astrophysics Flashcards
What are the classifications of stars based on their color?
Stars can be classified into:
* Yellow stars
* Red dwarfs
* Blue giants
* Red supergiants
These classifications are based on the star’s color and surface temperature.
How does a star’s color relate to its temperature?
A star’s color is related to its surface temperature:
* Red stars are the coolest (around 3000 K)
* Blue stars are the hottest (around 30,000 K)
The color of a star indicates its temperature, with bluer stars being hotter.
What happens to a star’s color as it expands and contracts?
As a star expands, it cools and becomes redder; as it contracts, it heats up and becomes whiter.
This change is due to the relationship between temperature and color.
What are the initial stages of star formation?
The initial stages of star formation are:
* Nebula
* Protostar
* Main sequence star
All stars follow these stages as they begin to form.
What is a nebula in the context of star formation?
A nebula is a giant interstellar cloud of gas and dust from which stars form.
Nebulae are the starting point for the formation of stars.
What defines a protostar?
A protostar is a hot ball of gas that forms when gravity pulls particles closer together in a nebula.
The density and temperature of the protostar increase due to particle collisions.
What characterizes a main sequence star?
A main sequence star is defined by the initiation of nuclear fusion reactions in its core, achieving stability.
During this phase, the star is in equilibrium.
What are the evolutionary stages of a solar mass star after the main sequence?
The stages are:
* Red giant
* Planetary nebula
* White dwarf
This sequence describes the final life stages of a low-mass star like the Sun.
What occurs when a solar mass star becomes a red giant?
The star expands and cools as it begins to fuse helium after hydrogen fusion decreases.
This leads to the star’s outer layers expanding significantly.
What happens to a star after it becomes a white dwarf?
The white dwarf cools down over time, and the energy it emits decreases.
This marks the end of the star’s active life cycle.
What are the stages of a high-mass star after the main sequence?
The stages are:
* Red supergiant
* Supernova
* Neutron star (or black hole)
These stages differ significantly from those of lower mass stars.
What characterizes a red supergiant?
A red supergiant forms when a high-mass star begins to fuse helium and expands as hydrogen fusion decreases.
This stage is similar to the red giant phase but occurs in more massive stars.
What is a supernova?
A supernova is a gigantic explosion that occurs when the fusion reactions in a red supergiant cannot continue, causing core collapse.
This event ejects the star’s outer remnants into space.
What forms at the center of a supernova explosion?
A neutron star forms at the center of a supernova explosion.
If the star is massive enough, it may continue collapsing to form a black hole.
What is a black hole?
A black hole is an extremely dense point in space from which not even light can escape.
Black holes are formed from the remnants of massive stars after a supernova.
Fill in the blank: The life cycle of a solar mass star ends with a _______.
white dwarf
This marks the final stage of a low-mass star’s life cycle.
True or False: A lower mass star fuses helium into heavier elements like iron.
False
A lower mass star fuses helium into light elements, whereas a higher mass star can fuse it into heavier elements.
What is the definition of the Universe?
A large collection of billions of galaxies and the entirety of space.
The Universe encompasses all known matter, energy, planets, stars, galaxies, and the contents of intergalactic space.
What is a galaxy?
A large collection of billions of stars.
Examples include the Milky Way, Andromeda, and various other galaxies.
What is the position of the Sun in our Solar System?
At the centre of our Solar System.
The Sun is a star that provides light and heat to the planets orbiting it.
How many planets are in our Solar System?
Eight planets.
The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
What affects an object’s weight on different planets?
Gravitational field strength.
Weight is the force acting on an object due to gravitational attraction.
What is the approximate gravitational field strength (g) on Earth?
10 N/kg.
This value indicates the force of gravity acting on a 1 kg mass.
What is the relationship between mass and weight on different planets?
Mass remains constant, but weight changes depending on gravitational field strength.
An object’s weight will vary significantly on different planets, especially gas giants.
