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astro7n > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

A high luminosity star…

A

emits more light than a low-luminosity star

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2
Q

If a red giant appears the same brightness as a red main sequence star, which one is farther away?

A

the red giant

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3
Q

The heaviest nuclei of all are formed….

A

During a supernova explosion

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4
Q

Hydrogen -2 + proton = _______ + energy

A

Hydrogen-3

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5
Q

Which of the following has the smallest radius?

A: type A main sequence star 
B: main sequence star with surface temperature 8000 K 
C: type K main sequence star 
D: white dwarf 
E: neutron star
A

E. Neutron star

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6
Q

Why does the main sequence part of a star’s life end?

A

The Hydrogen in the core is exhausted

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7
Q

Which of the following will have the shortest lifetime on the main sequence?

A: main sequence star with surface temperature 20000 K
B: main sequence star with surface temperature 3000 K
C: main sequence star with luminosity one tenth that of the Sun
D: the Sun
E: main sequence star with mass 2 times the Sun’s

A

main sequence star with surface temperature 20000K

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8
Q

Many of the brightest 100 stars viewed from Earth are not on the main sequence (even though most stars are) because….

A

The most luminous stars are giants and supergiant’s that have already finished their main sequence lifetimes.

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9
Q

A 2-solar-mass main sequence star is at the same distance as a 0.2-solar-mass main sequence star. Which star appears brighter?

A

A : depends on the phase of the Moon
➔ B: the 2 solar mass main sequence star appears brighter
C: the stars are approximately the same brightness
D: the 0.2 solar mass main sequence star appears brighter
E: we cannot tell with the information given

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10
Q

The temperature of the photosphere of the Sun is closest to….

A

6000 Kelvin

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11
Q

An estimate of the number of communicating/technological civilizations that we expect in our galaxy would be a larger number if….

A

The average number of planets that could support life for each star were larger

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12
Q

If the Sun had twice its mass, then which of these planets would be in its habitable zone?

A

Jupiter

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13
Q

How do astronomers measure the temperature of stars?

A

By looking at which absorption lines are present in the star’s spectrum

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14
Q

The largest fraction of nearby stars (e.g. within 100 light years) are…

A

red main sequence

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15
Q

The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the distance to the star?

A

50 parsecs

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16
Q

Which of the following is the sequence of events for a 40-solar mass star (one of the most-massive stars)?

A

Stellar nursery, protostar, blue star main sequence, Type II supernova, black hole.

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17
Q

Star A is 9 times as luminous as Star B. The two stars appear the same brightness. What is true about their distance?

A

Star A is 3 times farther away than star B

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18
Q

Which of the following do several contributions in your reading articles is a good model of an intelligent “alien” species already living on earth?

A

Octopus

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19
Q

The corona of the Sun:

A

is visible during a solar eclipse

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20
Q

What is the name of the slightly cooler layer of the Sun just outside the photosphere?

A

corona

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21
Q

How does a star move on the H-R diagram during the period of time it is converting hydrogen to helium in its core?

A

It remains nearly fixed at a certain point on the main sequence and does not move on the H-R diagram.

22
Q

How many protons does a Hydrogen atom have?

A

1 proton, and the different forms can have 1 or 2 neutrons

23
Q

In the transit method of finding extrasolar planets, the distance of the planet from its star is found from:

A

Kepler’s 3rd Law using the period of the planets orbit (how often a transit occurs)

24
Q

Which of the following is true?

A

Habitable planets have been found around red dwarfs as well as around sun-like stars.

25
Q 
Order the following object from small to large:
the Sun
black hole
neutron star
white dwarf
A

small: black hole, neutron star, white dwarf, the Sun :Large

26
Q

What type of life found on earth, could survive in the clouds of Venus?

A

Acidophiles

27
Q

Star A is four times further away from the Sun than Star B. The parallax angle of Star B is:

A

FOUR TIMES LARGER than that of Star A

28
Q

Stars that include Mercury in their habitable zone are

A

About half the mass of the sun

29
Q

The sequence of events for the Sun-like star is

A

Stellar nursery, protostar, sun-like star on main sequence, red giant, planetary nebula, white dwarf.

30
Q

What is the heaviest chemical element produced in the core of any star?

A

Iron

31
Q

How many times bigger are galaxy lusters than individual galaxies?

A

Hundreds of times bigger

32
Q

True statement: Stars form in molecular clouds, where temperature are about 10 degrees Kelvin.

A

False statements …

33
Q

If I wanted to design a form of animal life capable of living on the very young Earth (about 4 billion years ago), which of these gases would at that time be most plentiful for it to breathe?

A

Carbon dioxide

34
Q

The supermassive black hole in the center of the Milky Way has a mass of

A

4 million solar masses

35
Q

Why can’t we see back the whole way to the time the Big Bang expansion began?

A

The radiation scatters off matter frequently so the Universe is opaque.

36
Q

Which of the following main-sequence turnoffs indicates the oldest globular cluster?

A

K5

37
Q

Roughly how many stars are in the Milky Way Galaxy?

A

400 billion

38
Q

The open clusters were a population of relatively young stars, so where would you expect to see them from here?

A

In the disk

39
Q

Which force has the gluon as its boson?

A

Strong

40
Q

True Statement: There is no center in the universe

A
41
Q

Compared to spiral galaxies, elliptical galaxes have

A

less gas, redder colors, and less new star formation

42
Q

The redshifts of galaxies are found to be larger for

A

Galaxies that are further away

43
Q

Which of the following is not true about dark matter?

A

Dark matter and dark energy are two aspects of the same phenomenon

44
Q

What fundamental particles make a Helium-3 atom?

A

5 up quarks, 4 down quarks, 2 electrons

45
Q

How many up and down quarks make up a proton?

A

two ups, one down

46
Q

What combined with what right before the universe became transparent?

A

Electrons combined with Hydrogen - 1 nuclei and with Helium-4 nuclei

47
Q

How many stars are there in a normal-sized galaxy like the Milky Way?

A

1 billion to 100 billion

48
Q

When will the Milky Way and the Andromeda galaxy collide?

A

In about 5 billion years

49
Q

Extreme environments on Earth are found to have life. Which other Solar System environment COULD NOT have life?

A

Atmosphere of the Sun

50
Q

What is one way the concentric rings of the Cat’s Eye Nebula might have formed?

A

The gas might have been ejected in pulses

astro7n (2 decks)

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