Astronomy Test 3

Question 1

When would the star reach the point of blowing themselves apart?

Answer 1

When a star’s mass (150 times our sun) is too great it generates so much power that it blows itself up.

Question 2

What does it mean when a star is more luminous than another?

Answer 2

When a star is more luminous it means that it is either more massive and/or hotter in temperature.

Question 3

What are brown dwarfs?

Answer 3

Smaller “failed stars” that can be found in the lower right hand corner of the HR diagram

Question 4

When would a star fall of the main sequence?

Answer 4

A star falls off the main sequence when hydrogen fuses in the core of the star

Question 5

What happens after hydrogen has completely stopped fusion in the core?

Answer 5

After hydrogen fusion has stopped the star will begin to heat up and expand

Question 6

What is a product of helium fusion?

Answer 6

Carbon is a product of helium fusion

Question 7

How does a red giant change near the end of its life?

Answer 7

A red star will become cooler and brighter as it evolves

Question 8

What do we call the expanding shell of gas that is the remnant of a low-mass star?

Answer 8

The expanding shell of gas left from a low-mass star is called a planetary nebula

Question 9

What is the last element found at a star’s core that cannot release energy either through fusion or fission?

Answer 9

Iron is the last element found at a star’s core when going through fusion

Question 10

What can be found at the core of a planetary nebula?

Answer 10

White dwarves are found at the core of planetary nebula

Question 11

What are the stages of a high mass and low mass star?

Answer 11

The stages of life for a star are:
Protostar, main-sequence, white dwarf, red giant >(high mass) supernova, neutron star or black hole

Question 12

What causes a black hole?

Answer 12

Black holes from when the gravity of a massive star overcomes neutron degeneracy pressure and the core collapses

Question 13

What is a possible result of a white dwarf gaining mass due to the accretion in a binary system?

Answer 13

The white dwarf will reach the limit it can of mass and collapse, leading to a supernova

Question 14

What are some key things to know about novae?

Answer 14

-A star system that undergoes a nova may have another nova in the future
-A nova involves fusion taking place on the surface of a white dwarf
-When a star system undergoes a nova, it brightens considerably, but not as much as a star system undergoing a supernova
-The word nova means “new star” and originally referred to stars that suddenly appeared in the sky, then disappeared again after a few weeks

Question 15

Where does hydrogen burn after the star has become a red giant?

Answer 15

Hydrogen will burn in only shells outside the core of a star after it becomes a red giant

Question 16

What size is comparable to a white dwarf?

Answer 16

A white dwarf is comparable in size to the Earth

Question 17

What is a pulsar and how does it appear?

Answer 17

A pulsar is a rapidly rotating neutron star that emits flashes of light several times per second with perfect regularity

Question 18

When light appears red shifted what can we assume?

Answer 18

When light is red shifted we can assume that the light is coming from a compact, massive object (heavy gravity)

Question 19

What is important to know about black holes?

Answer 19

-A black hole is any object from which the escape velocity equals the speed of light.
-Nothing is able to escape from inside the event horizon of a black hole
-If someone was to fall into a black hole you will never see them cross the event horizon, but they will appear more and more red shifted
-If we watch a clock fall towards a black hole, we will see it tick slower and slower
-If you fell into a black hole, you would experience time to be running normally as you plunged rapidly across the event horizon
-The singularity of a black hole is the center of the black hole

Question 20

True or false: after several billion years a white dwarf is what will be left of our solar system?

Answer 20

True. After several billion years we would see a white dwarf as what is left of our solar system

Question 21

How big is our milky way? (the disk)

Answer 21

The milky way is 100,000 light years in diameter

Question 22

Where would we find globular clusters?

Answer 22

Globular clusters can be found in the halo of our galaxy

Question 23

What can be found in the disk of our galaxy?

Answer 23

Some things that can be found in the disk are: open clusters, gas and dust, O and B stars, old K and M stars

Question 24

What is the interstellar medium?

Answer 24

Interstellar medium is the space in between star systems and is made of mostly gas and dust

Question 25

Where are elements past hydrogen and helium made?

Answer 25

Elements past hydrogen and helium would be found in stars or super novea where fusion is taking place

Question 26

What proof do we have of dark matter?

Answer 26

We know there is dark matter in the galaxy because of stars orbital speeds away from the galactic center are showing a gravitational pull

Question 27

How long does it take the sun to orbit the milky way galaxy?

Answer 27

It takes 230 million years for the sun to orbit the milky way galaxy

Question 28

Do halo stars have rocky planets around them?

Answer 28

No, halo stars do not have rocky planets around them because there is not enough heavy elements is the area to form them

Question 29

In what zodiac constellation is our galactic center (black hole) found?

Answer 29

Our galactic center can be found in the constellation Sagittarius

Question 30

What is special about the spiral arms in the milky way galaxy?

Answer 30

In the spiral arms of the galaxy star formation is happening

Question 31

True or false: Our galaxy is the most common type of galaxy for larger galaxies?

Answer 31

True: most large galaxies are spiral galaxies they are also most commonly found in large clusters

Question 32

How do we know there’s a black hole at the center of our galaxy?

Answer 32

We know there’s a black hole at the center because of the motion of stars indicating a million solar masses within a small region (1 parsec across)

Question 33

What is special about elliptical galaxies?

Answer 33

Elliptical galaxies appear reddest in color

Question 34

What does hubble’s law teach us?

Answer 34

Hubble’s law teaches us that the more distant a galaxy is from us, the faster it moves away from us

Question 35

How did Hubble discover the expansion of the universe?

Answer 35

He plotted velocity and distance against each other

Question 36

Fill in the blank: the faster a spiral galaxy’s rotation speed, the more ______ it is

Answer 36

The faster a spiral galaxy’s rotation speed, the more luminous it is according to the tully-fisher relation

Question 37

Why is stellar parallax so important?

Answer 37

Stellar parallax is the most accurate way to determine the distance to a nearby star In order here is the best way to determine distance (nearest to furthest) Parallax, main-sequence fitting, cepheid variables, white-dwarf supernovae, hubble’s law

Question 38

Can we see past the cosmological horizon?

Answer 38

No, we cannot see past the cosmological horizon because that would mean we are looking past when the universe formed

Question 39

When something is further away is it more red-shifted or blue-shifted?

Answer 39

The further something is the more red-shifted it becomes

Question 40

What three elements are skipped during the triple alpha process?

Answer 40

Lithium, beryllium, and boron are usually skipped in the conversion of helium into carbon through the triple alpha process