Astronomy Test 3 Flashcards
When would the star reach the point of blowing themselves apart?
When a star’s mass (150 times our sun) is too great it generates so much power that it blows itself up.
What does it mean when a star is more luminous than another?
When a star is more luminous it means that it is either more massive and/or hotter in temperature.
What are brown dwarfs?
Smaller “failed stars” that can be found in the lower right hand corner of the HR diagram
When would a star fall of the main sequence?
A star falls off the main sequence when hydrogen fuses in the core of the star
What happens after hydrogen has completely stopped fusion in the core?
After hydrogen fusion has stopped the star will begin to heat up and expand
What is a product of helium fusion?
Carbon is a product of helium fusion
How does a red giant change near the end of its life?
A red star will become cooler and brighter as it evolves
What do we call the expanding shell of gas that is the remnant of a low-mass star?
The expanding shell of gas left from a low-mass star is called a planetary nebula
What is the last element found at a star’s core that cannot release energy either through fusion or fission?
Iron is the last element found at a star’s core when going through fusion
What can be found at the core of a planetary nebula?
White dwarves are found at the core of planetary nebula
What are the stages of a high mass and low mass star?
The stages of life for a star are:
Protostar, main-sequence, white dwarf, red giant >(high mass) supernova, neutron star or black hole
What causes a black hole?
Black holes from when the gravity of a massive star overcomes neutron degeneracy pressure and the core collapses
What is a possible result of a white dwarf gaining mass due to the accretion in a binary system?
The white dwarf will reach the limit it can of mass and collapse, leading to a supernova
What are some key things to know about novae?
-A star system that undergoes a nova may have another nova in the future
-A nova involves fusion taking place on the surface of a white dwarf
-When a star system undergoes a nova, it brightens considerably, but not as much as a star system undergoing a supernova
-The word nova means “new star” and originally referred to stars that suddenly appeared in the sky, then disappeared again after a few weeks
Where does hydrogen burn after the star has become a red giant?
Hydrogen will burn in only shells outside the core of a star after it becomes a red giant
What size is comparable to a white dwarf?
A white dwarf is comparable in size to the Earth
What is a pulsar and how does it appear?
A pulsar is a rapidly rotating neutron star that emits flashes of light several times per second with perfect regularity
When light appears red shifted what can we assume?
When light is red shifted we can assume that the light is coming from a compact, massive object (heavy gravity)
What is important to know about black holes?
-A black hole is any object from which the escape velocity equals the speed of light.
-Nothing is able to escape from inside the event horizon of a black hole
-If someone was to fall into a black hole you will never see them cross the event horizon, but they will appear more and more red shifted
-If we watch a clock fall towards a black hole, we will see it tick slower and slower
-If you fell into a black hole, you would experience time to be running normally as you plunged rapidly across the event horizon
-The singularity of a black hole is the center of the black hole
True or false: after several billion years a white dwarf is what will be left of our solar system?
True. After several billion years we would see a white dwarf as what is left of our solar system
How big is our milky way? (the disk)
The milky way is 100,000 light years in diameter
Where would we find globular clusters?
Globular clusters can be found in the halo of our galaxy
What can be found in the disk of our galaxy?
Some things that can be found in the disk are: open clusters, gas and dust, O and B stars, old K and M stars
What is the interstellar medium?
Interstellar medium is the space in between star systems and is made of mostly gas and dust
Where are elements past hydrogen and helium made?
Elements past hydrogen and helium would be found in stars or super novea where fusion is taking place
What proof do we have of dark matter?
We know there is dark matter in the galaxy because of stars orbital speeds away from the galactic center are showing a gravitational pull
How long does it take the sun to orbit the milky way galaxy?
It takes 230 million years for the sun to orbit the milky way galaxy
Do halo stars have rocky planets around them?
No, halo stars do not have rocky planets around them because there is not enough heavy elements is the area to form them
In what zodiac constellation is our galactic center (black hole) found?
Our galactic center can be found in the constellation Sagittarius
What is special about the spiral arms in the milky way galaxy?
In the spiral arms of the galaxy star formation is happening
True or false: Our galaxy is the most common type of galaxy for larger galaxies?
True: most large galaxies are spiral galaxies they are also most commonly found in large clusters
How do we know there’s a black hole at the center of our galaxy?
We know there’s a black hole at the center because of the motion of stars indicating a million solar masses within a small region (1 parsec across)
What is special about elliptical galaxies?
Elliptical galaxies appear reddest in color
What does hubble’s law teach us?
Hubble’s law teaches us that the more distant a galaxy is from us, the faster it moves away from us
How did Hubble discover the expansion of the universe?
He plotted velocity and distance against each other
Fill in the blank: the faster a spiral galaxy’s rotation speed, the more ______ it is
The faster a spiral galaxy’s rotation speed, the more luminous it is according to the tully-fisher relation
Why is stellar parallax so important?
Stellar parallax is the most accurate way to determine the distance to a nearby star
In order here is the best way to determine distance (nearest to furthest)
Parallax, main-sequence fitting, cepheid variables, white-dwarf supernovae, hubble’s law
Can we see past the cosmological horizon?
No, we cannot see past the cosmological horizon because that would mean we are looking past when the universe formed
When something is further away is it more red-shifted or blue-shifted?
The further something is the more red-shifted it becomes
What three elements are skipped during the triple alpha process?
Lithium, beryllium, and boron are usually skipped in the conversion of helium into carbon through the triple alpha process
