# The Physics of Astrophysics (Option E) Part 1

29 questions on Topics 10.1 to 10.4 of HL Astrophysics. Requires knowledge of magnitudes of the universe, the stellar types and star types as well as equations and definitions of related subtopics.

?
The observed movement of the stars at night is due to...?
The rotation of the earth on its axis
1 of 23
The observed retrograde motion of planets is caused by...? (Need help? search 'retrograde motion')
The relative orbits of the earth and the observed planet
2 of 23
Precession caused by the gravitational pull of the sun on the earth (being a non-perfect sphere) is observed on the earth as...?
The rotation of the axis on which the earth spins
3 of 23
Galaxies are separated by distances in the magnitude of...?
10 E6 light years
4 of 23
The main stage fusion process involves mainly...?
The fusion of hydrogen to create helium through the proton-proton chain
5 of 23
The proton-proton chain can be represented by the equation...? (where (e+) is a positron (ve) is an electron neutrino and (ɣ) is gamma radiation)
4H = He + 2ve + 2ɣ + 2e+
6 of 23
Stable stars...?
Do not get bigger or smaller because the gravitational force is balanced by the radiation pressure due to fusion
7 of 23
The luminosity of a star is measured in...?
Joules per Second (J/s) (Watts)
8 of 23
The luminosity of a star depends only on...?
Its temperature and size, L = σA(T^4)
9 of 23
The apparent brightness (b) of a star is measured in...?
Watts per Square Meter (W/m^2)
10 of 23
The Wien displacement law states that the peak intensity wavelength (λmax) is related to the temperature of the star (T) by the equation...? (where k is a constant with units meters))
λmax = k / T
11 of 23
Stars emit black body radiation because...?
Of the energy of the electrons which allows them to transition between orbitals in atoms
12 of 23
The black lines in the emission spectra of a star represent...?
The patterns of absorption of the elements present in the star
13 of 23
What is the order of the (illogical) Harvard star classes in order of decreasing temperature?
O, B, A, F, G, K, M
14 of 23
The Doppler Shift observed in the light from distant stars is when...?
The light from stars which are moving away relative to the earth have longer wavelength absorption patterns
15 of 23
A Hertzsprung-Russell diagram plots...?
Spectral class or temperature on the x axis with luminosity on the y axis
16 of 23
Giant stars are stars which...?
Have a high luminosity and relatively low temperature
17 of 23
Supergiant stars are stars which...?
Have an extremely high luminosity and relatively low temperature
18 of 23
White Dwarfs are stars which...?
Have a relatively low luminosity and an extremely high temperature
19 of 23
Variable stars are stars which...?
Experience variations in their luminosity
20 of 23
The luminosity of a star is generally related to it's mass by the equation...?
L ∝ m^3.5
21 of 23
A binary star system can be identified by...?
Two periodic drops in apparent brightness of different magnitudes
22 of 23
Spectroscopic binary is when...?
A star is identified by its periodic variation between red and blue shift
23 of 23

## Other cards in this set

### Card 2

#### Front

The observed retrograde motion of planets is caused by...? (Need help? search 'retrograde motion')

#### Back

The relative orbits of the earth and the observed planet

### Card 3

#### Front

Precession caused by the gravitational pull of the sun on the earth (being a non-perfect sphere) is observed on the earth as...?

### Card 4

#### Front

Galaxies are separated by distances in the magnitude of...?

### Card 5

#### Front

The main stage fusion process involves mainly...?