surface temperature

34
Q

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

A

parallax

35
Q

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

A

light curve

36
Q

The interstellar medium consists of

A

gas and dust

37
Q

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

A

nebula

38
Q

glowing cloud of hot interstellar medium

A

emission nebula

39
Q

Study of the stars and galaxies through hydrogen signals

A

radio astronomy

40
Q

The reddish color of emission nebulae indicates that:

A

hydrogen gas is present

41
Q

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

A

Gravitational

42
Q

Objects more massive than the Sun form into stars

A

Much faster, over tens of thousands of years

43
Q

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

A

globular cluster

44
Q

What is a T-Tauri star?

A

A protostar about to become a star

45
Q

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

A

the conversion of hydrogen to helium

46
Q

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

A

helium flash

47
Q

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.

A

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

48
Q

What determines the outcome
(bang or whimper) is

A

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

49
Q

do black dwarfs exist?

A

No

50
Q

Stars like our Sun will end their lives as

A

white dwarfs

51
Q

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

A

supernova

52
Q

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

A

novae

53
Q

A white dwarf can explode when

A

Its mass exceeds the Chandrasekhar limit.

54
Q

star formation is

A

cyclical

Astronomy (2 decks)

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