Unit E Section 1.3

Question 1

WHAT IS A STAR?

Answer 1

A star is a hot, glowing ball of gas (main hydrogen) that gives off tremendous light energy

Question 2

What is the weight of the Sun compared to Earth?

Answer 2

Our Sun has a mass 300 000 times greater than Earth, with an average density of 1.4 times that of water.

Question 3

What is the size and weight of the Betelgeuse compared to the sun?

Answer 3

In diameter, Betelgeuse is 670 times larger than our Sun but only 1/10-millionth as dense

Question 4

What does the color of the star depend on?

Answer 4

The color of a star depends on its surface

temperature.

Question 5

What do hot stars look like?

Answer 5

Very hot stars look blue

Question 6

What do cooler stars look like?

Answer 6

Cooler stars look red.

Question 7

What is the “Hertzsprung-Russell diagram”?

Answer 7

Shows the stars fall into several distinct groupings

Question 8

Which star grouping does the sun belong to?

Answer 8

Main sequence

Question 9

How much percent of stars fall into the main

sequence?

Answer 9

Ninety percent of

all stars fit into this grouping.

Question 10

What do nebulae mean?

Answer 10

Stars form in regions of space where there are huge

accumulations of gas and dust called nebulae

Question 11

What gases are nebulae formed of?

Answer 11

75% hydrogen

23% helium

The other 2% is oxygen, nitrogen,
carbon, and silicate dust

Question 12

What is interstellar matter

Answer 12

is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays

Question 13

What is protostar?

Answer 13

the first stage in a star’s formation

Question 14

What is fusion?

Answer 14

This process, known as fusion, releases great quantities of energy and radiation.

Question 15

What does the star depend on to figure out if it is a Sun-like or massive?

Answer 15

Depending on the mass of the star formed from a particular nebula,

Question 16

What do Sun-like (in terms of mass) or massive spend most of their lives doing?

Answer 16

Both types of stars spend most of their lives in this main sequence, converting hydrogen to helium in their cores.

Question 17

What makes the stars in a stable state?

Answer 17

The outward pressure of radiation on the stellar

material is counteracted by gravity

Question 18

When does the stable state of the star shrink?

Answer 18

-When the hydrogen in the core has been used up, the stable state star shrinks in size, heating the helium core so that it first starts fusing to carbon, then to other elements

Question 19

How does a star become a red giant or a red supergiant?

Answer 19

• After the stable state, when hydrogen is used up and turns into other elements,
• As gravity causes the star to contract, further nuclear reactions occur, leading to expansion of the outer layers.

Question 20

What is the difference between a red giant and a red supergiant?

Answer 20

• red giant if it is a Sun-like star

- red supergiant if it is a massive star

Question 21

When will our sun become a red giant?

Answer 21

• Our Sun will become a red giant in about 5 billion years.

- At that time, the Sun’s diameter may extend out past the present orbit of Mars.

Question 22

When does the final stage in a star’s life occur?

Answer 22

when the fusion reaction stops

Question 23

When does the fusion reaction end for a Sun-like star?

Answer 23

-fusion ends when the core temperature in the star is
no longer hot enough to keep the reaction going.

-With no heat input from fusion, the decreasing pressure is unable to prevent gravity from causing the star to collapse slowly on itself

Question 24

What happens to a sun-like star after its last stage occurs as a giant red star

Answer 24

The Sun-like star continues to shrink, gradually becoming a WHITE DWARF, no larger than Earth

Eventually, the star will fade completely until it evolves into a cold, dark BLACK DWARF?

Question 25

When does the fusion reaction stop in a massive star?

Answer 25

• when the star runs out of fuel.
• The lack of heat input into the core from fusion enables gravity to get the upper hand.

-Gravity causes the star’s core to collapse
rapidly on itself

• The collapse ends suddenly with an outgoing shock
  wave. This, in turn, causes the outer part of the star to explode in a catastrophic event is known as a supernova

Question 26

What is a supernova?

Answer 26

This, in turn, causes the outer part of the (massive) star to explode in a catastrophic event is known as a supernova

Question 27

What happens if a massive star is not completely destroyed by the explosion?

Answer 27

the core is left as a neutron star or a black hole.

Question 28

what is a neutron star?

Answer 28

A neutron star is a rapidly spinning object only about 30 km in diameter.

Question 29

What is a black hole?

Answer 29

A black hole is a highly dense remnant of a star in which gravity is so strong that not even light from the radiation going on inside the remnant can escape.

Question 30

Black holes are themselves invisible to telescopes. Astronomers only know about their existence indirectly because of how material near a black hole becomes very hot and bright.

Answer 30

Occasionally, massive stars collapse on themselves with such violence that they become super-dense. The gravity around these bodies is so intense that even light cannot escape being pulled inward. These bodies are called black holes.

Question 31

Are humans stardust?

Answer 31

Humans are carbon-based life forms. The carbon making up our bodies was created inside ancient stars that exploded, distributing their elements in our region of the galaxy

Question 32

What are Constellations?

Answer 32

are the groupings of stars we see as patterns in the night sky

Question 33

How many Constellations are there?

Answer 33

88 constellations recognized by the International

Astronomical Union

Question 34

What are asterisms?

Answer 34

many unofficially recognized star

groupings

Question 35

What is one of the most famous asterisms visible

from the northern hemisphere?

Answer 35

the Big Dipper, which is part of the constellation Ursa Major.

-The ancient Greeks saw the stars that make up Ursa Major as a bear.

-The early Black Foot nation of North America also
saw a bear.

-Ancient Europeans saw a variety of different patterns
including a chariot, a wagon, and a plow

Question 36

Orion Constellation/

Answer 36

The constellation of Orion, a figure in Greek mythology who was thought of as a great hunter

Question 37

What is a galaxy?

Answer 37

A galaxy is a grouping of millions or billions of stars, gas, and dust. It is held together by gravity.

Question 38

What is the galaxy we live in?

Answer 38

The galaxy we live in is a spiral galaxy called the Milky Way

It is shaped like a flattened pinwheel, with arms spiraling out from the center

Question 39

What are the two other main types of galaxies?

Answer 39

elliptical and irregular

Question 40

elliptical galaxy

Answer 40

An elliptical galaxy has a shape similar to that of a football or egg and is made up mostly of old stars.

Question 41

irregular galaxy

Answer 41

An irregular galaxy has no notable shape and tends to be smaller than the other two galaxy types.

A mixture of old and young stars are found in irregular
galaxies.