Stars

Question 1

Interstellar medium

Answer 1

Vast areas of dust and gas between stars and galaxies. 99%gas. It is from this material that new stars are formed. Density and temperature vary

Question 2

Nebulae

Answer 2

Giant clouds of dust and gas (mainly hydrogen) which are the birthplace of stars

Question 3

Protostar

Answer 3

A very hot and dense sphere of condensing dust and gas that is on its way to becoming a star

Question 4

Fusion

Answer 4

A process in which two smaller nuclei join to form a larger nucleus

Question 5

Radiation pressure

Answer 5

Pressure from photons emitted during fusion

Question 6

Gas pressure

Answer 6

Pressure from the nuclei in the core

Question 7

What do radiation and gas pressure do

Answer 7

Maintain the star in equilibrium and balance the force from gravitational attraction. They stop the star from being compressed

Question 8

Main sequence

Answer 8

The stable phase of a stars life

Question 9

Blue giant star

Answer 9

A large powerful, bright star in main sequence

Question 10

Red dwarf star

Answer 10

Small, old, relatively cool star

Question 11

Brown dwarf

Answer 11

Failed star. Fusion in a protostar does not occur and a brown dwarf is created

Question 12

Satellite

Answer 12

A body orbiting around a planet

Question 13

Planets

Answer 13

An object in orbit around a star with a mass large enough for its own gravity to give it a round shape, that undergoes no fusion and has cleared its orbit of most other objects

Question 14

Dwarf planets

Answer 14

A planet that has not cleared its orbit of other objects

Question 15

Asteroids

Answer 15

Objects too small and uneven to be planets. Usually in near - circular orbits around the sun

Question 16

Comets

Answer 16

Small irregular bodies of ice, dust and rock. Highly elliptical orbits

Question 17

Planetary satellites

Answer 17

A body in orbit around a planet like a moon or man made satellites

Question 18

Solar systems

Answer 18

Contain a sun and all the objects that orbit it

Question 19

Galaxies

Answer 19

A collections of stars and interstellar dust and gas. On average contains 100 billion stars

Question 20

Red giants star

Answer 20

An expanding star at the end of is life, with an inert core in which fusion no longer takes place, but in which fusion of lighter elements continues in the shell around the core

Question 21

Red supergiant

Answer 21

A huge star in the last stages of its life before it ‘explodes’ in a supernova

Question 22

White dwarf star

Answer 22

A very sense star formed from the core of a red giant in which no fusion occurs

Question 23

Planetary nebula

Answer 23

The outer layers of a red giant that have drifted into space leaving the hot core behind at the centre as a white dwarf

Question 24

Electron degeneracy pressure

Answer 24

A quantum-mechanical pressure created by the electrons in the core of a collapsing star due to the Pauli exclusion principle

Question 25

Chandrasekhar limit

Answer 25

The mass of a stars core beneath which electron degeneracy pressure is sufficient to prevent gravitational collapse

Question 26

Supernova

Answer 26

The implosion of a red supergiant at the end of its life, which leads to subsequent ejection of stellar matter into space, leaving an inert remnant core

Question 27

Neutron star

Answer 27

The remnant core of a massive star after the star has gone supernova (and if the mass of the core is greater than the Chandrasekhar limit) the core has collapsed under gravity to an extremely high density as it is almost entirely made up of neutrons

Question 28

Neutron degeneracy pressure

Answer 28

The pressure that balances the gravitational force inwards in a neutron star

Question 29

Singularity

Answer 29

In the centre of a black hole there is a gravitational singularity where a huge mass in an infinitely small space is contained and laws of physics do not operate

Question 30

Black hole

Answer 30

The remnant core of a massive star after it has gone supernova and the core has collapsed so far that in order to escape it an object would need an escape velocity greater than the speed of light and therefore nothing, not even photons, can escape it

Question 31

What star mass causes evolution into red giants?

Answer 31

0.5-10 sun masses

Question 32

What star masses cause evolution into red supergiant?

Answer 32

10+ solar masses

Question 33

After supernova what core mass causes a black hole

Answer 33

3 solar masses

Question 34

What value is the Chandrasekhar limit?

Answer 34

1.44 solar masses

Question 35

Where are white dwarfs in HR diagram?

Answer 35

Bottom left

Question 36

Where are supergiants in HR diagram?

Answer 36

Along top

Question 37

Energy level

Answer 37

A discrete amount of energy that an electron within an atom is permitted to possess

Question 38

Ground state

Answer 38

The most negative value of energy level possible for an electron within an atom to possess-the most stable energy state of an electron

Question 39

Excited

Answer 39

An atom with one or more electrons that have absorbed energy and been boosted into a higher energy level

Question 40

Emission line spectrum

Answer 40

Set of specific frequencies of EM radiation (visible as bright lines in spectroscopy) emitted by excited atoms as their electrons move between energy states (losing the corresponding amount of energy in the form of photons as they do so) Every element has a characteristic line spectrum

Question 41

Absorption line spectrum

Answer 41

A set of specific frequencies for EM radiation (visible as dark lines in an otherwise continuous spectrum spectroscopy). They are absorbed by atoms as their electrons are excited between energy states by absorbing the corresponding amount of energy in the form of photons. Every element has a characteristic line spectrum

Question 42

Spectral line

Answer 42

A line in an emission or absorption line spectrum at a specific wavelength

Question 43

Photon

Answer 43

Quantum of electromagnetic energy

Question 44

Continuous spectrum

Answer 44

A spectrum in which all visible frequencies or wavelengths are present

Question 45

What are gas discharge tubes used for?

Answer 45

Observing spectra of a particular element

Question 46

How does a gas discharge tube work?

Answer 46

- particular gas is trapped in the tube and a high voltage is applied across the tube - electrons are emitted from the cathode and accelerate to wards the anode gaining KE - electrons collide with gas atoms atoms causing them to get excited and gain energy - gas atoms de-excited by emitting photons to lose the energy, causing the tube to light up