Space Physics Flashcards
(16 cards)
1
Q
The life cycle for smaller stars?
A
- cloud of dust and gas
- protostar
- main sequence star
- red giant
- white dwarf
- black dwarf
2
Q
The life cycle for larger stars?
A
- cloud of dust and gas
- protostar
- main sequence star
- red super giant
- supernova
- neutron star or black hole
3
Q
How does a protostar form?
A
- force of gravity pulls dust and gas together to form protostar
- temperature rises as star gets denser and more particles collide with each other
- when temperature gets high enough - hydrogen nuclei undergo nuclear fusion to form helium nuclei
- gives out large amounts of energy - keeps core of star hot
4
Q
How does a main sequence star form?
A
- star enters stable period where outward pressure caused by nuclear fusion trying to expand star balances force of gravity pulling everything inwards
- called a main sequence star
5
Q
How does a small sized star become a white dwarf, and then a black dwarf?
A
- becomes unstable and ejects outer layer of dust and gas - leaves behind a hot, dense solid core - a white dwarf
- as white dwarf cools down - it emits less and less energy - when it no longer emits a significant amount - it is called a black dwarf
6
Q
How do red giants and red super giants form?
A
- eventually hydrogen begins to run out - star swells into a red giant/red super giant
- becomes red because surface cools
- fusion of helium occurs - heavier elements created in core of the star
7
Q
How does a supernova form?
A
- big stars start to glow brightly again as they undergo more fusion and expand and contract several times, forming elements as heavy as iron in various nuclear reactions
- eventually they explode in a supernova - forming elements heavier than iron and ejecting them into the universe to form new planets and stars
- stars and their life cycles produce and distribute all naturally occurring elements
8
Q
How do neutron stars and black holes form?
A
- exploding supernova throws outer layers of dust and gas into space - leaving a very dense core called a neutron star
- if star becomes massive enough - it will become a black hole - a super dense point in space that not even light can escape from
9
Q
What does the size of the orbit depend on?
A
- closer you get to star/planet - stronger gravitational force is
- stronger the force - faster the orbiting object needs to travel to remain in orbit
- for object in stable orbit - if speed of object changes - radius of orbit must too
10
Q
Why do planets orbit the sun?
A
- planet has instantaneous velocity driving it forward
- sun pulls on planets with gravitational force - acts as centripetal force that keeps planets in orbit
- this force is the resultant force on the planet
- forward motion of planet balances the inward pull - they move in a stable orbit
11
Q
What is red shift?
A
- when we look at light from most distant galaxies - find that the wavelength has increased
- wavelengths are all longer than they should be - shifted toward red end of spectrum
- called red shift
12
Q
What does red shift prove?
A
- suggests source of light is moving away from us - measurements of red shift indicate that distant galaxies are moving away from us very quickly
- more distant galaxies have greater redshifts
- further away galaxy is - faster it’s moving away - greater its redshift
13
Q
What is the big bang theory?
A
- intitially - all matter in universe occupied very small space - tiny space was very dense - so very hot
- it exploded - space started expanding - expansion still going in
14
Q
Evidence for big bang theory?
A
- in 1965 scientists first detected microwaves coming from every direction in space
- existence of cosmic microwave background radiation can be explained only by big bang theory
15
Q
What is dark matter?
A
- an unknown, invisible substance in universe that does not emit light or any form of electromagnetic radiation
16
Q
What do scientists think dark energy and dark matter are responsible for?
A
- believe dark matter holds galaxies together by providing extra gravity
- believe dark energy is responsible for the accelerated expansion of the universe
