Chapter 25 & 26 Homework
Which of the galaxies would have the least amount of ongoing star formation?
A/ elliptical
Why is a type Ia supernova considered a standard bulb?
All type Ia supernovae have roughly the same luminosity.
How is a galaxy's apparent recessional velocity computed?
From the redshift of the galaxy's spectrum
What is Hubble's law?
The more distant a galaxy is from us, the higher its apparent recessional velocity.
Spiral galaxies have more gas, dust, and younger stars than elliptical galaxies do.
True
Why does the rotation curve of the Milky Way look flat instead of like the solar system?
the presence of dark matter throughout the galaxy
How big is the visible disk of our Milky Way galaxy, its diameter from edge to edge?
100,000 light years
The Hubble Constant is . Estimate the distance to a galaxy with an apparent recessional velocity of 395 km/s. Express your answer in mega-light-years and round to the nearest 1 decimal place.
18.0
Which of the galaxies above would appear reddest in color?
A/ elliptical
Which of the following statements is true about stars in the Galactic disk and halo?
Disk stars have a higher abundance of elements heavier than helium because disk stars are, on average, younger.
Which of the above types of galaxy do you commonly find in the center of rich clusters?
Elliptical
Where in the Galaxy is our Solar System?
In a minor spiral arm
Which of the following statements are true about Sagittarius A*? Choose all that apply.
It was discovered as a source of radio waves. It is at the center of the Milky Way. It is orbited by a swarm of stars. It appears to be a supermassive black hole
What type of galaxy is pictured here?
an elliptical galaxy
What type of galaxy is pictured here?
an irregular galaxy
What can we imply from Hubble's Law?
the universe is expanding
What is dark matter?
An invisible source of gravity.
Match each component of the Milky Way with its description.
Contains the central bar- Bulge Contains the spiral arms- Disk Contains the globular clusters- Halo
Match the galaxy description to the galaxy type.
Regular shape, fuzzy, red.-Elliptical galaxy Regular shape, disk component, yellow bulge, blue disk.- Spiral galaxy Blue in color, no regular shape-Irregular galaxy
Which technique could allow you to estimate the distance to a galaxy that is 8 billion light-years away?
Using a type Ia supernova as a standard bulb
Which of the following best describes the current state of scientific knowledge of the composition of dark matter?
We aren't certain what dark matter is, but several hypotheses have been disproven, so we have a fair idea of what dark matter isn't.
Why are Cepheid variables important? Choose all that apply.
We can compute their luminosity from their period of pulsation. They help us to know the distances to nearby galaxies.
What type of galaxy is pictured here?
a spiral galaxy
Which type of galaxy is likely to contain both O-spectral type stars as well as M-spectral type stars?
spiral
