Exam 2

Question 1

A high luminosity star…

Answer 1

emits more light than a low-luminosity star

Question 2

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

Answer 2

the red giant

Question 3

The heaviest nuclei of all are formed….

Answer 3

During a supernova explosion

Question 4

Hydrogen -2 + proton = _______ + energy

Answer 4

Hydrogen-3

Question 5

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

Answer 5

E. Neutron star

Question 6

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

Answer 6

The Hydrogen in the core is exhausted

Question 7

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

Answer 7

main sequence star with surface temperature 20000K

Question 8

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

Answer 8

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

Question 9

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?

Answer 9

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

Question 10

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

Answer 10

6000 Kelvin

Question 11

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

Answer 11

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

Question 12

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

Answer 12

Jupiter

Question 13

How do astronomers measure the temperature of stars?

Answer 13

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

Question 14

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

Answer 14

red main sequence

Question 15

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

Answer 15

50 parsecs

Question 16

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

Answer 16

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

Question 17

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

Answer 17

Star A is 3 times farther away than star B

Question 18

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

Answer 18

Octopus

Question 19

The corona of the Sun:

Answer 19

is visible during a solar eclipse

Question 20

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

Answer 20

corona

Question 21

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

Answer 21

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

Question 22

How many protons does a Hydrogen atom have?

Answer 22

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

Question 23

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

Answer 23

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

Question 24

Which of the following is true?

Answer 24

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

Question 25

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

Answer 25

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

Question 26

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

Answer 26

Acidophiles

Question 27

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

Answer 27

FOUR TIMES LARGER than that of Star A

Question 28

Stars that include Mercury in their habitable zone are

Answer 28

About half the mass of the sun

Question 29

The sequence of events for the Sun-like star is

Answer 29

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

Question 30

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

Answer 30

Iron

Question 31

How many times bigger are galaxy lusters than individual galaxies?

Answer 31

Hundreds of times bigger

Question 32

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

Answer 32

False statements ...

Question 33

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?

Answer 33

Carbon dioxide

Question 34

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

Answer 34

4 million solar masses

Question 35

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

Answer 35

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

Question 36

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

Answer 36

K5

Question 37

Roughly how many stars are in the Milky Way Galaxy?

Answer 37

400 billion

Question 38

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

Answer 38

In the disk

Question 39

Which force has the gluon as its boson?

Answer 39

Strong

Question 40

True Statement: There is no center in the universe

Question 41

Compared to spiral galaxies, elliptical galaxes have

Answer 41

less gas, redder colors, and less new star formation

Question 42

The redshifts of galaxies are found to be larger for

Answer 42

Galaxies that are further away

Question 43

Which of the following is not true about dark matter?

Answer 43

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

Question 44

What fundamental particles make a Helium-3 atom?

Answer 44

5 up quarks, 4 down quarks, 2 electrons

Question 45

How many up and down quarks make up a proton?

Answer 45

two ups, one down

Question 46

What combined with what right before the universe became transparent?

Answer 46

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

Question 47

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

Answer 47

1 billion to 100 billion

Question 48

When will the Milky Way and the Andromeda galaxy collide?

Answer 48

In about 5 billion years

Question 49

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

Answer 49

Atmosphere of the Sun

Question 50

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

Answer 50

The gas might have been ejected in pulses