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Flashcards in Space Physics Deck (72)
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1

What type of star is our star classed as?

-Main sequence star
- dwarf star

2

What is the mass of out sun?

1 Solar Mass (2 x 10^30)

3

What is the typical mass of a star?

One greater than that of 1 Solar Mass (1M)

4

Where does fusion occur in the star?

the core only

5

What is the only type of fusion in a star?

Hydrogen to helium

6

What are located on the sun, in parts where it is cooler?

Sun spots

7

What are the layers of the sun (outer to innermost)?

Corona, chromosphere, photosphere with convection zone and core

8

What can be seen coming off the outside of the chromosphere?

Prominence

9

What is the temperature of the core of a main sequence star?

15 million Kelvin

10

What is the temperature of the photosphere of a main sequence star?

5,700 Kelvin

11

What is the visible part of a main sequence star?

Photosphere

12

What is found in the radiative zone?

Metal ions

13

What is found in the convection zone?

Atoms of helium and hydrogen

14

What is dust?

Any atoms or molecules that are not helium or hydrogen

15

Describe the formation of a main sequence star:

-Large mass of gas and dust begin to collapse gravitationally due to non-uniform density
-Transfer of g.p.e to k.e. results in an increase of temperature at the centre of the cloud
-When temperature is high enough, thermonuclear fusion initiates; hydrogen nuclei fuse together to form Helium nuclei
-After some time, an equilibrium is established between the continued gravitational collapse and the radiation pressure of photons emitted by the core
- A main sequence star is formed

16

Describe how a red giant is formed from a main sequence solar mass star:

- Hydrogen in core is exhausted
- Fusion ceases
- Radiation pressure is lost
- So equilibrium between gravitational collapse and radiation pressure is lost
-The core collapses
- G.P.E is converted into kinetic energy so temperature of the core increases
- Temperature is then sufficient for Helium fusion to initiate
- Increased temperature of core creates greater radiation pressure- star expands
- A red giant is formed

17

Describe the key features of a Red Giant:

-cooler surface than a main sequence star
-more luminous due to increased surface area

18

What is the composition of a white dwarf core?

Diamond

19

Describe how a red giant evolves further to a white dwarf:

-Helium in the core is exhausted
- Fusion ceases
- Radiation pressure is lost
- Equilibrium between gravitational collapse and radiation pressure is lost
- Core collapses
-G.P.E is converted into K.E. so the temperature of the core increases
- However, temperature is insufficient for carbon fusion to initiate
- Core continues to collapse until new equilibrium is established between gravitational collpase and electron pressure
-Outer layers of the star are 'left behind' to form a planetary nebula
-remaining mass is known as a white dwarf

20

Describe the key features of a white dwarf:

- denisty a million times greater than a main sequence star
-radius 100 times smaller than main sequence star (7000km)
- surface temperature around 100,000K compared to 1000K for main sequence star
- very low luminosity due to very small surface area

21

Describe the process at the end of the life of a star with a mass greater than 8 solar masses:

- After a long sequence of fusion events, the core of the star ends up as iron
- Iron fusion is endothermic
-The energy for iron fusion comes from the layers of the star outside the core
- All the star's energy pours into the core in a fraction of a second
- A supernova explosion occurs

22

What could the result objects be of a supernova?

- Neutron Star
- Black Hole

23

What is the mass of a Neutron star supernova remnant?

1.5 solar masses

24

What is the mass of a black hole supernova remnant?

2.5 solar masses

25

What prevents further collapse in a neutron star?

The strong nuclear force

26

What is a neutron star made of? Why?

Made of neutrons - all the protons absorb electrons during the supernova and turn into neutrons

27

What is the density of a neutron star like?

Millions of times greater than normal matter

28

What is formed with a black hole?

A point of infinite density (singularity)

29

What orbits a black hole? Why?

An accretion disc orbits the black hole, created by the gravitational pull

30

What are the key properties of a neutron star?

- Rotates very rapidly
- Has very strong magnetic fields
- Produces very strong beams of radiowaves
- Radiowaves beam out across space