Quiz 4 Flashcards
How did Edwin Hubble prove that spiral nebulae were actually galaxies external to the Milky Way?
observing types of stars that had change in their brightness called cepheids. Started observing some of the stars in fuzzy nebulae and realized that they were different because the objects were too far away and light takes time to get here.
What are the main types of galaxies?
Ellipticals, Spirals, and Irregulars
Spirals can be ____ or not. The Milky Way has a _____ bar.
Barred. Small.
Elliptical Galaxies have ____ stars and almost no ____ and no _____
Elliptical Galaxies have old stars and almost no gas and no young stars and no spirals.
Describe what will happen between our galaxy and the Andromeda galaxy 5 billion years from now.
Collision, they will collide
Do stars collide during galaxies collisions? Why? Are new stars born? Why?
Stars do not collide, they are too far apart. New stars are born, because gas clouds collide and those collisions form stars.
Hubble found that v=HD. What is v and D and what does this equation tell us? How is H called?
v=hd. V stands for velocity. D stands for distance. H stands for hubble constant. This equation tells us further away= faster. Equation tells us expansion of the universe?
Galaxies can be found in _____
clusters together with thousands of other galaxies
Explain gravitational lens
When light from a distant galaxy passes next to a massive object it gets distorted and magnified.
What do galaxies have in their core
SMBH, can be billions of times more massive than the sun.
What are Quasars
super massive black holes that are only detected through radio telescopes
When AGN are also radio sources, what are they called?
Quasars
What do Hubble space telescope images of Quasars show
the host galaxy. Many of them are colliding galaxies.
_____ are distant objects that look like stars but are ______
Quasi Stellar objects, galaxies with SMBHs
What is the difference between an E0 and E7 galaxy
E0 Galaxy is very round
E7 galaxies are flat
What is a merger? And what may happen during the merging process? What will be the final product of a merger ?
when two (or more) galaxies collide. The collision rips streamers of stars from the galaxies, fuels an explosion of star birth, and results in both galaxies merging into one. Note: Stars do not collide when galaxies merge, due to the great distances between stars
How do we know there is dark matter in the universe? Do we know what dark matter is made of?
When astronomers look at a galaxy they can measure how fast stars are moving. When they add up all the matter in the stats and gas visible, it doesn’t add up correctly to what they see. We can see the bright matter like stars but we know some other matter is there because of how it pulls on the bright matter. It is made up of black holes and objects that are too small to be stars, and new particles smaller than atoms
When SMBH are active what happens
they have a jet, produce high energy and are called Active Galactic Nuclei or AGN
How do we know the Milky Way has a relatively small massive black hole
High resolution radio maps tracking the motion of stars at the center of the galaxy, by looking at the behavior of orbit of the stars. They had to look at the stars for several years and measure their speed to determine the size of the black hole. We think ours is a growing black hole
What is the most important image ever taken?
The Hubble Deep field
