Astronomy 300 Final
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144 Terms
What is the sun’s age?
4.6 billion years old
What is the sun’s orbital period around the Milky Way galaxy?
220 million years approximately
What is the sun’s orbital speed around the Milky Way galaxy?
About 220 kilometers per second
What is Thermonuclear Fusion?
The process of combining lighter elements into heavier ones
What causes Thermonuclear Fusion?
Pressure of the sun and high temperatures in its core fusing hydrogen atoms together.
What is the breakdown of E=mc2
E=energy emitted m=the mass that’s lost c=the speed of light squared.
What is the sun’s luminosity?
The total amount of energy emitted by the sun per second, measured in watts.
How much mass is used during nuclear fusion?
4 hydrogen atoms are used per reaction
What is the location of Nuclear Fusion on the sun?
Nuclear fusion occurs in the core of the sun.
Which layer of the sun contains the energy/heat generated by the Nuclear Fusion?
The radiative zone, where energy is transported outward by radiation.
Describe the Convection Layer of the sun:
The outer layer of the sun where energy is transported by convection currents, allowing hot plasma to rise and cooler plasma to sink.
What is the Photosphere of the sun?
The visible surface of the sun.
What is the Chromosphere of the sun?
The plasma layer that is heavily manipulated by magnetic fields. The Chromosphere has solar flares.
The sun’s magnetic field is so big that it surrounds the entire solar system, known as the_____
Heliosphere.
What are Sunspots?
Dark spots on the sun's surface caused by magnetic activity, cooler than surrounding areas.
Stars are born from large dense clumps of gas known as ________
Stellar Nurseries (or Molecular Clouds).
What are the different features of a star?
Color, size, fusion, age
What colors can stars be?
Stars can be blue, white, yellow, orange, or red, depending on their temperature.
T/F Stars that are younger are known as Main Sequence Stars:
True. Main Sequence Stars are in a stable phase of hydrogen fusion.
T/F The more mass the initial molecular cloud, the smaller the star.
False. The more mass the initial molecular cloud, the BIGGER the star.
The smallest stars are known as ________
Dwarf stars (or very low mass stars).
T/F Our sun is a low mass star:
True. It is sometimes called a yellow dwarf star, too.
Why don’t brown dwarf stars perform nuclear fusion?
They aren’t hot enough and their gravity isn’t high enough to create the pressure.
Why do brown dwarf stars appear brown?
They release infrared heat from the formation of the star.
T/F: Brown dwarfs die the same as the other dwarf stars.
False. Brown dwarf stars spend eternity cooling off, never officially dying.
T/F: Most stars are low mass stars.
True.
How are low mass stars different from brown dwarf stars?
Unlike brown dwarf stars, low mass stars are actually able to begin nuclear fusion.
The more mass a main sequence star has, the more ____ it consumes.
The more fuel it consumes.
How many years are red dwarfs thought to live?
Trillions
What color stars are considered “normal”?
Yellow/orange.
T/F: Our sun is a dwarf star.
True. Our sun is considered a yellow dwarf star.
How old is our sun?
4.6 billion years old.
About how many more years is our sun expected to live before it dies?
6 billion years left before expected to die.
High mass stars are big and appear what color?
White and blue.
What is another name for high mass stars?
High mass stars are also known as Giants, given that they can be extremely big compared to dwarf stars.
Red main sequence stars are _____in mass and don’t consume much fuel.
Smaller.
Yellow main sequence stars are _____in mass and consume more fuel.
Bigger.
Higher mass main sequence stars have _____temperatures and appear_____.
Have higher temperatures and appear more blue.
Low mass main sequence stars have _____temperatures and appear_____.
Have lower temperatures and appear more red.
What is the Hertzsprung-Russel Diagram?
This diagram is a graph that relates the luminosity, temperature, and mass of stars together.
What is a Globular Cluster?
A cluster of stars likely all born from the same molecular cloud.
What is Hydrostatic Equilibrium?
When gravity of the star is in balance without the outward pressure due to its hot internal gas.
A star must be in balance in order to maintain its_____.
Shape and size.
When do stars enter old age?
Stars enter old age when they stop fusing hydrogen.
T/F: When hydrogen fusion stops, the star becomes redder.
True: The star decreases and becomes more red.
What typically marks the death of a high mass star?
High mass stars may explode in a supernova at the end of their life cycle.
What happens when low mass stars enter old age?
When low mass stars get old, they stop fusing hydrogen and may become redder.
What are red giants?
Red giants are stars that have expanded and cooled after exhausting the hydrogen in their cores (resulting in a reddish appearance).
What are supergiants?
Supergiants are massive stars that have entered the later stages of their evolution.
What is a Planetary Nebula?
A planetary nebula is formed when a low mass star blows its atmosphere away from its core at the end of its life cycle.
What is a white dwarf?
A white dwarf is a small, dense star that remains after a low mass star has blown away its outer layers.
What is Electron-degenerate Pressure?
A pressure that supports a star against collapse, due to electrons occupying different energy states.
What is a Black Dwarf?
A black dwarf is a theoretical star that is what happens when white dwarfs give off all of their heat.
T/F: A star can only form by itself.
False. A star can form in pairs or even threes.
What is a Binary Star System?
A binary star system consists of two stars orbiting around a common center of mass.
What is a Binary White Dwarf System?
A pair of white dwarf stars that orbit each other, essentially two "dead" stars locked in a gravitational dance around a common center of mass
What is a Supernova Type 1A?
A type of supernova that occurs in binary systems where one star is a white dwarf, which accretes matter from its companion, leading to a thermonuclear explosion.
What is a Nova?
A nova is a strong increase in brightness of a star caused by a sudden fusion reaction on its surface, typically occurring in binary star systems where a white dwarf star accretes material from its companion.
What is the difference between a Supernova 1A and a Supernova Type II?
Type 1A supernovae result from the thermonuclear explosion of a white dwarf in a binary system, while Type II supernovae are caused by the core collapse of a massive star.
What are the 3 types of remnants left behind after a supernova?
Supernova remnant (left over gas from shockwave/explosion)
Blackhole
Neutron star
Def: An extremely dense, collapsed core of a massive star left behind after a supernova explosion, composed primarily of neutrons
Neutron Star
What type of star has the strongest magnetic field?
Neutron Star
What are neutron stars also known as?
Pulsars
Pulsars are known for emitting______
High amounts of radio waves and other forms of light.
Def: A region of space having a gravitational field so intense that no matter or radiation can escape.
Black Hole
What is “Spaghettification”?
If you entered a black hole, its gravity force would compress you from top to toe, while stretching you at the same time… thus, spaghetti.
What remnant is left behind after the death of a low mass star?
Supernova/Planetary nebula + white dwarf
What remnant is left behind after the death of a high mass star?
Supernova + black hole/neutron star
T/F: Eventually, all hydrogen will be used up in the universe.
True.
What is a galaxy?
A huge collection of gas, dust, and billions of stars and their solar systems.
What holds a galaxy together?
An galaxy is held together by gravity.
T/F: Many/All galaxies have a massive black hole at the center.
True.
How many galaxies are believed to be in the universe?
Upwards of 200 billion galaxies.
Edwin Hubble made new discoveries by studying what galaxy?
Andromeda Galaxy.
Who was the first to suggest Andromeda was a galaxy and not a nebula?
Edwin Hubble.
Elliptical galaxies have a _____ ellipsoidal or spherical appearance.
Smooth.
T/F: Elliptical galaxies have far less structure than spiral galaxies.
True.
What are galaxy clusters?
Galaxy clusters are large groups of galaxies that inhabit a specific location in the universe.
How are Elliptical galaxies formed?
It is believed that elliptical galaxies are formed from collisions and mergers of spiral galaxies.
T/F: Elliptical galaxies tend to be redder in color.
True. They have older stars that are in their red giant/supergiant phase.
What is another term for an elliptical galaxy?
“Red and dead galaxies”
What is a spiral galaxy?
A spiral galaxy is a galaxy with a rotating disc and spiral arms that curve out from a dense center.
T/F: Spiral galaxies are not able to form stars.
False. Spiral galaxies tend to have more gas and dust, making them prime for stellar formation.
How do spiral galaxies get their “arms?”
Likely from its galactic spin.
What is an irregular galaxy?
An irregular galaxy is a galaxy that doesn't have a distinct shape, like a spiral or elliptical galaxy.
What are the subtypes of irregular galaxies?
Dwarf galaxies, type 1 irregular, type 2 irregular
What is a dwarf galaxy?
A galaxy that is very small and has no structure like spirals or ellipticals.
What is a type 1 irregular galaxy?
A type 1 irregular galaxy has some structure but not enough to be classified as either main galaxy.
What is a type 2 irregular galaxy?
A galaxy with no structure at all.
What is a Virgo super cluster?
A large collection of other clusters. This cluster houses our “local group” or our neighborhood of galaxies within the cluster.
What are the 3 large galaxies that make up our “local group?”
Milky Way, Andromeda, Triangulum
T/F: The Milky Way will eventually combine with Andromeda galaxy.
True.
What is Dark Matter?
dark matter is a hypothetical form of matter that does not interact with light or other electromagnetic radiation.
What are the two explanations for the galaxy traveling much faster than expected?
Dark matter
MOND
What does MOND stand for?
Modification of Newtonian Dynamics
What percent of the universe is comprised of “normal” matter?
5%
What percent of the universe is comprised of Dark Matter?
27%
What is the remaining 68% of the universe comprised of?
Something else-or Dark Energy.
T/F: Dark matter can have mass, gravity, and can bend light.
True.
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Flashcards (169)