Module 5 - 5.5.1 Stars

Question 1

Planets (definition)

Answer 1

Bodies that move in circular/elliptical orbits around a star

Question 2

Planetary Satellites (definition)

Answer 2

Bodies that orbit planets

Question 3

Comets (definition)

Answer 3

Large, rocky balls of ice that travel in highly elliptical orbits around stars

Question 4

Solar Systems (definition)

Answer 4

A collection of planets, their moons and smaller bodies (asteroids, meteoroids and comets) that orbit around a star

Question 5

Galaxies (definition)

Answer 5

Clusters of many billions of stars held together by gravity

Question 6

The Universe (definition)

Answer 6

All existing matter and space considered as a whole

Question 7

The Universe is

Answer 7

expanding

Question 8

The further galaxies are apart from one another

Answer 8

the faster they will move apart

Question 9

Stars in a galxy rotate around

Answer 9

the galaxy’s centre of mass

Question 10

Planets are formed when

Answer 10

interstellar dust is attracted into larger clumps

Question 11

Comets
- orbit around
- come from

Answer 11

• stars from very far away
• a more distant place called the Oort Cloud

Question 12

Low Mass Stars: mass between
High Mass Stars: mass between

Answer 12

• 0.5MSun and 10MSun
• > 10MSun

Question 13

Life Cycle Route of a Low Mass Star

Answer 13

• stellar nebula
• protostar
• main sequence star
• red giant star
• planetary nebula
• white dwarf
• black dwarf

Question 14

Life Cycle Route of a High Mass Star

Answer 14

• stellar nebula
• protostar
• main sequence star
• red super giant
• supernova
• neutron star or black hole

Question 15

Nebulae (definition)

Answer 15

Giant clouds of hydrogen gas and interstellar dust that stars are formed from

Question 16

The higher the mass of a main sequence star (3)

Answer 16

• the shorter a life they have
• the less time they spend on this stage
• have more fuel but use it up faster

Question 17

Pulsars (4)

Answer 17

• neutron stars with a large magnetic field
• rotate rapidly
• emit highly directional bursts of em radiation
• frequency of the radiation is assumed to be the rate at which the star and its magnetic field rotates

Question 18

A Singularity (definition)

Answer 18

A theoretical point at which matter is compressed to an infinitely small and dense point and the law of physics as we know them break down

Question 19

Electron Degeneracy Pressure (definition)

Answer 19

The pressure that stops the gravitational collapse of a low mass star

Question 20

Electron Degeneracy Pressure (process) (4)

Answer 20

• when matter is compressed into a very small volume, electrons are no longer free to move between energy levels
• as core contracts, compression forces electrons into higher energy levels since they have nowhere else to go
• this rush of electrons finding an available space creates a pressure called the Electron Degeneracy Pressure
• results in an outward acting force

Question 21

Electron Degeneracy Pressure Appears at which stage in the life cycle of a star (2)

Answer 21

• prevents further collapse so results in a stable while dwarf star
• Electron Degeneracy Pressure balances inwards gravitational force

Question 22

The luminosity of a star is (definition)

Answer 22

the total energy the star emits per second

Question 23

The Hertzsprung Russel diagram shows (2) (y and x axis)

Answer 23

• the positions of stars on a scatter graph
• based on their luminosities and temperatures
• y axis: increasing luminosity
• x axis: decreasing temperature

Question 24

The Hertzsprung Russel diagram shows that for main sequence stars

Answer 24

their luminosity increases with surface temperature