Astronomy Flashcards
Black hole
The final stage of death for the largest stars. It turns into a neutron star but then keeps collapsing. It is a point so dense it infinitely bends gravity.
Chromosphere
A layer between the photosphere and corona.
Convective zone
The place between the radiative zone and the photosphere. This is where heat and light travels out of the sun via convection, and it takes about a month to pass through. Plasma warms up and rises to the surface of the sun where it cools off and sinks back to the bottom where it warms up again. The process then repeats itself.
Core
The center of the sun that is about 15.7 million kelvin. This is where nuclear fusion happens which creates the heat and light we see.
Corona
Thin, wispy lines that spread away from the sun. About 1-2 million kelvin.
What does CME stand for?
Coronal mass ejection
What is a CME?
A chunk of plasma that flies off of the sun when magnetic field lines cross. This can cause surges in electricity if it hits the earth, possibly causing transformers to explode.
What is an H-R diagram?
A diagram that measures the magnitude (y-axis) and temperature (x-axis) of a star, therefore determining where a star is in its life cycle.
What is a main sequence star?
A star that is in the middle of its life. Most stars are main sequence stars. It is in the stage where it fuses hydrogen atoms.
Emission spectrum
The spectrum of light something emits that tell you what elements it is made of. It can be viewed with a spectroscope.
Nebula
A collection of dust and gas in space where stars are born.
Neutron star
After a high mass star collapses and has a supernova, the core collapses into a neutron star.
Nuclear fusion
Where Hydrogen 2 atoms fuse together in the core to make one Helium atom. This produces heat and light. Temperature must be over 10 million kelvin for nuclear fusion.
Photosphere
The visible surface of the sun. About 6000 kelvin. It is between the convective zone and chromosphere.
Planetary nebula
A collection of gas that is released from a dead star when a low-mass star turns into a white dwarf.
Plasma
The state of matter that stars are. A gas that is so hot the electron is stripped from the nucleus. Very conductive.
Prominence
A magnetic field line that is poking very far out of the photosphere and carries some plasma with it. Causes no harm to earth.
Radiative zone
Where heat and light travel via radiation. Between the core and convective zone. Particles are so tightly packed that it takes heat and light 100,000 to 200,000 years to pass through.
Red giant
A star that is near death. The star expands when other elements other than hydrogen start to fuse because the pressure pushing out is just slightly stronger than gravity.
Solar activity cycle
The cycle that occurs as magnetic field lines start to cross. A full cycle lasts 22 years.
Solar flares
An explosion that throws particles off of the sun. The particles travel faster than a CME but aren’t as damaging to electrical grids than CMEs.
Solar wind
A stream of particles constantly coming off the sun. Not dangerous.
Sunspots
Where magnetic field lines poke out of the photosphere which causes the plasma in the convective zone to cool off which gives it a darker appearance.
Supergiants
When a high mass star is near death. The star expands when other elements other than hydrogen start to fuse because the pressure pushing out is just slightly stronger than gravity.
Supernova
When a high mass star stops fusing to iron, fusion completely stops which causes gravity win and the star to collapse. The outer layers bounce off of the iron core which causes an explosion.
White dwarf
The remnant of the death of a low mass star. It is the exposed core of the star after the outer layers puff away leaving the white dwarf to cool off in space. The star is about planet-sized.
What is a star made of?
Plasma
What is our sun made of?
91% Hydrogen
8.9% Helium
0.1% Metals
What are the layers of a star?
Core, radiative zone, convective zone, photosphere, chromosphere, corona
What happens in nuclear fusion?
Must be at least 10 million kelvin for fusion. It is where two atoms collide to make one atom. Heat and light are the remnant. This stage happens in the core.
Why doesn’t the force of fusion blow a star apart?
Because the pressure from gravity is equal to that of the fusion, therefore creating a perfect balance and keeping it intact.
What is the density of the sun?
1.41 grams per cm cubed
What causes the sun’s poles to flip?
The magnetic field lines getting too tangled. The poles flip every 11 years.
What happens to the sun’s magnetic field lines over time?
They get tangled. Since the sun is not a solid, the plasma at the equator moves faster than the plasma at the poles. This causes the magnetic field lines to tangle and stick out of the photosphere and cause solar storms.
In what direction do sunspots move towards the end of the solar cycle?
Towards the equator.
How are sunspots tied to the solar cycle?
More magnetic field lines stick out as they get more tangled towards the end of the cycle. Magnetic field lines sticking out is what causes sunspots.
How are solar storms tied to the solar cycle?
Magnetic field lines stick out more towards the end of a cycle and solar storms can only come from magnetic field lines poking out of the photosphere.
What are types of solar weather?
Solar wind, flare, CME, prominence.
What releases more energy: a flare or a CME?
A flare.
In OBAFGKM, which side is cooler and which is hotter?
O=Hotter
M=Cooler
What types of solar storms can wreak havoc on earth and why?
CMEs and Flares enter the earth’s atmosphere through the poles, causing lots of electromagnetic waves to flow through the air which could cause transformers to catch fire or explode, essentially wiping out the power grid.
What protects earth from solar storms?
Earth’s magnetic field.
What does a spectroscope do to the light that passes through it?
It breaks the light from a single material into its component colors.
What can you tell about an object by looking through a spectroscope?
You can tell what elements it is made of.
What can you tell about a star by looking through a spectroscope?
You can tell how far it is in its life cycle by what elements it is made of.
What is unique about each element on the periodic table?
They each have a unique spectrum.
What properties do all main sequence stars have in common?
All stars fuse 2 hydrogen atoms to make a helium atom.
What properties do all stars have in common?
They all fuse 2 atoms to make heat and light.
What are the temperatures and brightnesses for red giant stars?
Somewhat cool and dim
What are the temperatures and brightnesses for white dwarf stars?
Very hot and very dim
What are the temperatures and brightnesses for a supergiant?
very hot and bright
How do stars form?
A shockwave hits a nebula and a little of the gas and dust in the nebula breaks off. The chunk collapses and starts spinning. Gravity starts putting pressure and it keeps slowly shrinking until the core reaches 10 million kelvin and nuclear fusion starts.
What stage of life is a main sequence star in?
It’s adult stage. This is when it still is fusing hydrogen to make helium.
What happens that causes a star to start dying?
There is no more hydrogen in the core.
How does a high mass star die?
Fuses all the way to iron. Fusion stops and gravity causes the outer layers of the star to collapse in on the iron core. However, the core is so dense that the outer layers bounce back into a supernova and explode. The pressure from the other layers causes the core to collapse down to a neutron star. The really big stars keep collapsing down though, and they form a black hole.
How does a low mass star die?
After carbon is fused, the star is not hot enough to fuse further. When fusion stops, outer layers puff away and leave the core (white dwarf) to cool down in space.
What element does a high mass star stop fusing at?
Iron
What element does a low mass star stop fusing at?
Carbon
What is classified as a high mass star?
8x the mass of the sun or more.
What is classified as a low mass star?
Less than 8x the mass of the sun.
What is the Y axis on an HR diagram?
Magnitude
What is the X axis on an HR diagram?
Temperature
What types of stars are on an HR diagram?
Supergiants, giants, main sequence, white dwarfs
How does a star move throughout a HR diagram in its lifetime?
Low mass - Main sequence, giant, white dwarf
High mass - Main sequence, giant, supergiant
