Astronomy final exam #3

What is the diameter of the disk of the Milky Way?

100,000 light-years

What is a lenticular galaxy?

A galaxy with a central bulge and a disk like a spiral galaxy, but with no spiral arms.

Hubble's law was discovered using measurements of two properties of a galaxy: _________ and ____________

Distance; Recession velocity

T or F: Galaxies in the very early universe look a lot like galaxies in the local universe.

False

T or F: Most galaxies are isolated and do not interact gravitationally with other galaxies.

False

Hubble's law and the Big Bang theory are related because

Hubble's law is an observation that led to the development of the theory.

Which of the following best summarizes what we mean by dark energy?

It is a name given to whatever is causing the expansion of the universe to accelerate with time.

Why is the Milky Way Galaxy not expanding together with the rest of the universe?

Local gravity dominates over the expansion of the universe.

T or F: As the universe expands, its temperature decreases.

True

T or F: Population I stars are found in the halo.

True

T or F: The universe is continuing to cool today.

True

About two thirds of the nearby spiral galaxies don't have a round central bulge, but instead show

a central bulge with a bar of stars in the middle

When they look into the universe, astronomers observe that nearly gall galaxies are moving away from the Milky Way. This observation suggests that

an observer in a distant galaxy would make the same observation.

The vast majority of antimatter in the early universe:

annihilated with matter.

By examining rich clusters of galaxies, such as the Coma Clusters, astronomers have discovered that spiral galaxies

are found mostly in the outer regions of such clusters, not in the middle

The idea of the uniformity of the universe, also known as the ________________, is that the part of the universe we see around us is representative of the whole.

cosmological principle

Astronomers can get a rough estimate of the age of the universe from Hubble's law by

finding the inverse of the slope.

A starburst galaxy is a galaxy which

has a very high rate of star formation.

The orbits of stars in elliptical galaxies

have random orientations.

The youngest stars in the Milky Way are

in the disk.

The helium abundance in the current universe

is due partly to the Big Bang and partly to stellar evolution.

According to the Cosmological Principle, the universe

is isotropic and homogeneous

In clusters of galaxies, the most massive and most luminous galaxies are usually found

near the center of the cluster.

Put the following types of objects in order, starting with the first one to form after the Big Bang and ending with the last one to form.

protons, nuclei, neutral atoms

Galaxies in the young universe were _____________ galaxies in the universe today.

smaller and more irregular than

The cosmic microwave background (CMB) and the Big Bang are related because

the Big Bang theory predicted the existence of the CMB.

A team of astronomers manage to collect enough light from a galaxy far, far away to produce a spectrum. That spectrum has lines from the elements carbon, silicon, and sulfur. This tells the team that

the galaxy must have had an entire generation of stars that was born, lived, and died

An astronomer discovers a massive galaxy which has four nuclei. What is a likely explanation for a galaxy having more than one nucleus?

the galaxy must have swallowed several smaller galaxies that were its neighbors

In which of the following domains of the universe have astronomers NOT found evidence for the presence of dark matter today?

the solar system

By comparing the distances and velocities of galaxies moving away from us, Hubble and Humason showed that:

the velocity of recession of galaxies is proportional to their distance.

When astronomers say that the groups of galaxies are distributed isotropically, they mean that

the way galaxies are arranged in space looks the same in all directions

Which property is detectable for both dark matter and the supermassive black hole at the center of the Milky Way?

their gravity

Edwin Hubble developed a classification scheme for galaxies. By what characteristic did he classify galaxies?

their shape

One important way astronomers can learn in some detail about what happens when galaxies collide is

to simulate galaxy collisions on a large computer and watch what the simulation predicts