Module 2 Lesson 2

Question 1

what is and hr diagram?

Answer 1

HR diagrams combine information about temperature, colour, size and luminosity.

Question 2

Compare and contrast absolute magnitude and apparent magnitude, luminosity, spectrum.

Answer 2

differences:
Luminosity- total amount of energy a star radiates per second.

apparent magnitude- the brightness of a star as it APPEARS to us

Absolute magnitude- the ACTUAL amount of light given off by a star at a standard distance

Light spectrum is the many different wavelengths of energy produced by a light source. (eg: star)

similarties:

all of this releates to light

Question 3

Describe how stars evolve and what happens when they die

Answer 3

stars evolve due to fusion. the star collapses when the gravity exceeds pressure, the star expands when pressure overcomes gravity. this causes the stars to evolve.

low mass stars become white dwarfs then black dwarfs when they die

intermediate mass stars become red giants, white dwarfs then black dwarfs when they die

high mass stars become supernova and then either a black hole or a neutron star

Question 4

what is a super nova. how and when does a super nova occur?

Answer 4

it is the explosion of a star.

When the pressure drops low enough in a massive star, gravity suddenly takes over and the star collapses

Question 5

what is a red dwarf

Answer 5

a red dwarf is the smallest and coolest star on the main sequence

Question 6

what is a black hole? when and how does it occur?

Answer 6

A black hole is a place in space where gravity pulls so much that even light can not get out.

A black hole can be formed by the death of a massive star.

When such a star has exhausted its fuels in its core. the core becomes unstable and gravitationally collapses inward upon itself which forms a black hole

Question 7

what is a white dwarf

Answer 7

A white dwarf is what stars become after they have exhausted their nuclear fuel

Question 8

what is a nebula

Answer 8

A nebula is an enormous cloud of dust and gas. (it is what creates new stars)

Question 9

what is a planetary nebula

Answer 9

it sheds its outer layers, which form a beautiful cloud called a “planetary nebula”, while the dying star’s core becomes a white dwarf.

(large stars a planetary nebula when dying not small stars)

Question 10

what is a main sequence star

Answer 10

Main sequence stars are stars that are fusing hydrogen atoms to form helium atoms in their cores.

Question 11

How do the stars’ luminosity compare with their radii?

Answer 11

stars with a larger radius have a higher luminosity

Question 12

how does a stars radii compare with their mass?

Answer 12

as the radius increases the mass increases

Question 13

Why would the size of a star affect its luminosity?

Answer 13

As the size of a star increases, luminosity increases. If you think about it, a larger star has more surface area. That increased surface area allows more light and energy to be given off.

Question 14

what are the different star groups?

Answer 14

white dwarfs, main sequence, supergiants and giants

Question 15

what is the temperature of a blue and red star

Answer 15

blue stars are hotter

red stars are cooler

Question 16

look at hr diagram

Answer 16

look at hr diagram

Question 17

why do some stars appear brighter and others do not?

Answer 17

stars may appear brighter because they may be closer to earth or they may be larger

Question 18

what is luminosity

Answer 18

Luminosity- total amount of energy a star radiates per second.

Question 19

what is apparent magnitude?

Answer 19

Apparent magnitude- the brightness of a star as it APPEARS to us

Question 20

what is absolute magnitude?

Answer 20

Absolute magnitude- the ACTUAL amount of light given off by a star at a standard distance

Eg. If all stars were the same distance from earth, the sun would not be brightest.

Question 21

explain the life cycle of a small to medium star

Answer 21

there are clouds of dust and gas and if it is big enough its own gravity will start to collapes so it folds in on itself toward the center of the cloud which causes the center of the cloud to become denser, hotter. eventually the particles of the gas and dust are made of are brought close to each other which causes them to fuse.

inside every newborn star hydrogen atoms fuse together to make a helium. the process is known as (fusion). fusion creates the energy for every star

the main sequence is red dwarf.

at some point hydrogen runs out. the core of the star will start to collapes on its self under its own weight. which leads to only the star to be left with its core. which is called a white dwarf

white dwarf will cool down to become a black dwarf

birth and early life: protostar and nebula

main sequence: red dwarf

old age: white dwarf

death: black dwarf
remains: black dwarf

Question 22

explain the life cycle of a large star

Answer 22

there are clouds of dust and gas and if it is big enough its own gravity will start to collapes so it folds in on itself toward the center of the cloud which causes the center of the cloud to become denser, hotter. eventually the particles of the gas and dust are made of are brought close to each other which causes them to fuse.

inside every newborn star hydrogen atoms fuse together to make a helium. the process is known as (fusion). fusion creates the energy for every star.

for the main sequence of a large star it becomes yellow/orange

at some point hydrogen runs out. the core of the star will start to collapes on its self under its own weight and becomes more denser and hotter

when stars fuse helium it creates more eneergy. that causes the outer layers of the star to expand. the sun will grow so large it will become a red giant. soon the outer layers will drift away which forms a planetary nebula

this cauuses the star to be left with only its core which is called the white dwarf.

white dwarf will cool down to become a black dwarf

birth and early life: protostar and nebula

main sequence: yellow/orange stars.

old age: red giant

death: white dwarf
remains: black dwarf

Question 23

explain the life cycle of a giant star

Answer 23

there are clouds of dust and gas and if it is big enough its own gravity will start to collapes so it folds in on itself toward the center of the cloud which causes the center of the cloud to become denser, hotter. eventually the particles of the gas and dust are made of are brought close to each other which causes them to fuse.

inside every newborn star hydrogen atoms fuse together to make a helium. the process is known as (fusion). fusion creates the energy for every star.

the main sequence of a giant star is blue.

then because the star is so big it is able to fuse heavier elements inside its core. once it reaches its limite the core starts to collapse. this creates the super giant which then leads to a huge shock wave which causes a super nova explosion.

after the star becomes either a balck hole or a neutron star

birth and early life: protostar and nebula

main sequence: blue stars, big, hot and bright

old age: super giant

death: super nova
remains: black hole or neutron star

Question 24

REMINDER: measurements

Answer 24

temperature is measured in K.

Luminosity is measured in suns

radius is measured in suns