Astronomy Study Guide
Black Holes
A black hole is formed after a supernova when the core is very large. It collapses and forms a small hole with such strong gravity that not even light escapes from it.
What are meteorites? How do they help us to learn about the early solar system?
Meteorites are rocks in space from the beginning of our universe. They contain elements that tell us what was happening when our universe was formed. They are also called asteroids.
A star forms from a BLANK
Nebula
What evidence is known that supports the idea that a supernova gave birth to our solar system?
Nickel 60 was found in meteorites that have hit Earth. Nickel 60 is the decay product of Iron 60, which is produced by supernovas. This means that it is plausible that a supernova gave birth to our solar system.
What evidence do scientists use to tell which elements are released when a supernova explodes?
Scientist look at dips in the graphs of supernova explosions to identify the elements being released.
What kind of stars have no habitable zone?
Small stars, planets cannot spin while rotating around small stars making one side too hot and one too cold. Clusters of stars, a planet would have to be in the habitable zone for several stars at once.
In general BLANK stars have a longer lifespan because they burn fuel at a slower rate
Smaller
Protostars and Nebula
Space is full of thinly spread gas and dust called interstellar medium. When interstellar medium clumps together inside it forms protostars, stars that cannot yet fuse hydrogen. The protostars for when gravity pulls them together; this process is call accretion. When the protostar reaches 10 million degrees kelvin it can begin fusion. These new stars then enter the main sequence in the Hertzsprung-Russel diagram.
Equilibrium
Stars in the main sequence are in a state of equilibrium. Gravity pushes them inwards and the radiation from fusion pushes them outward. They remain like this until the star stops fusion.
A high mass star experiences a BLANK explosion and then becomes a BLANK or a BLANK
Supernova, neutron star, black hole
Habitable zone
The area around a star where it is not too hot or cold for life to exist
Why didn't Wilson and Penzias expect to find microwaves from space in 1964?
The big bang was not a prevalent theory at the time. So, when their machine was pointed towards empty space, all they should have found was empty space.
Why did scientists decided to simulate two neutron stars colliding?
They wanted to prove that colliding two neutron stars could form a black hole.
For what did Wilson and Penzias win the nobel prize?
They won the nobel prize for discovering the remnants of radio waves left over from the big bang. This was a brand new discovery.
What happens to time in strong gravitational fields?
Time slows down as gravity increase, inside a black hole time move much slower.
Helium
Two protons and two neutrons and two electrons
Size of the unvierse
We can't know it because it is always changing
The first stars formed after BLANK years
1 billion years
Evidence for Big Bang
1. Expansion 2. Cosmic background radiation 3. Abundance of light elements
The Sun formed after BLANK years
9 billion years
Low Mass Stars.
A lower mass means a slower rate of combustion. This also means a longer main sequence, which explains its longer lifespan. The smallest stars are called Red dwarfs. Some Red dwarfs have been around since the Big Bang, because their lifespan is longer than our universe has been alive.
Why is a snowplow a good model for how a supernova shock could affect a nebula
A snowplow is a good model because it could either push the snow and cause it to compress and form balls, or it could run over the snow and smush it.
Massive Stars
A supergiant is a star that is ten times larger than the Sun, it has the shortest lifespan. Supergiant fuse hydrogen and helium creating carbon. As the star begins to collapse it fuses carbon and move to heavier and heavier elements. When the star reaches iron it collapses.
Supernova
A supernova is when a supergiant cannot maintain equilibrium. The core is so large that when it explodes it creates enough heat to form heavy elements such as tin, gold, and lead. After the supernova the dust and gas reforms into a nebula so new stars can form.
White Dwarf
A white dwarf is the exposed core of a Red Giant that is left behind after a planetary nebula is formed. The pressure form electrons keeps them from collapsing. They are roughly the size of the Earth, they have lifespans that are longer than the universe.
Stars and Elements
All elements come from stars. They are built from hydrogen which is combusted inside the stars through nuclear fission. Heavier elements such as iron require very large stars. When the stars explode the elements are scattered which is how they get to Earth
What is the difference between an absorption and emission spectrum?
An absorption system shows the wavelengths that an object reflects back. An emission spectrum shows the wavelengths an object produces.
Mass and Lifespan
As mass increases lifespan decrease. This is because the larger stars will burn through fuel faster than the smaller stars.
A BLANK is a region of space with very high gravity that has a singularity at its center.
Black hole
How do scientists confirm the presence of black holes?
Black holes draw matter from other stars and they bend the light around them.
Stars that do not have sufficient mass to have fusion in the core become BLANK
Brown dwarfs
Brown Dwarfs
Brown dwarfs are stars that never got hot enough to fuse hydrogen. They are larger than Jupiter but smaller than the Sun. They give off light even though they are not real stars.
In the beginning of old age, the star's core BLANKS in an effort to keep fusion occurring.
Collapses
CMB
Cosmic background radiation - a 2.7k glow detected with radio telescopes found throughout the universe. It is considered a remnant of the initial heat found early in the universe at the time of the singularity.
Once fusion stops, BLANK can no longer be maintained
Equilibrium
More massive stars are able to maintain equilibrium a bit longer than smaller stars because they BLANK
Fuse carbon into heavier elements
Fusion
Fusion is when under intense heat and pressure hydrogen is turned into helium. This is caused by the proton-proton chain reaction.
Hubble Law
Galaxies are moving away from us at speed proportional to their distance from us. V = HD, H is a constant and is always changing
How do gamma ray bursts give us clues about the magnitude of gravitational and magnetic forces?
Gamma ray bursts show us that magnetic fields can be in layers that expand to form the bursts.
Equilibrium is the balance between BLANK and BLANK
Gravity, Fusion
Equation for Fusion
H + H = He + n + energy
H-R Diagram
H-R means Hertzsprung-Russell diagram. It shows absolute magnitude and temperature. Hottest stars are plotted on the left side and get colder as you move right. This chart lets scientists find patterns among groups of stars.
After the hydrogen is used up the only way for the star to maintain equilibrium is to fuse BLANK to BLANK
Helium, Carbon
Once fusion of BLANK and BLANK has begun, stars are on the BLANK
Hydrogen, Helium, Main Sequence
Age of the universe
Inverse of Hubble's constant
Our sun will never become a black hole because it does not have enough BLANK
Mass
If atmospheric gas like methane can absorb certain wavelengths of light, why do you think it is better to inspect Mar's atmosphere from a satellite in orbit than from an observatory on Earth?
It is better to observe from a satellite because the wavelengths will be less likely to pass through more gas altering them further.
Are Black Holes Rare?
No, they are the center of every galaxie
Hydrogen
One proton and one neutron
Medium Stars
Our Sun is a medium star. When it runs out hydrogen the heat from its collapse will bring it back to a protostar stage. However, it is now called a Red Giant and is several hundred times larger than before, which makes it appear brighter. This phase last a few million years until the outer shell is blown away and the star turns into a planetary nebula.
A middle mass star then forms a BLANK and then become a BLANK, just like a low mass star
Planetary nebula, white dwarf
A star that has not yet begun nuclear fusion is called a BLANK
Protostar
Quark
Quarks are the building blocks of matter, and are smaller than protons and neutrons
Middle and high mass stars become BLANK or BLANK after the main sequence. Our sun might become on in about 5 billion years.
Red giants or supergiants
How do elements in the atmosphere help scientists to identify types of supernovas?
The elements released allow the scientists to identify the supernova because heavier elements needed a larger supernova to have formed.
What happens when light travels through a prism or diffraction grating?
The light gets separated into the colors of the rainbow.
Main Sequence
The main sequence is where stars spend most of their lifetime. It is when they are fusing hydrogen at their core. The Sun is in the main sequence.
What are the most abundant stars
The most abundant stars are red dwarfs because none of them have died because their lifetime is longer than the age of the universe
Planetary Nebula
The planetary nebula is the outer layer of stars that have died. This layer contains valuable elements.
Singularity
The point in a universe at which the density is infinite, heat is infinite, and there is minimal volume
What was Einstein's revolutionary idea?
The theory of general relativity, it said that mass and energy warp the space around them.
Old Stars
When a star become old it runs out of hydrogen and the outward force decrease. Because of this the star slowly collapses.
Neutron Star
When a supernova explodes a core usually remains. In this core protons attach to electron and the charges cancel out and creates neutrons. These cores are called neutron stars. They can resist gravity by repulsing nucleus. This means that they are small, as small as 24 kilometers across. However, they are extremely dense and can weigh up to twice the Sun. A pulsar is the name of a Neutron star that is shooting electromagnetic radiation at the Earth.
Low mass stars become BLANK after the main sequence. These are small, dim, stars with high density.
White dwarfs
How do we use evidence from received light to identify the composition of stars?
You can compare the light reflected back to know elements to identify which ones match know elements.
Order from hottest to coolest: yellow, white, red, blue, orange
blue, white, yellow, orange, red
