Astro 7N Unit 3 and 4 Test

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

Fill in the blank in the following chemical reaction that occurs in the Sun:
Hydrogen-2 + proton = _____ + energy:

Answer 4

Helium-3

Question 5

Which has the smallest radius?

Answer 5

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?

Answer 7

main sequence star with surface temperature 20000 K

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 supergiants 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

the 2 solar mass main sequence star appears brighter

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

Question13

What is the exoplanet’s orbital period, and the percent brightness drop in light, for
the case in the image above from the Kepler Exoplanet Transit Hunt activity?

Answer 13

5 days and 0.30 %

Question 14

How do astronomers measure the temperature of stars?

Answer 14

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

Question 15

Question 15

In the inverse square law activity above, what would the wattage of the top
lightbulb need to be, such that it appeared as bright as the bottom lightbulb which
is a 25-Watt bulb?

Answer 15

100 Watts

Question 16

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

Answer 16

red main sequence stars

Question 17

Question 17

Which of the stars, in the diagram above, is the hottest?

Answer 17

D (most far left and highest)

Question 18

Question 18

If they were all formed at the same time, which of the stars in the diagram above
will live the longest?

Answer 18

B (farthest right and lowest)

Question 19

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

Answer 19

50 parsecs

Question 20

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

Answer 20

stellar nursery, protostar, blue star on main sequence, Type II supernova, black hole

Question 21

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

Answer 21

Star A is 3 times farther away than Star B

Question 22

Question 22

In the p-p chain, shown in the above diagram, what particles must be input in order to produce one 4He nucleus?

Answer 22

6 protons, but 2 of them are returned when the 4He is produced

Question 23

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

Answer 23

chromosphere

Question 24

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 24

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

Question 25

If the entire mass of Earth were concentrated in a region the size of a marble, the resulting object would be ..

Answer 25

a black hole

Question 26

Which is the smallest object?

Answer 26

a neutron star

Question 27

A galaxy has an H-alpha emission line observed at a wavelength 10 percent larger than the rest wavelength of H-alpha. What is the redshift of the galaxy?

Answer 27

0.1

Question 28

Question 28

What is in this image?

Answer 28

supernova remnant (check study guide)

Question 29

Which is the most luminous?

Answer 29

quasar

Question 30

Which contains the most stars?

Answer 30

a spiral galaxy

Question 31

Galaxy A appears twice the angular size of Galaxy B. Assuming the two galaxies have the same physical size in kiloparsecs, which of the following is true?

Answer 31

Galaxy B is 2 times farther away than Galaxy A

Question 32

What fundamental particles make up a Helium-3 atom?

Answer 32

5 up quarks, 4 down quarks, 2 electrons

Question 33

Check 33 on study guide

Question 34

Which statement is FALSE about planetary nebulae?

Answer 34

planetary nebulae usually have black holes at their centers

Question 35

Which statement is TRUE about stars?

Answer 35

Stars form in molecular clouds, where temperatures are about 10 Kelvin.

Question 36

How tiny a spot is the Hubble Deep Field?

Answer 36

the size of President Roosevelt’s eye on a dime held at arm’s length

Question 37

What is the last thing that happens in the history of the Universe?

Answer 37

electrons join with nuclei to make atoms

Question 38

If a galaxy had no dark matter, we would observe ..

Answer 38

the rotation velocity would decrease with increasing distance like the Keplerian curve in our Solar System

Question 39

How many times bigger is the Local Group of galaxies in which the Milky Way resides than the Milky Way itself?

Answer 39

about 100 times bigger

Question 40

Which one of the following is FALSE about galaxy collisions?

Answer 40

Galaxy collisions destroy most of the stars in the galaxies involved

Question 41

If a galaxy is moving away from us the wavelength of the light it emits will be ..

Answer 41

increased

Question 42

The stars in the halo of our Milky Way Galaxy are ..

Answer 42

older and redder than those in the disk

Question 43

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

Answer 43

4 million solar masses

Question 44

Question 44

Question 45

Which force has the photon as its boson

Answer 45

electromagnetic

Question 46

Which mysterious phenomena do scientists attribute to dark energy?

Answer 46

The increasing rate of expansion of the Universe.

Question 47

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

Answer 47

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

Question 48

What are the “standard candles” that were used to determine the Universe is accelerating?

Answer 48

Type Ia supernovae

Question 49

An older star cluster ..

Answer 49

has a main sequence turnoff farther to the right on the H-R diagram.

Question 50

Which of the following statements is TRUE about Supernovae?

Answer 50

Type II supernovae are produced by the death of a massive star

Question 51

Which of the following does physics professor Bernard Bates assert as essential in order for living organisms to develop advanced technology?

Answer 51

living on land

Question 52

If you 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 52

carbon dioxide

Question 53

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

Answer 53

octopus

Question 54

What are the three primary colors of light, and what happens when they are combined?

Answer 54

Red, green, and blue are the primary colors and they can be combined in different proportions to make any color of light that is visible to the eye

Question 55

When red, green, and blue light are combined in equal proportions the result is?

Answer 55

white light

Question 56

Light of different colors is emitted from different stars because ..

Answer 56

The stars have different temperatures, with redder stars being cooler than bluer stars.

Question 57

The degree of purity of a color (with 0% being black) is called its ..

Answer 57

saturation

Question 58

If the hue of red light is 0 degrees, then the hue of green light would be .

Answer 58

120 degrees because it is separated by that many degrees on the color wheel

Question 59

In subtractive color mixing, like with ink on paper, when all three primary colors are combined the result is ..

Answer 59

black / dark color

Question 60

What kind of cells in the human eye perceive color?

Answer 60

cones

Question 61

What secondary color is made by mixing red and green in the “RGB” additive-color scheme for light?

Answer 61

yellow

Question 62

What is the name for colors opposite each other (180 degrees apart) on the color wheel?

Answer 62

Complementary colors