# The Physics of Astrophysics (Option E) Part 2

30 Questions covering 10.5 to 10.7 of HL Option (E) Astrophysics. Requires knowledge of Stellar Parallax, Magnitudes and Stellar evolution of stars as well as some equations and numbers related to these topics.

The stellar parallax of a star is calculated from two observations made on the earth at least...?
Two times in one year
1 of 24
The parsec is defined as...? Units are shown, followed by the conversion factor from degrees.
1 / The angle in seconds (1') (1° / 60)
2 of 24
The equation defining the arc of a circle s, is s = rθ, where θ is the angle in radians, r is the radius. What is the equation defining the distance (D) to a star under observation where A.U is one astronomical unit.
D = A.U / θ
3 of 24
What is the magnitude of distance satellite telescopes can measure in parsecs?
1000pc
4 of 24
Cepheid variables are stars...?
Which are unstable and undergoe periodic expansions and contractions, leading to similar variations in apparent brightness
5 of 24
For Cepheid variable stars, the period of their variations in brightness and their luminosity are...?
Linearly related
6 of 24
The equation relating the apparent magnitude (m) of a star and it's absolute magnitude (M) is...?
M= m - 5log (d / 10)
7 of 24
If Polaris has an apparent magnitude of 1.99 and Betelgeuse 0.41, how much brighter is Betelgeuse than Polaris?
4.29
8 of 24
The formation of a proto-star involves...?
The contraction of a large cloud of gas due to the gravitational attraction of the gas molecules, causing a hot more dense ball to form which gives out light.
9 of 24
The formation of a pre-main sequence star from a proto-star involves...?
An increase in the stars mass until the radiation is great enough to blow away the dust cloud and stabilize its mass
10 of 24
The formation of a main sequence star from a pre-main sequence star involves...?
The fusion of hydrogen which causes an increase in temperature and outward pressure which balances the inward force of gravity
11 of 24
The formation of a red giant star from a main sequence star involves...?
The formation of a core of helium from hydrogen fusion, causing a compression of the star due to less thermal pressure. This then causes further fusion of helium which causes the star to expand exponentially.
12 of 24
The largest nuclei in a star which can theoretically undergo fusion to produce energy during the main sequence is...?
Silicon
13 of 24
Small stars do not have the necessary temperatures or pressures to fuse...?
Carbon nuclei
14 of 24
The Pauli exclusion principle prevents small cooling stars from contracting past the core of carbon. The Pauli exclusion principle states that...?
No two Fermions (particles with half spin) can occupy the same quantum state
15 of 24
The Pauli exclusion principle means that there is an 'electron degeneracy pressure'. The electron degeneracy pressure means that...?
There is a resulting emergent repulsive force, manifested as a pressure against compression of matter into smaller volumes of space
16 of 24
The mass of white dwarfs cannot be greater than the 'Chandrasekhar limit' or it will overcome the electron degeneracy pressure. The value of the 'Chandraskhar limit' is...?
< 1.4 solar masses
17 of 24
White Dwarfs therefore cannot be formed from main sequence stars which are bigger than...? (Or else their cores will be too massive)
> 4 solar masses
18 of 24
A star with a mass greater than 4 solar masses fuses elements in layers up to Iron, once a certain mass of iron is gathered in the core...?
Protons in the star will combine with electrons forming neutrons and reducing the volume of the core of the star
19 of 24
After a type 2 supernova, all that remains of the star is...?
A neutron star
20 of 24
A neutron star will not collapse further unless it's mass exceeds the Oppenheimer-Volkoff limit of...?
> 3 solar masses
21 of 24
Neutron stars can form pulsars which are...?
Stars which emit x-ray radiation from their poles due to the acceleration of charged particles in their rotating magnetic field
22 of 24
Pulsars rotate at extremely fast because of the conservation of...?
Angular momentum
23 of 24
In order for a Neutron star to form a black hole, it's mass must be great enough to overcome the 'neutron degeneracy pressure'. It's mass must therefore be greater than...?
> 3 solar masses
24 of 24

## Other cards in this set

### Card 2

#### Front

The parsec is defined as...? Units are shown, followed by the conversion factor from degrees.

#### Back

1 / The angle in seconds (1') (1° / 60)

### Card 3

#### Front

The equation defining the arc of a circle s, is s = rθ, where θ is the angle in radians, r is the radius. What is the equation defining the distance (D) to a star under observation where A.U is one astronomical unit.

### Card 4

#### Front

What is the magnitude of distance satellite telescopes can measure in parsecs?

### Card 5

#### Front

Cepheid variables are stars...?