Astronomy Chapter 25 – Flashcards
Unlock all answers in this set
Unlock answersquestion
In a galaxy collision, two similar-sized galaxies pass through each other with a combined relative velocity of 1700 km/s .If each galaxy is 100 kpc across, how long does the event last?
answer
3.6x10^15 s
question
The Andromeda Galaxy is approaching our Galaxy with a radial velocity of 120 km/s.Given the galaxies' present separation of 800 kpc, and neglecting both the transverse component of the velocity and the effect of gravity in accelerating the motion, estimate when the two galaxies will collide.
answer
2.07x10^17s
question
Two galaxies are orbiting each other at a distance of 440 kpc . Their orbital period is estimated to be 33 billion years.Use Kepler's law (as stated in Section 23.6 in the textbook) to find the total mass of the pair
answer
6.86x10^11 solar masses
question
How massive are the largest known galaxies?
answer
a trillion solar masses
question
Based on galactic rotation curves and cluster dynamics, we think dark matter
answer
comprises over 90% of the entire mass of the universe.
question
Collisions between galaxies is thought to
answer
be commonplace.
question
The distance between adjacent galaxies in a typical cluster is about ________ times the size of a typical galaxy.
answer
five or less
question
Due to the galaxy density and collisions, ________ are rare in the centers of clusters.
answer
spirals
question
Collisions between galaxies
answer
cause the gas and dust clouds to collide, leading to rapid star formation.
question
According to the HST data, very distant (and early) galaxies tend to be
answer
smaller, bluer, and more irregular than modern ones.
question
A merger between two large galaxies of comparable size will most likely produce
answer
a large elliptical galaxy.
question
A merger between a small elliptical galaxy and a large spiral galaxy will most likely result in
answer
a large spiral.
question
The further away a galaxy is
answer
the longer ago it existed.
question
The energy radiated from a typical quasar requires that its black hole accrete about:
answer
10 solar masses per year.
question
A galaxy is at a distance of one billion light years. Which of the following is true?
answer
We see the galaxy the way it was one billion years ago.
question
A supernova occurred 10,000 years from now in a galaxy 50,000 light years away will be observed on Earth
answer
40,000 years from now.
question
What is the Great Wall?
answer
It is a large sheet of galaxies measuring 70 Mpc by 200 Mpc.
question
Rotation curves for spiral galaxies show
answer
most have dark halos.
question
As we look at larger and larger scales in the universe, we find
answer
a larger and larger percentage of the matter is dark.
question
When spiral galaxies do collide, the impact is greatest on their:
answer
giant molecular clouds.
question
Astronomers believe that a spiral galaxy may form
answer
from a collision between a small and large galaxy.
question
________ galaxies may bridge the gap between spiral galaxies and quasars.
answer
Seyfert
question
Active galaxies are having their central engines temporarily fed by what occurrence?
answer
a close interaction with a neighboring galaxy
question
If the merger theory is correct, the brightest active galactic nuclei should
answer
contain supermassive black holes.
question
A supernova that occurred 30,000 years ago in a galaxy 100,000 light years away will be observed on Earth
answer
70,000 years from now.
