Astro 20 final

Pulsars cannot be black holes because

you will not see the pulsating light

The material that accretes onto a neutron star or black hole is expected to emit X-rays because

none of the above

A pulsar requires that a neutron star I.rotate rapidly. II.have a radius of at least 10 km. III.have a strong magnetic field. IV.rotate on an axis that is different from the axis of the magnetic field.

I, III & IV

How do Astronomers measure the period of pulsers?

They collect radiation emitted by the pulsar and measure the period with various detectors

The singularity of a black hole

None of the above

The initial stars to form in the Milky Way

had orbits that were very elliptical.

Globular clusters are primarily composed of

Old stars

The center of our galaxy most likley contains

a black hole

The orbits of population I stars I.are confined to disk of the galaxy. II.are very elliptical. III.are nearly circular. IV.are randomly inclined to the disk of the galaxy.

I & III

The traditional "top-down" theory states that the galaxies formed

none of the above

What value of absolute magnitude below correlate to the brightest stars?

-6

How are globular clusters formed?

None of the above

The central areas of our Milky Way cannot be observed in the visible part of the spectrum because

Astronomers have to look through a lot of gas and dust.

The blue color in Uranus and Neptune is caused

None of above

What is common between all Jovian planets (Jupiter like planets).

Have complicated atmospheres and an abundance of gases

What unit of measurement is typically used to determine distances in our Solar System

Astronomical Unit

The red shift of a galaxy can be used to measure the galaxy's

Speed as it moves away from us

The Milky Way is part of I.a poor cluster. II.a rich cluster. III.the Virgo Cluster. IV.the Local Group.

I and IV

Why do some galaxies collide?.

A combination of the the galaxies motion and a gravitational force

The look-back time is

a and b

Astronomers now think that a galaxy's shape depends on all of the following except

All of these may be important in determining a galaxy's shape.

The most common galaxies in the universe are

None of the above

The closest galaxy to our solar system is.

Small Magellanic Cloud

Observations of galaxies and clusters of galaxies indicate that about ____ percent of the matter in the universe is dark matter.

None of the above

Which of the following is correct about the Earth's Moon

It has little to no atmosphere

Supermassive black holes are believed to be located at the center of many galaxies because

the orbital motion of material near the center is very fast and indicates a very massive core.

What instrument (shown below) is used to measure the red shift?

Spectroscope

What analytical tool is available to measure distances to close by galaxies in the local group.

A graph relating the period of certain variable stars to luminosity

What method is used to determine the distances to the most distant galaxies?

Supernova observations

Why is Hubble's law so important?

Both a and b

The Milky Way Galaxy is a

Spiral

Which of the planets below do not have Moons

Mercury

All ____ galaxies are spiral galaxies that have small luminous nuclei.

Seyfert

The radio lobes that are on each side of some radio galaxies and jets from them produce mainly

synchrotron radiation.

Centaurus A is a radio galaxy that has a visible galaxy at the center. This central elliptical galaxy of Centaurus A is encircled by a ring of gas and dust, different from most elliptical galaxies. The dust ring orbits about an axis that is perpendicular to the axis of rotation of the elliptical galaxy. What does this suggest about this central elliptical galaxy of Centaurus A?

Centaurus A is probably the result of a merger of an elliptical galaxy and a spiral galaxy.

Which one of the statement is true about Quasars?

emitting a very large amount of energy per second.

Soon after discovery, it was observed that quasars had a starlike appearance which was blurred by Earth's atmospheric "seeing." Despite the blurring, it was realized that the intense energy emitting regions of quasars must be small because they

fluctuate rapidly on time scales as short as a few hours.

Evidence that supports quasars being the nuclei of very distant galaxies includes Gamma rays

none of the above

According to the unified model of active galactic nuclei, ____ is in the center surrounded by _________with a Type 1 Seyfert or Type 2 Seyfert being seen depending on the viewing angle.

a supermassive black hole; an accretion disk

What statement below best describes the planet Jupiter

In our solar system it is a large gaseous planet

In the unified model of active galactic nuclei, the broad line region in an active galactic nucleus is

None of the above

The hydrogen Balmer line can be used to measure

the red shift in a quasar

How are astronomers able to determine that quasars are so small?

They are variable over a short period of time.

What statement is true about super massive black holes?

none of the above

Space-time will be flat if

the average density of the universe is equal to the critical density.

In the late 1990s, it was announced that the expansion of the universe is accelerating. What does this imply from the perspective of the big bang?

A force exists that we knew nothing about that causes the acceleration.

The universe is about

14 billion years old.

An open universe means that the universe will

expand forever

After the first solid grains formed in our solar system, these particles could then grow by the process of ____, the collision and sticking of one particle with another to continue the formation of planetesimals. Each of these has many atoms or molecules.

accretion

Protoplanets

grew in size by the collision and coalescing of planetesimals.

A newly formed planet or large asteroid becomes molten due to ______.

Both of the above

Asteroids mostly populate the region between

Mars and Jupiter

The age of the solar system is believed to be approximately 4.6 billions years based on the data from

all of the above

The large planetesimals would have grown faster than the smaller planetesimals because

their stronger gravity would pull in more material.

Which of the following is the earliest starting point for the formation of our Sun and planets?

Gas cloud

Part of the current atmosphere of Earth is believed to be

composed of gases that were outgassed from the heated rocks sometime after the planet formed.

The uncompressed density of a planet in our solar system

is greatest for the planets closest to the sun.

How is the presence of space debris accounted for by solar system models?

a and b

The Earth most likely formed

the same time as the Sun

Why is the ozone layer important to life on Earth?

It blocks ultra violet radiation

How did astronomers generate an image of Venus?

Radar located on an orbiting satellite

Which of the solar system objects has very little to no atmosphere?

Mercury

Excess heating (known as the Greenhouse effect) in planetary atmospheres is caused by

Not allowing infrared light to emit off the planet

What would happen if the Earth and Mars had no tilt in their axis with respect to the Sun?

There would be no seasons

Which planet has been visited by the most space probes (as of today)?

Mars

Which of the following are classifications given to galaxies by Hubble

both a and b