Astrophysics

Question 1

Life Cycle of a Star

Answer 1

Protostar, Main Sequence, Red Giant, white dwarf, Black Dwarf

or if star has 1000 times the radius of our Sun:

Protostar, Main Sequence, Red Supergiant, Supernova, Neutron Star/Black hole

Question 2

Comet; orbit, most gpe and ke, Tail

Answer 2

Elliptical orbit, most gpe furthest away from Star, most ke closest to sun, tail faces away from sun at all times

Question 3

Main sequence star; what is it?

Answer 3

A star that releases energy from fusion of hydrogen to form helium.

Question 4

Protostar formation

Answer 4

Gravity begins to pull the gases together into a ball

Question 5

Red giant

Answer 5

fuses helium into heavier elements

Question 6

White dwarf

Answer 6

Fusion stops, end of life, collapses, 50,000K or more

Question 7

Black dwarf

Answer 7

white dwarf cools down, dark cold star.

Question 8

Red supergiant

Answer 8

1000 radius of sun, heavier elements fused- eg iron. Millions of years later runs out of fuel, cools down, collapse. heat inside supernova

Question 9

Supernova

Answer 9

Supergiant collapses, nuclear reaction, star explodes, new stars can form.

Question 10

Neutron Star

Answer 10

RSG: Gravitational forces; centre collapses; condensed matter; neutron star - only neutrons

Question 11

Black Hole

Answer 11

RSG: collapses; star disappears into a microscopic point - black hole

Question 12

Apparent Magnitude

Answer 12

How bright a star is from earth.

Question 13

Absolute Magnitude

Answer 13

How bright a star is from 10 parsecs away

Question 14

Evolution of universe theory

Answer 14

The Big Bang theory

Question 15

Big Bang Theory (probs don’t have to know - don’t memorise just brief idea)

Answer 15

0.1 second; 10^12K. No protons or neutrons. Highly energetic particles and photons.

Few seconds; Cooled- neutrons, protons and electrons exist

3 minutes; 10^9K

30 minutes; 10^8K nuclear fusion - deuterium and helium

700000 years; 4000K ; nuclei attract electrons - orbit, hydrogen and helium gas

Next billion years; gravity forms stars and galaxies

Now; expanding and evolving

Question 16

Evidence for Big Bang

Answer 16

CMB, Red shift

Question 17

Cosmic Microwave background radiation

Answer 17

remains of energy created by the Big Bang, The short wavelengths of the gamma radiation emitted in the initial explosion are believed to have become stretched due to the expansion of space into longer wavelength microwaves.

Question 18

Red shift

Answer 18

everything is expanding- getting redder. means it all must have been in the same place at one time

Edwin Hubble looked at the light of galaxies further away from Earth and realised that the dark absorption lines showed greater red shifts. He concluded that distant galaxies had bigger red shifts because they were moving away faster.

Question 19

Velocity of a galaxy formula

Answer 19

change in wavelength / reference wavelength

=

velocity of galaxy / speed of light

Question 20

orbital speed equation

Answer 20

orbital speed = (2 x pi x orbital radius) / time period